RESUMEN
Flocalin (FLO) is a new ATP-sensitive K(+) (KATP) channel opener (KCO) derived from pinacidil (PIN) by adding fluorine group to the drug's structure. FLO acts as a potent cardioprotector against ischemia-reperfusion damage in isolated heart and whole animal models primarily via activating cardiac-specific Kir6.2/SUR2A KATP channels. Given that FLO also confers relaxation on several types of smooth muscles and can partially inhibit L-type Ca(2+) channels, in this study, we asked what is the mechanism of FLO action in bladder detrusor smooth muscle (DSM). The actions of FLO and PIN on contractility of rat and guinea pig DSM strips and membrane currents of isolated DSM cells were compared by tensiometry and patch clamp. Kir6 and SUR subunit expression in rat DSM was assayed by reverse transcription PCR (RT-PCR). In contrast to PIN (10 µM), FLO (10 µM) did not produce glibenclamide-sensitive DSM strips' relaxation and inhibition of spontaneous and electrically evoked contractions. However, FLO, but not PIN, inhibited contractions evoked by high K(+) depolarization. FLO (40 µM) did not change the level of isolated DSM cell's background K(+) current, but suppressed by 20 % L-type Ca(2+) current. Determining various Kir6 and SUR messenger RNA (mRNA) expressions in rat DSM by RT-PCR indicated that dominant KATP channel in rat DSM is of vascular type involving association of Kir6.1 and SUR2B subunits. Myorelaxant effects of FLO in bladder DSM are explained by partial blockade of L-type Ca(2+) channel-mediated Ca(2+) influx rather than by hyperpolarization associated with increased K(+) permeability. Thus, insertion of fluorine group in PIN's structure made the drug more discriminative between Kir6.2/SUR2A cardiac- and Kir6.1/SUR2B vascular-type KATP channels and rendered it partial L-type Ca(2+) channel-blocking potency.
Asunto(s)
Bloqueadores de los Canales de Calcio/farmacología , Canales de Calcio Tipo L/efectos de los fármacos , Canales KATP/agonistas , Relajación Muscular/efectos de los fármacos , Músculo Liso/efectos de los fármacos , Pinacidilo/análogos & derivados , Vejiga Urinaria/efectos de los fármacos , Animales , Bloqueadores de los Canales de Calcio/química , Canales de Calcio Tipo L/metabolismo , Estimulación Eléctrica , Cobayas , Técnicas In Vitro , Canales KATP/genética , Canales KATP/metabolismo , Masculino , Potenciales de la Membrana , Estructura Molecular , Músculo Liso/metabolismo , Pinacidilo/química , Pinacidilo/farmacología , Ratas Wistar , Transducción de Señal/efectos de los fármacos , Relación Estructura-Actividad , Receptores de Sulfonilureas/agonistas , Receptores de Sulfonilureas/metabolismo , Vejiga Urinaria/metabolismoRESUMEN
In the experiments on non-linear white rats with the model of acute hypoxia we have studied the changes of the functional state of kidneys after a single intraventricular administration of the original fluorine-containing KATP-sensitive potassium channels activator flocalin at the dose of 5 mg/kg on the background of induced water load. It has been shown that under the influence of prohypoxic factors: sodium nitrite (50 mg/kg, subcutaneously) and dinitrophenol (3 mg/kg, intraperitoneal) flocalin activates volume-regulating, ion-regulating and excretory functions of kidneys. Renal effects after activation of KATP-sensitive potassium channels in the rats with histohemic hypoxia were induced by the changes of tubular and predominantly glomerular processes. The increase of glomerular filtration rate, restoration of volatile distal reabsorption of potassium channels, decrease of sodium loss with urine, decrease ofproteinuria after a single administration of flocalin under conditions of acute hypoxia complement the range of protective effects of KATP-sensitive potassium channels activator flocalin.
Asunto(s)
Hipoxia/fisiopatología , Canales KATP/agonistas , Riñón/efectos de los fármacos , Pinacidilo/análogos & derivados , Sustancias Protectoras/uso terapéutico , Enfermedad Aguda , Animales , Modelos Animales de Enfermedad , Hipoxia/tratamiento farmacológico , Hipoxia/metabolismo , Activación del Canal Iónico/efectos de los fármacos , Riñón/metabolismo , Riñón/fisiopatología , Pruebas de Función Renal , Pinacidilo/administración & dosificación , Pinacidilo/farmacología , Pinacidilo/uso terapéutico , Sustancias Protectoras/administración & dosificación , Sustancias Protectoras/farmacología , Ratas , Sodio/orinaRESUMEN
The experiments in white laboratory rats have shown that a single intragasrtric administration of the new fluorine-containing potassium channel opener flocalin in a dose of 5 mg/kg in the initial stage of sublimate nephropathy increased the glomerular filtration rate, reduced creatininemia, increased urinary creatinine excretion, and decreased proteinuria. Under similar conditions, the administration of the calcium channel blocker diltiazem in a dose of 5 mg/kg (intragasrtric) showed a less pronounced antiproteinuric effect as compared to that of flocalin. A comparative assessment of the influence of flocalin and diltiazem on the basic renal function markers demonstrated predominant nephroprotective effect of flocalin in the treatment of acute toxic nephropathy.
