RESUMEN
For a laboratory discharge initiated in a long air gap by a microsecond megavolt pulse, we simultaneously register wideband high-frequency microwave and hard-x-ray emissions and thoroughly analyze the temporal relationship of the emissions depending on the discharge evolution. The temporal structure of microwave radiation is found to consist of numerous short intense bursts with high-frequency components. We directly show that x-ray and microwave emissions can appear almost synchronously in the discharge but only when a complex net of countless plasma channels forms and spans the entire discharge gap. The channel formation is closely related to the intense development of multiple streamers.
RESUMEN
Carbon monoxide (CO) is one of a family of gas transmitters. In this article we present the results of mechanographic investigations of the mechanisms of CO action on a rat thoracic aorta segments. We found that relaxing effect of CO donor CORM-2 on vascular smooth muscles is mediated mainly by opening of voltage-dependent potassium channels in smooth muscle cells: 4-aminopyridine, blocking these channels, almost completely eliminated the CO-induced vasorelaxation of the segments precontracted by depolarization of the smooth muscle cells membranes with high potassium (30 mM KCl) solution or by phenylephrine (10 microM). For the first time we documented that CORM-2 reduces the nicardipine-sensitive input of 45Ca2+ in freshly isolated aorta cells. There are reasons to suggest that the L-type voltage-dependent calcium channels of vascular smooth muscle cells are another target for CO, which is implemented in the relaxing effect of this gas transmitter. Additional research is needed to determine the influence of ruthenium complexes (Ru(II)) on phenomenology of carbon monoxide effects.
Asunto(s)
Canales de Calcio Tipo L/metabolismo , Calcio/metabolismo , Monóxido de Carbono/farmacología , Contracción Muscular/efectos de los fármacos , Músculo Liso Vascular/efectos de los fármacos , Canales de Potasio con Entrada de Voltaje/metabolismo , Animales , Aorta/efectos de los fármacos , Aorta/fisiología , Radioisótopos de Calcio , Monóxido de Carbono/metabolismo , Activación del Canal Iónico/efectos de los fármacos , Activación del Canal Iónico/fisiología , Masculino , Contracción Muscular/fisiología , Músculo Liso Vascular/fisiología , Compuestos Organometálicos/administración & dosificación , Compuestos Organometálicos/metabolismo , Fenilefrina/farmacología , Canales de Potasio con Entrada de Voltaje/agonistas , Canales de Potasio con Entrada de Voltaje/antagonistas & inhibidores , Cloruro de Potasio/farmacología , Ratas , Ratas Wistar , Transducción de Señal/efectos de los fármacos , Técnicas de Cultivo de Tejidos , Vasodilatación/efectos de los fármacos , Vasodilatación/fisiologíaRESUMEN
Contractile responses of airways segments of porpoises inhaling nanopowder CoFe2O4 were stidued by means of a mechanographic method. Inhalation of the nanosize particles of CoFe2O4 in vivo and in vitro testing the nanomaterial on isolated smooth muscles led to potentiation histaminergic, cholinergic contractile activity in airways of porpoises and to strengthening of adrenergic relaxing answers. Nanosize particles vary amplitude of hyperpotassium reductions in smooth muscle segments of airways similarly to the effect of depolymerizing drug colchicine.
Asunto(s)
Bronquios , Cobalto/efectos adversos , Compuestos Férricos/efectos adversos , Contracción Muscular/efectos de los fármacos , Músculo Liso/efectos de los fármacos , Nanopartículas/efectos adversos , Animales , Bronquios/efectos de los fármacos , Cobalto/farmacología , Compuestos Férricos/farmacología , Cobayas , Masculino , Contracción Muscular/fisiología , Músculo Liso/fisiología , Nanopartículas/administración & dosificación , Tráquea/efectos de los fármacos , Tráquea/fisiologíaRESUMEN
Influence of modulation of cytoskeleton by colchicine, vinblastine and cytochalasine B on contractile reactions of smooth muscles has been investigated by mechanographical method, by the methods of the double sucrose gup junction. Ratio F/G-actin in smooth muscle cells defined a method of a fluorescent microscopy. Microfilaments in a greater degree than microtubule are involved in regulation of reductions caused by hyperpotassic-induced reductions of membrane of smooth muscle segments of the rat aorta and generation of action potentials and reductions smooth muscle cells from guinea pig urethra. Reductions of vascular segments of aorta in rats caused by a hyperosmotic solution depend on condition of microfilaments and microtubules, whereas reductions in isoosmotic striction cells depend on condition of microfilaments. The last are involved in mechanisms of phenylephrine influence on mechanical strain of vascular segments of the rat aorta. Contrary to that, microtubules are involved in stimulation by phenylephrine electric and contractile activity the smooth muscle cells guinea pig urethra. Oppressiof contractile activity of smooth muscle segments of the rat aorta is cAMP-mediated and depends on condition of microfilaments of cytoskeleton, while action potentials and reductions smooth muscle cells of a ureter depend on condition of microtubules.