Asunto(s)
Bloqueadores de los Canales de Calcio/farmacología , Diltiazem/farmacología , Riñón , Pinacidilo/análogos & derivados , Bloqueadores de los Canales de Potasio/farmacología , Proteinuria , Animales , Tasa de Filtración Glomerular/efectos de los fármacos , Riñón/lesiones , Riñón/patología , Riñón/fisiopatología , Pinacidilo/farmacología , Proteinuria/tratamiento farmacológico , Proteinuria/patología , Proteinuria/fisiopatología , RatasRESUMEN
In experiments on the anaesthetized dogs with modeling of experimental ischemia (90 min) and reperfusion (180 min) of myocardium it was investigated changes of biochemical processes in arterial blood at intragastric introduction of medicinal form (tablets) of flocalin (the fluorine-containing opener of ATP-sensitive potassium channels) in a dose 2,2 mg/kg. The data analysis allowed to define a few possible mechanisms of cardioprotective action offlocalin, which prevented the opening of a mitochondrial permeability transition pore (MPTP) and inhibition of apoptosis induced by it. They consist, from one side, in activating of the constitutive de novo biosynthesis of nitric oxide by cNOS, from other side, in suppression of inducible nitric oxide de novo synthesis by iNOS in such way to prevent the formation of toxic peroxynitrite by co-operation of surplus nitric oxide with superoxide anion, thereby limits the generation of toxic active forms of nitrogen (*NO2) and oxygen (*OH). The first effect of flocalin takes place due to limitation the degradation of L-arginine by arginase which keeps substrat for cNOS, second--due to the inhibition of superoxide generation, in particular, by xanthine oxidase (marker uric acid), lipoxigenase (marker LTC4) and cyclooxygenase (marker TxB2). Because LTC4 have coronaroconstrictory, arrhythmogenic and chemoattractory properties in the conditions of myocardial ischemia, inhibition of its production both with superoxide generation (markers H2O2 and diene conjugates) may be the another mechanisms of flocalin's cardioprotection. Powerful antiischemic action of flocalin (marker nitrite anion) as the mechanisms of cardioprotection is possible as well as inhibition of ATP and GTP degradation (marker hypoxanthine+xanthine+inosine levels in the blood) and, possibly, stimulation ofhaem degradation by haem oxygenase (markers total bilirubin and Fe in the blood). Diminishing content of free arachidonic acid in arterial blood can testify inhibition of cellular membranes phospholipides degradation by phospholipase A2 as a result of flocalin cardioprotection.
Asunto(s)
Cardiotónicos/farmacología , Corazón/efectos de los fármacos , Mitocondrias/efectos de los fármacos , Proteínas de Transporte de Membrana Mitocondrial/antagonistas & inhibidores , Daño por Reperfusión Miocárdica/prevención & control , Pinacidilo/análogos & derivados , Animales , Apoptosis/efectos de los fármacos , Arginasa/antagonistas & inhibidores , Arginasa/metabolismo , Perros , Corazón/fisiopatología , Hemo Oxigenasa (Desciclizante)/antagonistas & inhibidores , Hemo Oxigenasa (Desciclizante)/metabolismo , Radical Hidroxilo/antagonistas & inhibidores , Lipooxigenasa/metabolismo , Mitocondrias/metabolismo , Proteínas de Transporte de Membrana Mitocondrial/metabolismo , Poro de Transición de la Permeabilidad Mitocondrial , Daño por Reperfusión Miocárdica/metabolismo , Daño por Reperfusión Miocárdica/fisiopatología , Óxido Nítrico/metabolismo , Óxido Nítrico Sintasa de Tipo I/metabolismo , Óxido Nítrico Sintasa de Tipo II/antagonistas & inhibidores , Óxido Nítrico Sintasa de Tipo II/metabolismo , Ácido Peroxinitroso/antagonistas & inhibidores , Pinacidilo/farmacología , Comprimidos , Xantina Oxidasa/antagonistas & inhibidores , Xantina Oxidasa/metabolismoRESUMEN
The influence of the new cardioprotector flocalin was investigated on the culture of rat's neonatal cardiomyocytes during anoxia-reoxygenation modelling. The mechanisms of apoptosis and necrosis were investigated under influence of ATP-sensitive potassium (K(ATP)) channels activation and in conditions of blocking of the L-type calcium (VGCCs) channels. Flocalin was added in the culture medium in the dose 5 and 20 microM at 2 minutes before anoxia (30 minutes) and following reoxygenation (60 minutes). These doses are near to: the first dose means the opening of K(ATP) channels and the second one means the IC50 block of VGCCs. It is discovered that in dose 5 microM of flocalin drew the change of correlation of living, necrotizing and apoptizing cells drew side-shifting living. The number of live cells was almost the same like in control (experiments without anoxia-reoxygenation modelling). The opening of K(ATP) channels decreases necrosis in two times and fully prevented development of apoptosis which was induced anoxia-reoxygenation modelling. Flocalin depressed the apoptosis of neonatal cardiomyocytes so that he was on to 36% less than in control group (without anoxia-reoxygenation). But in the high dose (20 microM) that provokes not only K(ATP) channels opening but also IC50 block of VGCCs cardioprotection was not detected after modelling of anoxia-reoxygenation. The last can be investigation both enough strong activating of the potassium channels and by investigation of both factors are opening of potassium and inhibition of VGCCs channels and, accordingly, substantial diminishing of level of introcellular Ca2+ and violation of metabolic processes yet to anoxia-reoxygenation. Thus, small doses of flocalin, that induce moderate opening of K(ATP) channels significantly decrease the number of necrotic and apoptotic cells in culture of rat neonatal cardiomyocytes induced by anoxia-reoxygenation.
Asunto(s)
Canales de Calcio Tipo L/metabolismo , Cardiotónicos/farmacología , Canales KATP/metabolismo , Miocitos Cardíacos/efectos de los fármacos , Oxígeno/farmacología , Pinacidilo/análogos & derivados , Anaerobiosis , Animales , Animales Recién Nacidos , Apoptosis/efectos de los fármacos , Células Cultivadas , Activación del Canal Iónico/efectos de los fármacos , Canales KATP/agonistas , Canales KATP/antagonistas & inhibidores , Miocitos Cardíacos/citología , Miocitos Cardíacos/metabolismo , Necrosis/metabolismo , Pinacidilo/farmacología , RatasRESUMEN
In experiments on the anaesthetized dogs the influence of a new fluorine-containing opener of ATP-sensitive potassium (K(ATP)) channels flocalin on the cardiohemodynamic of great animals in vivo was studied. Flocalin introduced intravenously in doses 0.01 - 1.5 mgs/kg. It is shown that it reduces in dose-dependent manner a system arterial pressure, perfusion pressure in coronary artery and general peripheral resistance of vessels with maximal effects on 56.8 +/- 2.7, 22.4 +/- 4.7 and 47.2% +/- 6.5% accordingly at most dose 1.5 mgs/kg. Flocalin causes development of cardiodepressive reactions in heart, that is exhibited in dose-dependent the decrease of pressure in the left ventricle, speed of growth (dP/dt(max)) and reduction (dP/dt(min)) in it's of pressure with maximal effects on 37.1 +/- 5.1, 51.2 +/- 9.4 and 55.6% +/- 6.9% accordingly at introduction of most dose of flocalin. Diminish of the cardiac out put and heart rate with a maximal effects on 23.1% +/-12.7% and 19.2% +/- 1.7% accordingly at a dose 1.0 mgs/kg was shown. It should be noted that considerable reduction of heart rate and general peripheral resistance of vessels takes place only at the large doses of flocalin - 1 and 1.5 mgs/kg. Thus, it is shown that activation of K(ATP) channels by flocalin causes the dose-dependent decrease of pressure in the system of circulation of blood and contraction activity of myocardium.
Asunto(s)
Vasos Coronarios/efectos de los fármacos , Corazón/efectos de los fármacos , Canales KATP/agonistas , Pinacidilo/análogos & derivados , Animales , Presión Arterial/efectos de los fármacos , Vasos Coronarios/fisiología , Perros , Relación Dosis-Respuesta a Droga , Femenino , Corazón/fisiología , Frecuencia Cardíaca/efectos de los fármacos , Inyecciones Intravenosas , Activación del Canal Iónico/efectos de los fármacos , Activación del Canal Iónico/fisiología , Canales KATP/metabolismo , Masculino , Contracción Miocárdica/efectos de los fármacos , Pinacidilo/farmacología , Resistencia Vascular/efectos de los fármacos , Resistencia Vascular/fisiología , Función Ventricular Izquierda/efectos de los fármacos , Función Ventricular Izquierda/fisiologíaRESUMEN
In experiments in vitro on the mitochondria isolated from the rat's heart we studied the effects of the openers of ATP-sensitive potassium channels (K(ATP)-channels), flocalin and tioflocalin, on the calcium-induced mitochondrial pore (MPTP) opening. Flocalin and tioflocalin caused moderate Ca(2+)-independent mitochondria swelling, which was prevented by a specific inhibitor of 5-hydroxydecanoate. This allowed to identify these compounds as mitochondrial K(ATP)-channels openers. We found that concentration-dependent inhibitory effects (10(-7) to 10(-4) M) of flocalin (with IC50 = 50 microM) and tioflocalin (with IC50 = 2,7 microM) on Ca(2+)-induced mitochondrial swelling (MPTP opening) in the heart characterized more powerful cardioprotective action of the latter. It was shown that the administration of these compounds in experiments in vivo decreased the sensitivity of the MPTP opening to Ca2+. Thus, under physiological conditions the activators K(ATP)-channels probably provide the membrane-stabilizing effects, thereby effectively increasing the organelles resistance to Ca2+, an inductor of MPTP. The results obtained allowed to characterize the role of the compound studied as cardioprotectors and regulators of the MPTP formation in the heart, indicated their anti-ischemic and anti-apoptotic effects that can be used in order to correct the mitochondrial dysfunction under pathological conditions of the cardiovascular system.