Asunto(s)
Citoesqueleto de Actina/fisiología , Potenciales de Acción/fisiología , Microtúbulos/fisiología , Contracción Muscular/fisiología , Músculo Liso/fisiología , Citoesqueleto de Actina/efectos de los fármacos , Citoesqueleto de Actina/metabolismo , Actinas/metabolismo , Potenciales de Acción/efectos de los fármacos , Animales , Aorta/efectos de los fármacos , Aorta/metabolismo , Aorta/fisiología , Colchicina/farmacología , AMP Cíclico/metabolismo , Citocalasina B/farmacología , Cobayas , Técnicas In Vitro , Microscopía Fluorescente , Microtúbulos/efectos de los fármacos , Microtúbulos/metabolismo , Contracción Muscular/efectos de los fármacos , Músculo Liso/efectos de los fármacos , Músculo Liso/metabolismo , Músculo Liso Vascular/efectos de los fármacos , Músculo Liso Vascular/metabolismo , Músculo Liso Vascular/fisiología , Cloruro de Potasio/farmacología , Ratas , Moduladores de Tubulina/farmacología , Uréter/efectos de los fármacos , Uréter/metabolismo , Uréter/fisiología , Vinblastina/farmacologíaRESUMEN
The adrenergic contractile responses of smooth muscles in the vascular wall of guinea pig pulmonary arteries were studied during ovalbumin sensitization. Sensitization was followed by inhibition of contractile responses to an alpha-adrenoceptor agonist mesatone, prevented endothelium-derived relaxation, and potentiated the contractile response to isoproterenol. Administration of a beta-adrenoceptor agonist isoproterenol potentiated the increase in mechanical strain of smooth muscles in the pulmonary artery precontracted with high-potassium Krebs solution. Removal of the endothelium had no effect on the contractile response of smooth muscle segments from the pulmonary artery of intact and sensitized guinea pigs to b-adrenergic influences. The contractile responses of smooth muscles of the pulmonary artery are associated with activity of the cAMP-dependent signal system and play a role in the pathogenesis of ventilation-perfusion disturbances during atopic inflammation.
Asunto(s)
Agonistas Adrenérgicos beta/farmacología , Músculo Liso Vascular/efectos de los fármacos , Ovalbúmina/administración & dosificación , Arteria Pulmonar/efectos de los fármacos , Animales , Cobayas , Técnicas In Vitro , Isoproterenol/farmacología , Soluciones Isotónicas/farmacología , Contracción Muscular/efectos de los fármacos , Relajación Muscular/efectos de los fármacos , Músculo Liso Vascular/inmunología , Músculo Liso Vascular/fisiología , Ovalbúmina/inmunología , Arteria Pulmonar/fisiologíaRESUMEN
Influence of exogenous nitroso-glutatyon on intensity of oxidizing processes in smooth muscles of colon and bronchial tubes in intact and atopic sensitised porpoises (guinea pigs) was studied. In sensitised porpoises, antioxidant protection has been initially reduced against the background of increased maintenance of products of oxidizing that reflects a picture of oxidizing damage and can be associated with an inflammatory process. In incubation with nitroso-glutatyon, a decrease in activities of syperoxiddismutase and catalase is marked and, in sensitised animals, this effect has been expressed to a lesser degree. Syperoxiddismutase and catalase are antioxidant for the enzymes participating in protection of cells from free-radical damage. A dose-dependence decrease in activity catalase and syperoxiddismutase is defined by a parity of the enzymes participating in disintegration of nitrosoglutatyon and the enzymes which have kept antioxidant activity.