Asunto(s)
Calcio/farmacología , Cardiotónicos/farmacología , Activación del Canal Iónico/efectos de los fármacos , Mitocondrias Cardíacas/efectos de los fármacos , Pinacidilo/análogos & derivados , Canales de Potasio/metabolismo , Animales , Cardiotónicos/química , Relación Dosis-Respuesta a Droga , Técnicas In Vitro , Mitocondrias Cardíacas/metabolismo , Dilatación Mitocondrial/efectos de los fármacos , Pinacidilo/química , Pinacidilo/farmacología , Ratas , Ratas WistarRESUMEN
Fluorine-containing pinacidil-derivative flocalin is an effective adenosine triphosphate-sensitive potassium (K(ATP))-channel opener with pronounced vasodilatory, cardioprotective effects and low general toxicity. By activating cardiac K(ATP) channels, flocalin hyperpolarizes cardiac myocytes, decreases their excitability, reduces Ca(2+) entry, and inhibits Ca(2+)-dependent signalling processes. Since our previous studies indicated that the drug also influences the rate of rise and amplitude of the cardiomyocyte's action potential, here we have investigated its possible actions on depolarizing inward currents through voltage-gated sodium (VGSC) and L-type calcium (VGCC) channels. Experiments were conducted on cultured cardiac myocytes prepared from the whole hearts of neonatal rats and maintained in culture for 1-3 days using whole-cell patch-clamp technique with no distinction of myocyte's type. Flocalin concentration dependently inhibited the Na(+) inward current through VGSCs with IC(50) = 17.4 µM and a maximal extent of 0.54, slowed down its inactivation kinetics, and hyperpolarized steady-state inactivation by 5.6 mV. The drug also inhibited calcium current through L-type VGCCs with IC(50) = 24.1 µM and a maximal block of 0.38, without affecting its inactivation but producing 5.3-mV hyperpolarization shifting of steady-state activation. Inhibition of both depolarizing currents by flocalin in addition to its ability to open K(ATP) channels enhances the suppressive action of the drug on cardiac excitability and broadens its pharmacological effects. Since, according to our previous data, cardiac K(ATP)-channel opening by flocalin occurs with ÐC(50) = 8 µM, the possibility of partial blockade of VGSC and L-type VGCCs should be considered when determining the therapeutic concentrations of the compound during its use as a cardioprotector.
Asunto(s)
Canales de Calcio Tipo L/efectos de los fármacos , Canales KATP/efectos de los fármacos , Pinacidilo/análogos & derivados , Canales de Sodio Activados por Voltaje/efectos de los fármacos , Animales , Animales Recién Nacidos , Canales de Calcio Tipo L/metabolismo , Cardiotónicos/administración & dosificación , Cardiotónicos/farmacología , Células Cultivadas , Relación Dosis-Respuesta a Droga , Concentración 50 Inhibidora , Canales KATP/metabolismo , Miocitos Cardíacos/efectos de los fármacos , Miocitos Cardíacos/metabolismo , Técnicas de Placa-Clamp , Pinacidilo/administración & dosificación , Pinacidilo/farmacología , Ratas , Canales de Sodio Activados por Voltaje/metabolismoRESUMEN
In experiments on the anaesthetized dogs with modeling of experimental ischemia (90 min) and reperfusion (180 min) it was investigated the changes of biochemical processes in the different areas of heart (intact, risk and necrotic zone) during intragastric introduction of medicinal form (tablets) of flocalin (the fluorine-containing opener of ATP-sensitive potassium channels) in a dose 2,2 mg/kg. The data analysis allowed to define a few possible cardioprotective mechanisms of flocalin action at ischemia-reperfusion conditions: the preservation of sufficient levels of de novo (by cNOS) NO synthesis, an inhibition of de novo (by iNOS) and salvage (by NADH-dependent nitratreductase) NO synthesis, an inhibition of L-arginine degradation by arginase, an inhibition of oxidizing metabolism due to limitation of ROS and RNS generation, inhibition of free arachidonic acid and eicosanoids synthesis, inhibition of ATP and GTP degradations and, possibly, stimulation of protective haem degradation. These changes may prevent formation of toxic peroxynitrite and suggest the possibility of participating in flocalin-mediated cardioprotective effects of warning a mitochondrial permeability transition pore (MPTP) opening and inhibition of apoptosis and/or necrosis of cardiomyocytes induced by it.
Asunto(s)
Canales KATP/agonistas , Mitocondrias Cardíacas/efectos de los fármacos , Miocardio/metabolismo , Óxido Nítrico/biosíntesis , Pinacidilo/análogos & derivados , Daño por Reperfusión/tratamiento farmacológico , Adenosina Trifosfato/metabolismo , Animales , Apoptosis/efectos de los fármacos , Ácido Araquidónico/antagonistas & inhibidores , Ácido Araquidónico/metabolismo , Arginasa/antagonistas & inhibidores , Arginasa/metabolismo , Arginina/metabolismo , Perros , Eicosanoides/antagonistas & inhibidores , Eicosanoides/metabolismo , Guanosina Trifosfato/metabolismo , Hemo , Canales KATP/metabolismo , Mitocondrias Cardíacas/metabolismo , Proteínas de Transporte de Membrana Mitocondrial/antagonistas & inhibidores , Proteínas de Transporte de Membrana Mitocondrial/metabolismo , Poro de Transición de la Permeabilidad Mitocondrial , Miocardio/patología , Nitrato-Reductasa (NADH)/metabolismo , Óxido Nítrico/agonistas , Óxido Nítrico Sintasa de Tipo I/metabolismo , Óxido Nítrico Sintasa de Tipo II/metabolismo , Pinacidilo/administración & dosificación , Pinacidilo/uso terapéutico , Especies de Nitrógeno Reactivo/metabolismo , Especies Reactivas de Oxígeno/metabolismo , Daño por Reperfusión/metabolismoRESUMEN
In experiments on anaesthetized dogs with modeling of experimental ischemia (90 min) and reperfusion (180 min), the cardioprotective influence of the pharmacological preconditioning caused by intragastric (with a help of catheter) introduction of medicinal form (tablets) of new fluorine-containing opener of ATP-sensitive potassium channels flocalin was shown. Flocalin was introduced in a dose 2.2 mg/kg, which in the conditions of physiological norm has a minimum influence on the parameters of cardiohemodynamic. The conducted research allowed to define the changes of these parameters during development of antiischemic protective effect of pharmacological preconditioning, caused by the medicinal form of flocalin, and describes basic cardioprotective mechanisms, related to the changes of cardiohemodynamic in the dynamics of ischemia-reperfusion of myocardium. In our opinion, to positive influences of flocalin, which are possibly related to cardioprotective action, it is possible to add the prevention of an increase of general peripheral resistance, resistance of coronal vessels of heart, and relative preservation of myocardium contractility in the period of reperfusion. Also these positive effects can be explained by moderate decrease of blood pressure that decreases the loading on the damaged heart and allows to preserve cardiac emission in the first period of ischemia. One of the major indexes of development of protective mechanism of pharmacological preconditioning caused by preischemic introduction of medicinal form of flocalin is the diminishing of infarct size of myocardium in experiments with ischemia-reperfusion of myocardium on 42.53% +/- 2.91% versus control experiments.
Asunto(s)
Cardiotónicos/uso terapéutico , Daño por Reperfusión Miocárdica/prevención & control , Pinacidilo/análogos & derivados , Animales , Cardiotónicos/administración & dosificación , Circulación Coronaria/efectos de los fármacos , Modelos Animales de Enfermedad , Perros , Hemodinámica/efectos de los fármacos , Precondicionamiento Isquémico Miocárdico/métodos , Canales KATP/agonistas , Contracción Miocárdica/efectos de los fármacos , Daño por Reperfusión Miocárdica/metabolismo , Daño por Reperfusión Miocárdica/patología , Daño por Reperfusión Miocárdica/fisiopatología , Necrosis , Pinacidilo/administración & dosificación , Pinacidilo/uso terapéuticoRESUMEN
BACKGROUND AND PURPOSE: A class of drugs known as K(ATP) -channel openers induce cardioprotection. This study examined the effects of the novel K(ATP) -channel opener, the fluorine-containing pinacidil derivative, flocalin, on cardiac-specific K(ATP) -channels, excitability of native cardiac myocytes and on the ischaemic heart. EXPERIMENTAL APPROACH: The action of flocalin was investigated on: (i) membrane currents through cardiac-specific K(ATP) -channels (I(KATP) ) formed by K(IR) 6.2/SUR2A heterologously expressed in HEK-293 cells (HEK-293(6.2/2A) ); (ii) excitability and intracellular Ca²(+) ([Ca²(+) ](i) ) transients of cultured rat neonatal cardiac myocytes; and (iii) functional and ultrastructural characteristics of isolated guinea-pig hearts subjected to ischaemia-reperfusion. KEY RESULTS: Flocalin concentration-dependently activated a glibenclamide-sensitive I(KATP) in HEK-293(6.2/2A) cells with an EC50= 8.1 ± 0.4 µM. In cardiac myocytes, flocalin (5 µM) hyperpolarized resting potential by 3-5 mV, markedly shortened action potential duration, reduced the amplitude of [Ca²(+) ](i) transients by 2-3-fold and suppressed contraction. The magnitude and extent of reversibility of these effects depended on the type of cardiac myocytes. In isolated hearts, perfusion with 5 µmol·L⻹ flocalin, before inducing ischaemia, facilitated restoration of contraction during reperfusion, decreased the number of extrasystoles, prevented the appearance of coronary vasoconstriction and reduced damage to the cardiac tissue at the ultrastructural level (state of myofibrils, membrane integrity, mitochondrial cristae structure). CONCLUSION AND IMPLICATIONS: Flocalin induced potent cardioprotection by activating cardiac-type K(ATP) -channels with all the benefits of the presence of fluorine group in the drug structure: higher lipophilicity, decreased toxicity, resistance to oxidation and thermal degradation, decreased metabolism in the organism and prolonged therapeutic action.
Asunto(s)
Cardiotónicos/farmacología , Canales KATP/metabolismo , Moduladores del Transporte de Membrana/farmacología , Miocitos Cardíacos/efectos de los fármacos , Pinacidilo/análogos & derivados , Daño por Reperfusión/tratamiento farmacológico , Sarcolema/efectos de los fármacos , Animales , Cardiotónicos/química , Células Cultivadas , Flúor/análisis , Gliburida/farmacología , Cobayas , Células HEK293 , Corazón/efectos de los fármacos , Corazón/fisiopatología , Humanos , Masculino , Potenciales de la Membrana/efectos de los fármacos , Moduladores del Transporte de Membrana/química , Moduladores del Transporte de Membrana/metabolismo , Miocardio/metabolismo , Miocitos Cardíacos/metabolismo , Técnicas de Placa-Clamp , Pinacidilo/química , Pinacidilo/farmacología , Ratas , Daño por Reperfusión/metabolismo , Sarcolema/metabolismoRESUMEN
In experiments on anesthetized dogs it was shown that the amplitude and duration of hypotensive effect of flocalin, a fluorine-containing pinacidil analogue, were dose-dependent and similar to those evoked by the known ATP-sensitive potassium channel opener pinacidil. However, flocalin appeared to be 3.5 times less toxic than pinacidil. Registration of systemic arterial pressure (SAP) has shown that following intravenous introduction of the threshold dose of flocalin (0.05 mg/ kg) the dilatation lasts around three minutes with the amplitude 9.52% +/- 2.01% (n=7, P < 0.05). Introduction of flocalin in a dose 0.5 mg/kg and above reduced SAP on more than 37%. Flocalin at 0.5, 0.75, 1.0 and 1.5 mg/kg reduced SAP by 42.07 +/- 6.18 (n=5, P < 0.05); 44.22 +/- 4.87 (n=3, P < 0.05); 44.3 +/- 4.59 (n=5, P < 0.05) and 66.28 +/- 3.15 mm Hg (n=3, P < 0.05), accordingly. Intravenous introduction of high doses of flocalin (0.75-1.5 mg/kgs) quite often reduced SAP to 40-50 mm Hg. However, such dangerous reduction in arterial pressure was comparatively short and lasted not more than 15 minutes, and then (usually within an hour) SAP gradually restored. Introduction of flocalin in hip artery, while measuring the perfusion pressure, produced practically similar results. In our opinion, the optimal cardioprotective doses of flocalin were 0.1 and 0.2 mg/kg. In experiments with acute ischemia and reperfusion of myocardium, preischemic introduction of flocalin at 0.1 and 0.2 mg/kg reduced an infarct size of myocardium by 37-40% and reduced SAP within first 5 and 25 minutes, accordingly.