Asunto(s)
Catalasa/metabolismo , Miocitos del Músculo Liso/efectos de los fármacos , Donantes de Óxido Nítrico/farmacología , Estrés Oxidativo , S-Nitrosoglutatión/farmacología , Superóxido Dismutasa/metabolismo , Animales , Catalasa/análisis , Cobayas , Miocitos del Músculo Liso/enzimología , Superóxido Dismutasa/análisisRESUMEN
Influence of Na+,K+,2Cl(-)-cotransport and chloride permeability of the cell membrane on electrically-induced action potential and contraction of smooth muscle cells from guinea pig ureter was examined with the methods of the double sucrose gap junction. Mesatone (10 microM) and histamine (10 microM) induced prolongation of the action potential and elevation of smooth muscle cell contraction, whereas hyperosmic medium (+150 mM sucrose), and recovery of solution osmolality in hyposmic condition (70 mM NaCl) after a single contraction. Inhibitor Na+,K+,2Cl(-)-cotransport bumetanide (10 microM) and chloride permeability blockers niflumic acid (10-100 microM) and SITS (10-500 microM) attenuated stimulating effects of mesatone, histamine and hyperosmic medium. In opposite to adenylate cyclase activation with forskolin (1 microM), guanylate cyclase activation with sodium nitroprusside (SN, 100 microM) decreased both inhibitory action of bumetanide, niflumic acid and activating effects of mesatone, histamine on action potential and elevation contraction of smooth muscle cells. Influence of forskolin rather and not SN on AP and SMC C was inhibited with tetraethylammonium (5 mM). These results suggest that influence of Na+,K+,2Cl(-)-cotransport on electrical and contractil properties of ureter smooth muscle cells is mediated by stimulation of Ca(2+)-activated chloride permeability of the cell membrane and modulated by intracellular cGMP, but not triggered by Ca2+ release from sarcoplasmic reticulum.
Asunto(s)
Permeabilidad de la Membrana Celular/efectos de los fármacos , Histamínicos/farmacología , Histamina/farmacología , Contracción Muscular/efectos de los fármacos , Miocitos del Músculo Liso/metabolismo , Fenilefrina/farmacología , Simportadores de Cloruro de Sodio-Potasio/metabolismo , Uréter/metabolismo , Vasoconstrictores/farmacología , Potenciales de Acción/efectos de los fármacos , Animales , Cloruros/metabolismo , Cobayas , Miocitos del Músculo Liso/citología , Uréter/citologíaRESUMEN
Features of the pharmacological sensitivity of smooth muscles in the walls of arteries of the lesser circulation circle in rabbits with respect to cholinergic, histaminergic, and adrenergic agents, as well as the influence of endothelium on the realization of contractile response to these agents have been investigated in rabbits. A special feature in the cholinergic relaxation of smooth muscles of a pulmonary artery is a two-componential character of the dose dependence. The low-threshold component of the relaxant action of pilocarpine exhibits the endothelium-dependent character. An important feature of the contractile reaction to histaminergic action is a direct contractile effect of histamine, which is not observed in vessels of the greater circulation circle. Endothelium produces an inhibiting effect on the histaminergic contractility. The basic feature in the response to adrenergic action is the beta-adrenergic contractility effect. Activation of the cAMP-dependent alarm system in smooth muscles of the pulmonary arteries leads to a constrictive effect. The established features of the pharmacological sensitivity of smooth muscles of the artery walls of the lesser circulation circle are important for the clinical pharmacology.
Asunto(s)
Músculo Liso Vascular/efectos de los fármacos , Neurotransmisores/farmacología , Arteria Pulmonar/efectos de los fármacos , Animales , Contracción Muscular/efectos de los fármacos , Circulación Pulmonar/efectos de los fármacos , Conejos , Vasoconstricción , VasodilataciónRESUMEN
Now sireos problem of pulmonology there are the diseases connected with infringement of coordinated regulation of a tone of smooth muscles of vessels and airways of ways that conducts to dissociation of parameters haemodinamyc and ventilation of lungs and as consequence, to infringement airwave-perfusion attitudes. In the review features humoral regulation contractile activity of smooth muscles of vessels of a small circle of blood circulation, a role of endocellular alarm systems in these mechanisms, and endothelium, as the local modulator endocrine functions are considered. Disgusting muscles of a small circle are distinguished from the main vessels of the big circle of blood circulation with predisposition to the raised mechanical pressure. In spite of the fact that endothelium renders modulating relaxe influence on contractile answers of smooth muscles of vessels of a venous and arterial small circle of blood circulation at action corresponding vasoconstriction, pulmonary veins are capable to endothelium-dependent dilatation to a lesser degree, in comparison with pulmonary arteries. And, on the contrary, in absence endothelium, they are characterized with high sensitivity to vasopression to substances--serotonin, histamine, phenylephrine. Features of regulation smooth muscle pressure pulmonary an artery are shown in contractile reactions of its isolated segments in reply to influence beta-adreno agonist--isoprotherenol and phosphoesterase inhibitors. Though, increase in endocellular concentration cyclic nucleotides (cAMP and\or cGMP), on the standard representations, cannot explain growth of a mechanical pressure of smooth muscles, apparently, in contractile reactions of a pulmonary artery to influence biologically and physiologically active substances interfere more complex mechanisms in which basis processes of interaction of smooth muscles cells lay, endothelium and cells of a microenvironment. Finding-out of the contribution cyclic nucleotides in these processes demands the further researches.