Asunto(s)
Flúor/química , Activación del Canal Iónico/efectos de los fármacos , Canales KATP/agonistas , Pinacidilo/análogos & derivados , Vasodilatación/efectos de los fármacos , Vasodilatadores/farmacología , Animales , Presión Sanguínea/efectos de los fármacos , Perros , Relación Dosis-Respuesta a Droga , Femenino , Inyecciones Intraarteriales , Inyecciones Intravenosas , Masculino , Pinacidilo/administración & dosificación , Pinacidilo/efectos adversos , Pinacidilo/química , Pinacidilo/farmacología , Factores de Tiempo , Vasodilatadores/administración & dosificación , Vasodilatadores/efectos adversos , Vasodilatadores/químicaRESUMEN
In experiments on the anaesthetized dogs we investigated the influence of a new fluorine-containing opener of ATP-sensitive potassium channels of sarcolemal and mitochondrial membranes flocalin on the level of glucose in arterial blood at physiological conditions and under ischemia (90 min) and reperfusion (180 min) of myocardium. It was shown that intravenous introduction of flocalin in doses 0,1 - 1,0 mg/kg did not change the level of glucose in blood. In experiments with ischemia-reperfusion of myocardium, flocalin also did not increase the level of glucose during all experiment (5,5 hours) after intragastric (with a help of catheter) introduction of drug form (tablets) at cardiorotective dose of 2,2 mg/kg. However, intravenous introduction of flocalin in the dose of 1,5 mg/kg, which 15 times exceeded a cardioprotective dose of 0,1 mg/kg increased the glucose level 1,33 fold. It should be noted that this increase was not sustained and the level of glucose restored to the initial level within 1 hour. Identical changes of indexes of cardiohemodynamic and the level of glucose in arterial blood under introduction of identical doses of flocalin at the beginning and at the end of experiment (total dose of flocalin reached 4 - 4,5 mg/kg) can testify the absence of cumulative effect of flocalin at these experimental conditions. Thus, strong cardioprotective properties, hypotoxicity and the absence of meaningful changes in a carbohydrate exchange allow to consider a new fluorine-containing opener of K(ATP) channels of flocalin as perspective drug for clinical use.
Asunto(s)
Glucemia/metabolismo , Cardiotónicos/farmacología , Canales KATP/agonistas , Daño por Reperfusión Miocárdica/prevención & control , Pinacidilo/análogos & derivados , Administración Oral , Animales , Cardiotónicos/administración & dosificación , Cardiotónicos/efectos adversos , Cardiotónicos/uso terapéutico , Perros , Relación Dosis-Respuesta a Droga , Femenino , Inyecciones Intravenosas , Masculino , Daño por Reperfusión Miocárdica/sangre , Daño por Reperfusión Miocárdica/metabolismo , Pinacidilo/administración & dosificación , Pinacidilo/efectos adversos , Pinacidilo/farmacología , Pinacidilo/uso terapéutico , Factores de TiempoRESUMEN
In experiments on isolated Langendorff perfused hearts of guinea pig with modeling of ischemia (20 min) and reperfusion (40 min) the cardioprotective effects of drug form of new fluorine-containing K(ATP) channels opener flokalin were shown. Preliminary preischemic perfusion of isolated heart with new form of flokalin (5 M) for 5 minutes significantly improved the recovery of contractive function of ischemic myocardium at reperfusion. In particular, it considerably reduced time of ischemic heart contract recovery from the beginning of reperfusion. Recovery of systolic and developed pressure was improved and the increasing of end-diastolic pressure in left ventricle of heart was prevented. Vasodilatoric and antiarrhythmic properties of new drug form of flokalin can assist to it's cardioprotective effects. The vasoconstriction of coronary vessels was prevented and number of extrasystoles at reperfusion of ischemic heart was decreased.