Asunto(s)
Circulación Sanguínea/fisiología , Endotelio Vascular/fisiología , Contracción Muscular/fisiología , Músculo Liso Vascular/fisiología , Animales , Endotelio Vascular/metabolismo , Humanos , Músculo Liso Vascular/metabolismo , Receptores de Superficie Celular/metabolismo , Transducción de Señal/fisiologíaRESUMEN
Experiments on isolated rat liver perfused with Ringer-Krebs bicarbonate buffer showed that stimulation of delta-opiate receptors in this organ increases bile flow rate and taurocholate secretion. Stimulation of micro-opiate receptors decelerated bile production and inhibited taurocholate secretion. Acceleration of bile production and stimulation of taurocholate secretion under the influence of dalargin is probably related to its interaction with delta-opiate receptors in the liver.
Asunto(s)
Bilis/metabolismo , Hígado/fisiología , Receptores Opioides delta/fisiología , Receptores Opioides mu/fisiología , Animales , Encefalina Ala(2)-MeFe(4)-Gli(5)/farmacología , Leucina Encefalina-2-Alanina/análogos & derivados , Leucina Encefalina-2-Alanina/farmacología , Técnicas In Vitro , Naloxona/farmacología , Ratas , Receptores Opioides delta/efectos de los fármacos , Ácido Taurocólico/metabolismoRESUMEN
Ifluence of intraperitoneal delta, mu and kappa opioid agonists on bile secretion and composition stimulated by cholecystokinin was studied in white rats. All opioids under study decreased the secretory response of liver to cholecystokinin. It is supposed that opioidergic regulation alter bile secretion in an opposite manner depending on base secretory level.
Asunto(s)
Bilis/metabolismo , Colecistoquinina/metabolismo , Hígado/metabolismo , Péptidos Opioides/farmacología , Receptores Opioides/agonistas , Animales , Masculino , RatasRESUMEN
The role of nitric oxide (NO) and its implication in intracellular and intercellular signaling pathways attract an attention of many research teams up to now. Away of its signaling functions. NO is considered as one of the key molecules in maintenance of balance between the physiological and pathological processes due to cytoprotective and cytotoxic functions of this molecule. In this regard, elucidation of the NO-dependent mechanisms, involved into the physiological processes and pathophysiological reactions, remains an urgent problem of conntemporary biology and medicine. Analysis of obtained results establishes a relative contribution of electro- and pharmaco-mechanical coupling mechanisms in NO-dependent regulation of smooth muscle cels (SMC) functions. The authors show that elevation of intracellular Ca2+ concentration by biologically active substances promotes relaxing effect of NO through both voltage-dependent and -independent intracellular mechanisms of calcium redistribution. Namely the peculiarities of considered mechanisms in each certain type of SMCs cause the final direction of alterations in contractility and membrane potential. It has been shown that voltage-dependent effects of NO are mediated by suppression of calcium and/or sodium components and modulation of Ca2+ -dependent and ATP-seisitive potassium components of SMC membrane permeability, Voltage-independent NO control of mechanical smooth muscles activity mainly is mediated by 1) modulation of protein kinase C (PK-C) branch of calcium signaling system, 2) ratio of cyclic nucleotides intracellular concentrations (cGMP/cAMP), and 3) directional mode of electrosilent Na+, K+, 2Cl- -cotransport. Our results show that the features of the myogenic effects of NO are caused by the peculiarities of PK-C operation in SMC.