Asunto(s)
Cardiotónicos/farmacología , Flúor/química , Corazón/efectos de los fármacos , Canales KATP/metabolismo , Daño por Reperfusión Miocárdica/prevención & control , Miocardio/metabolismo , Pinacidilo/análogos & derivados , Animales , Cardiotónicos/química , Cobayas , Pruebas de Función Cardíaca , Técnicas In Vitro , Masculino , Reperfusión Miocárdica , Daño por Reperfusión Miocárdica/metabolismo , Pinacidilo/química , Pinacidilo/farmacologíaRESUMEN
In experiments on the anaesthetized dogs with modeling of experimental ischemia (90 min) and reperfusion (180 min), the participation of biochemical processes in the cardioprotective effect of the preischemic activation of ATP-sensitive potassium (KATP) channels caused by intravenous introduction of flokalin, a new fluorine-containing opener of these channels was shown. Flokalin was introduced in a dose 0.1 mg/kg of animal body weight which practically did not change the parameters of hemodynamic in normoxia. Thus, the experiments investigating the influence offlokalin on changes of biochemical parameters of arterial blood during ischemia-reperfusion of myocardium showed certain features of ischemia-reperfusion syndrome development during stimulation of K(ATP) channels. The analysis of biochemical parameters of blood showed that flokalin suppressed free radical reactions and had antioxidant properties: reduced quantity of H2O2 and NO3- (the last can interpreted as a reduction in peroxynitrites formation), prevented the decline of catalase and superoxide dismutase activity. Practically constant content of low-molecular nitrosothiols in blood during all duration of experiment and increase of NO2-level during reperfusion may indicate on intact functions of the NO system and protective influence of flokalin during ischemia-reperfusion of myocardium. Practically unchanged content of inorganic phosphorus and uric acid in blood during ischemia- reperfusion under conditions of preischemic introduction of flokalin indicates the prevention of ATP degradation and fomation of both superoxide anion by xanthinoxidase and peroxynitrite by it interaction with nitric oxide. All mentioned properties of flokalin related to the changes of biochemical parameters of arterial blood, together with the changes of parameters of hemodynamics, result in diminishment of infarct size of myocardium after ischemia-reperfusion by 37% versus control experiments. K(ATP) channels, flokalin, ischemia-reperfusion, free radikaly, NO system.
Asunto(s)
Cardiotónicos/farmacología , Canales KATP/metabolismo , Daño por Reperfusión Miocárdica/sangre , Daño por Reperfusión Miocárdica/metabolismo , Pinacidilo/análogos & derivados , Animales , Antioxidantes/metabolismo , Cardiotónicos/administración & dosificación , Cardiotónicos/uso terapéutico , Modelos Animales de Enfermedad , Perros , Radicales Libres/sangre , Hemodinámica/efectos de los fármacos , Infarto del Miocardio/patología , Infarto del Miocardio/prevención & control , Daño por Reperfusión Miocárdica/patología , Daño por Reperfusión Miocárdica/fisiopatología , Fósforo/sangre , Pinacidilo/administración & dosificación , Pinacidilo/farmacología , Pinacidilo/uso terapéutico , Ácido Úrico/sangreRESUMEN
In experiments on anaesthetized dogs with modeling of experimental ischemia (90 min) and reperfusion (180 min) the cardioprotective influence of the preischemic activation of ATP-sensitive potassium (K(ATP)) channels by intravenous introduction of flokalin, a new fluorine-containing opener of these channels was shown. Flokalin was introduced in dose 0.1 mg/kg of animal body weight which practically did not change the parameters of hemodynamic in conditions of normoxia. Thus, the experiments performed about flokalin influence on changes of cardiohemodynamic during ischemia-reperfusion of myocardium showed certain features of ischemia-reperfusion syndrome development under conditions of K(ATP) channels activity stimulation. In our opinion, positive influence offlokalin can be explained by moderate decrease of blood pressure that decreases loading of the damaged heart and allows to preserve cardiac emission in the first period of ischemia. Also, these positive effects can be explained by prevention of the increase of coronal vessel resistance and relative preservation of myocardium contractility indexes by flokalin in the period of reperfusion. All protective properties of flokalin showed above result in diminishing of infarct size of myocardium after ischemia-reperfusion on 37% versus control experiments.
Asunto(s)
Cardiotónicos/uso terapéutico , Hemodinámica/efectos de los fármacos , Canales KATP/metabolismo , Daño por Reperfusión Miocárdica/prevención & control , Miocardio/patología , Pinacidilo/análogos & derivados , Animales , Presión Sanguínea/efectos de los fármacos , Gasto Cardíaco/efectos de los fármacos , Cardiotónicos/administración & dosificación , Modelos Animales de Enfermedad , Perros , Frecuencia Cardíaca/efectos de los fármacos , Contracción Miocárdica/efectos de los fármacos , Infarto del Miocardio/metabolismo , Infarto del Miocardio/patología , Infarto del Miocardio/fisiopatología , Infarto del Miocardio/prevención & control , Daño por Reperfusión Miocárdica/metabolismo , Daño por Reperfusión Miocárdica/patología , Daño por Reperfusión Miocárdica/fisiopatología , Miocardio/metabolismo , Necrosis , Pinacidilo/administración & dosificación , Pinacidilo/uso terapéuticoRESUMEN
In experiments on isolated Langendorff perfused hearts of guinea pig with modeling of ischemia (20 min) and reperfusion (40 min) the cardioprotective effects of flokalin were shown. Preliminary preischemic perfusion of isolated heart with flokalin (5 mM) for 5 minutes has significantly improved the recovery of contractive function ofischemic myocardium at repcrfusion. Particularly, recovery of systolic and developed pressure was improved and the increasing of end-diastolic pressure in left ventricle was prevented. The vasoconstriction of coronary vessels was prevented and number of extrasystols at reperfusion of ischemic heart was decreased. Morphological studies have shown that flokalin prevents the significant damage of myocardial structure and the development of hypercontraction of myofibrils at ischemia-reperfusion of myocardium. It also preserves the intact sarcolemma and intracellular organelles. The intact structure of mitochondria also was saved by flokalin that maintains the energy potential of myocardium. Using the selective blocker of mitochondrial K(ATP) channels 5-hydroxydecanoate (200 mM) allows to determine the relative role of sarcolemmal and mitochondrial K(ATP) channels activation in these effects. It was shown that mitochondrial as well as sarcolemmal K(ATP) channels play role in the recovery of ischemic myocardium functions: first are responsible for recovery of contractive function and second are responsible for coronary blood flow recovery.