Asunto(s)
Contracción Muscular/fisiología , Músculo Liso/fisiología , Óxido Nítrico/fisiología , Transducción de Señal , Animales , Calcio/metabolismo , Señalización del Calcio , Cloruros/metabolismo , AMP Cíclico/metabolismo , GMP Cíclico/metabolismo , Conductividad Eléctrica , Potenciales de la Membrana , Músculo Liso/metabolismo , Potasio/metabolismo , Proteína Quinasa C/metabolismo , Sodio/metabolismoRESUMEN
The effect of Na(+),K(+),2Cl(-) cotransport inhibitor bumetanide on action potentials and contractions of smooth muscle cells in the ureter of guinea pigs evoked by electrical stimulation was studied by the method of double sucrose bridge. Bumetanide (10-100 microM) dose-dependently suppressed action potential and contractions of smooth muscle cells induced by 1-10 microM histamine, 10 microM mesatone, 5 mM tetraethylammonium, and 100 microM sodium nitroprusside. Our findings suggest that test substances modulate Na(+),K(+),2Cl(-) cotransport in smooth muscle cells.
Asunto(s)
Potenciales de Acción/fisiología , Bumetanida/farmacología , Contracción Muscular/fisiología , Miocitos del Músculo Liso/efectos de los fármacos , Simportadores de Cloruro de Sodio-Potasio , Uréter/anatomía & histología , Animales , Estimulación Eléctrica , Cobayas , Técnicas In Vitro , Miocitos del Músculo Liso/metabolismo , Nitroprusiato/farmacología , Bloqueadores de los Canales de Potasio/farmacología , Inhibidores del Simportador de Cloruro Sódico y Cloruro Potásico , Simportadores de Cloruro de Sodio-Potasio/metabolismo , Tetraetilamonio/farmacología , Uréter/metabolismo , Vasodilatadores/farmacologíaRESUMEN
Exposure to X-rays causes pronounced morphofunctional changes in basal cells and modulates linear cellularity in the epidermal basal layer in guinea pigs. Radiosensitivity of skin basal cells of different location is different: the most pronounced morphofunctional changes were observed in the skin of the head (cheek) and abdomen.
Asunto(s)
Tamaño de la Célula , Células Epidérmicas , Epidermis/efectos de la radiación , Tolerancia a Radiación , Animales , Citofotometría , Cobayas/anatomía & histología , Humanos , Masculino , Microscopía Electrónica , Rayos XRESUMEN
The results of the membrane potential measurements (by the double sucrose gap junction technique) and the smooth muscle tension determination (by the mechanical force measurements) in the rat aorta showed that vinpocetine potentiates the effect of sodium nitroprusside and nitroglycerin on the smooth muscle cells. In the concentration range of 2-20 microM, vinpocetine produced a dose-dependent inhibition of the Ca2+ conductivity of the membrane and decreased the smooth muscle contractility response. At a concentration of 1 microM, the drug acted as an inhibitor of the phosphodiestherase (PDE) activity and produced the effects similar top those of dibutyryl-cGMP (rather than dibutyryl-cAMP). In the presence of 10 microM of Methylene Blue (an inhibitor of the soluble fraction of guanylate cyclase), the cGMP-dependent effects of vinpocetine were suppressed on the background of 100 microM of sodium nitroprusside, but retained on the background of 10 microM of 3-isobutyl-1-methylxanthine (IBMX), a nonspecific PDE inhibitor. IBMX acted like dibityryl-cGMP and activated the K+ conductivity of the membrane. It is suggested that cGMP-dependent effects of vinpocetine are related to its action upon the Ca2+ and Na+ and (but not K+) conductivity and to the cGMP-induced increase in the contribution of sarcoplasmic calcium to the contractile response.
Asunto(s)
GMP Cíclico/metabolismo , Miocitos del Músculo Liso/efectos de los fármacos , Inhibidores de Fosfodiesterasa/farmacología , Alcaloides de la Vinca/farmacología , Potenciales de Acción/efectos de los fármacos , Animales , Arterias/citología , Calcio/metabolismo , Membrana Celular/efectos de los fármacos , Membrana Celular/metabolismo , Membrana Celular/fisiología , Cobayas , Técnicas In Vitro , Transporte Iónico , Contracción Muscular/efectos de los fármacos , Músculo Liso Vascular/citología , Músculo Liso Vascular/fisiología , Miocitos del Músculo Liso/metabolismo , Miocitos del Músculo Liso/fisiología , Potasio/metabolismo , Ratas , Sodio/metabolismo , Uretra/citologíaRESUMEN
Heterogeneity of the cGMP-dependent contractility effects of the smooth cells (SMC) was shown in guinea pig ureter by the methods of the double sucrose gap junction. Sodium nitroprusside (SN, 0.1-100 microM) relaxed the high-K+ depolarisationprecontracted SMC but strengthened the SMC constriction triggered by electrical stimulation. In taenia coli, SN or nitroglycerin in the same concentration ranges depressed the electrical or mechanical activity of the SMC and relaxed the SMC, precontracted by depolarization in high-K+ medium. The inhibitor of the phosphodiesterases vinpocetine (1 microM) contributed to the activating effect of SN; the inhibitor of the soluble guanilatcyclase Methilen Blue (10 microM) depressed it. Histamine and mesotone (1-10 microM) increased the action potential and constriction of the SMC triggered by electrical stimulation but decreased the effect of SN. The activator of the protein kinase C (PK-C) phorbol miristoyl-13-acetyl (0.5 microM) changed direction of the SN effects inhibiting both the parameters of an action potential and of the SMC constriction. The pre-treatment with the inhibitor of PK-C calphostin C (0.1 microM) additionally depressed the effects of SN, increasing SMC constriction, especially in the presence of histamine and mesatone. We suggest that c-GMP depressed activity of the PK-C by independent mechanisms operating in SMC.