Asunto(s)
Cardiotónicos/farmacología , Mitocondrias Cardíacas/metabolismo , Daño por Reperfusión Miocárdica/prevención & control , Pinacidilo/análogos & derivados , Canales de Potasio/metabolismo , Sarcolema/metabolismo , Animales , Ácidos Decanoicos/farmacología , Cobayas , Hidroxiácidos/farmacología , Técnicas In Vitro , Masculino , Mitocondrias Cardíacas/ultraestructura , Daño por Reperfusión Miocárdica/metabolismo , Daño por Reperfusión Miocárdica/patología , Pinacidilo/farmacología , Bloqueadores de los Canales de Potasio/farmacología , Sarcolema/ultraestructuraRESUMEN
The effects of four new fluorine-containing pinacidyl analogs (FPs) on the bladder contractile function in vitro and in vivo, and on the vessel tone in vitro were examined. All the four drugs produced a concentration-dependent relaxation of isolated rat detrusor strips and isolated aorta rings. The contractility inhibition effect of compound FP-5 was decreased by preliminary glibenclamide perfusion. This compound also effectively inhibited bladder contractility function in vivo.
Asunto(s)
Compuestos de Anilina/farmacología , Vasos Sanguíneos/efectos de los fármacos , Guanidinas/farmacología , Moduladores del Transporte de Membrana/farmacología , Contracción Muscular/efectos de los fármacos , Pinacidilo/análogos & derivados , Canales de Potasio/agonistas , Vejiga Urinaria/efectos de los fármacos , Compuestos de Anilina/química , Animales , Aorta/efectos de los fármacos , Femenino , Flúor/química , Guanidinas/química , Moduladores del Transporte de Membrana/química , Pinacidilo/química , Ratas , Ratas EndogámicasRESUMEN
The effects of the new fluorine-containing guanidine-derivate compounds on bladder contractile functionwere examined on isolated bladder strips in vitro. Female rats (250-350 g) were used. The bladder was removed and placed in the room temperaturePSS of the following composition (mM): NaCl (118.4), KCl (4.7),CaCl2 (2.5), MgSO4 (1.2), KH2PO4 (1.2), NaHCO3 (24.9), and D-glucose (11.1) gassed with O2-CO2. 95%-5%. The base of the bladder was then cut into strips 4-to 5-mm wide and 10-mm long. Then strips were pretensioned (0.25-0.5 g) and after 30 min of equilibration were contracted with an additional 60 mM KCl and again were allowed to equilibrate. Compounds were administered directly into the tissue bath. All compounds produced a concentration-dependent relaxation of isolated rat bladder strips.
Asunto(s)
Guanidina/farmacología , Hidrocarburos Fluorados/farmacología , Relajación Muscular/efectos de los fármacos , Pinacidilo/farmacología , Vejiga Urinaria/efectos de los fármacos , Adenosina Trifosfato/metabolismo , Animales , Relación Dosis-Respuesta a Droga , Femenino , Guanidina/análogos & derivados , Técnicas de Cultivo de Órganos , Pinacidilo/análogos & derivados , Canales de Potasio/metabolismo , Ratas , Vejiga Urinaria/metabolismoRESUMEN
In the experiments, using isolated, perfused according to Langendorff heart of guinea pig, was investigated the effect of flokalin, a new fluor-containing opener of ATP sensitive channels (K(ATP)), upon the functioning of the heart. It was shown, that flokalin in a dose dependent manner dilates coronary vessels, decreases final diastolic pressure in the left ventricle and the rate of extrasystoles. Flokalin does not significantly affect the developing pressure in the left ventricle, max and min dP/dt, the frequency of cardiac contractions. 5-hydroxydecanoic acid (5-HD), an inhibitor of KATP in the mitochondrial membranes, increases the developing pressure in the left ventricle, max and min dP/dt, perfusion pressure in the coronary vessels. Simultaneously the final diastolic pressure in the left ventricle is decreased. Inhibition of K(ATP) channels in the mitochondrial membrane does not affect the vasodilatory effects of flokalin in the coronary vessels. This data, under the condition of specific action of 5-HD, permits us to suppose the participation of sarcolemmal KATP channels in the mentioned processes. It was shown that inhibition of mitochondrial K(ATP) channels results in decrease of the final diastolic pressure in the left ventricle and can enhance the effect of flokalin upon the final diastolic pressure, thus urging the idea of the leading role of sarcolemmal K(ATP) channels in the mentioned above processes.