Asunto(s)
GMP Cíclico/fisiología , Contracción Muscular/fisiología , Músculo Liso/fisiología , Proteína Quinasa C/fisiología , Potenciales de Acción/efectos de los fármacos , Potenciales de Acción/fisiología , Animales , Colon/efectos de los fármacos , Colon/enzimología , Colon/fisiología , Estimulación Eléctrica , Inhibidores Enzimáticos/farmacología , Cobayas , Técnicas In Vitro , Contracción Muscular/efectos de los fármacos , Músculo Liso/efectos de los fármacos , Músculo Liso/enzimología , Nitroglicerina/farmacología , Nitroprusiato/farmacología , Proteína Quinasa C/antagonistas & inhibidores , Uréter/efectos de los fármacos , Uréter/enzimología , Uréter/fisiologíaRESUMEN
The effect of nibentan (2.5 and 25 muM) on extrasystolic and post-extrasystolic contraction of isolated and perfused papillary muscle was studied. The muscle contracted in an isometric regimen at a rate of external electrical stimulation of 0.5 Hz in a temperature-stabilized chamber (36.0+0.5 degrees C). The extrasystolic contraction was induced with an extra electrical pulse applied 0.25 sec after the regular stimulus. Nibentan decreased the amplitude of extrasystolic contraction in a dose-dependent manner. At the same time, the effect of nibentan on extrasystolic contraction practically did not depend on its concentration. It is concluded that nibentan produces a dose-dependent effect on excitability of rat ventricular myocardium, and in parallel improves calcium-accumulating capacity of the sarcoplasmic reticulum in cardiomyocytes.
Asunto(s)
Antiarrítmicos/farmacología , Benzamidas/farmacología , Músculos Papilares/efectos de los fármacos , Animales , Calcio/metabolismo , Relación Dosis-Respuesta a Droga , Electrofisiología , Ventrículos Cardíacos/metabolismo , Masculino , Contracción Muscular/efectos de los fármacos , Ratas , Ratas Wistar , Retículo Sarcoplasmático/metabolismo , Sístole , TemperaturaRESUMEN
Function of sarcoplasmic reticulum was studied in rat papillary muscles treated with amiodarone. An extra stimulus (0.5 Hz) was delivered to the muscle 0.225 sec after application of a regular stimulus. Postextrasystolic potentiation was evaluated in control myocardial samples and samples treated with amiodarone. The preparation significantly increased all the parameters of postextrasystolic contraction. It was concluded that amiodarone potentiates the ability of sarcoplasmic reticulum to accumulate Ca2+ ions.
Asunto(s)
Amiodarona/farmacología , Antiarrítmicos/farmacología , Corazón/efectos de los fármacos , Retículo Sarcoplasmático/efectos de los fármacos , Animales , Corazón/fisiología , Masculino , Contracción Miocárdica/efectos de los fármacos , Ratas , Ratas Wistar , Retículo Sarcoplasmático/fisiologíaRESUMEN
Muscle tension recording was used to study adrenergic contractile reactions of pulmonary artery smooth muscles in rabbits. Stimulation of alpha-adrenoceptors induced contraction of pulmonary artery smooth muscle cells. Endothelium partially inhibited the contractile effect of alpha-adrenoceptor agonists. Activation of smooth muscle beta-adrenoceptors in pulmonary arteries produced a dual dose-dependent effect (relaxation at agonist concentrations of 10 nM-1 muM and contraction at concentrations above 10 muM). The contractile effect of beta-adrenoceptor activation in smooth muscle cells is a specific feature of pulmonary arteries probably related to peculiarities of cAMP-signaling in these cells.