RESUMEN
Angiotensin converting enzyme (ACE) inhibitors have cardioprotective effects in different species including human. This cardioprotective effect is mainly due to the inhibition of bradykinin (BK) degradation rather than inhibition of the conversion of angiotensin I to angiotensin II. Bradykinin, a nonapeptide, has been considered to be the potential target for various enzymes including ACE, neutral endopeptidase 24.11, carboxypeptidase M, carboxypeptidase N, proline aminopeptidase, endopeptidase 24.15, and meprin. In the present study, the coronary vascular beds of Sprague Dawley rat isolated hearts were perfused (single passage) with Krebs solution alone or with different concentrations of BK i.e. 2.75x10(-10), 10(-7), 10(-6) and 10(-5) M solution. Percent degradation of BK was determined by radioimmunoassay. The degradation products of BK after passing through the isolated rat-hearts were determined using RP-HPLC and mass spectroscopy. All the four doses of BK significantly decreased the perfusion pressure during their passage through the hearts. The percentage degradation of all four doses was decreased as the concentration of drug was increased, implying saturation of a fixed number of active sites involved in BK degradation. Bradykinin during a single passage through the hearts degraded to give [1-7]-BK as the major metabolite, and [1-8]-BK as a minor metabolite, detected on HPLC. Mass spectroscopy not only confirmed the presence of these two metabolites but also detected traces of [1-5]-BK and arginine. These findings showed that primarily ACE is the major cardiac enzyme involved in the degradation of bradykinin during a single passage through the coronary vascular of bed the healthy rat heart, while carboxypeptidase M may have a minor role.
Asunto(s)
Bradiquinina/metabolismo , Cardiotónicos/metabolismo , Miocardio/metabolismo , Animales , Bradiquinina/farmacología , Cardiotónicos/farmacología , Vasos Coronarios/efectos de los fármacos , Proteínas Ligadas a GPI , Técnicas In Vitro , Masculino , Metaloendopeptidasas/metabolismo , Miocardio/enzimología , Neprilisina/metabolismo , Peptidil-Dipeptidasa A/metabolismo , Perfusión , Ratas , Ratas Sprague-DawleyRESUMEN
It has been postulated that the mammary kinin system may play a role in modulating mammary blood flow. Until the present study, the local release of bradykinin (BK) or other kinin system constituents into the mammary vasculature had not been reported and there were also conflicting findings on the action of BK on udder vasculature. Udders were removed from healthy lactating cows at slaughter. Pairs of ipsilateral quarters were perfused with Tyrode solution through the external pudendalis artery and drained via the cranial superficial epigastric vein. Mammary secretion was collected through teat cannulae. The perfusion pressure was linearly related to perfusate flux between 60 and 210 ml min(-1) and the flow rate was adjusted (110-150 ml min(-1)) to give a basal pressure of 85 mmHg. PO2, PCO2 and pH in the venous effluent perfusate stabilised at 157 +/- 10 mmHg, 50.1 +/- 2.4 mmHg and 7.1 +/- 0.03, respectively. The venous effluent contained immunoreactive BK and BK precursor, tissue kallikrein activity, and bradykinin-destroying enzyme. The concentration of BK stabilised at 378 +/- 48 pg (ml perfusate)(-1), that of trypsin-activated BK precursor was 679 +/- 59 pg BK equivalents ml(-1) and that of tissue kallikrein, measured as cleavage of D-Val.Leu.Arg-p-nitroanilide (D-Val.Leu.Arg-pNA), was 5.5 +/- 1.7 nmol p-NA h(-1) ml(-1). Arterial infusion of phenylephrine (0.49-490 microM) produced increases in perfusion pressure (vasoconstriction). Acetylcholine (ACh) (0.55-55 microM) and BK (0.1-10 microM) produced only vasodilatation. BK (EC50 = 1.00+/-0.04 microM) was a more potent vasodilator than ACh (EC50 = 9.57+/-0.49 microM). The basal BK concentration was 250 times below the threshold for vasoactivity. The udder produced a milk-like secretion, which was dependent on perfusate flow and contained a concentration of BK which remained unchanged from 60 to 180 min of perfusion (231 +/- 31 pg ml(-1)) unlike that in the venous effluent which doubled between 60 and 120 min. Thus, in addition to its secretion into milk, BK, together with its precursor and tissue kallikrein, is continuously released into the vasculature of the isolated, perfused, lactating bovine udder.
Asunto(s)
Bradiquinina/metabolismo , Glándulas Mamarias Animales/irrigación sanguínea , Glándulas Mamarias Animales/fisiología , Acetilcolina/farmacología , Animales , Bradiquinina/farmacología , Bovinos , Relación Dosis-Respuesta a Droga , Femenino , Calicreínas/metabolismo , Lactancia , Glándulas Mamarias Animales/metabolismo , Leche/metabolismo , Perfusión , Fenilefrina/farmacología , Precursores de Proteínas/metabolismo , Flujo Sanguíneo Regional/efectos de los fármacos , Vasoconstrictores/farmacología , Vasodilatación/fisiologíaRESUMEN
A bioassay-guided technique has been used to isolate anti-inflammatory compounds from the dried rhizomes of Polygonum bistorta, for structural identification. Anti-inflammatory activity was detected using the carrageenan-induced rat paw oedema. Two compounds were isolated which significantly suppressed the inflammatory response. Spectral data from EIMS and NMR together with some physical characteristics revealed the identities of the two active compounds as 5-glutinen-3-one and friedelanol. The results indicate that these two compounds largely account for the anti-inflammatory actions of the rhizomes of P. bistorta.
Asunto(s)
Antiinflamatorios no Esteroideos/aislamiento & purificación , Extractos Vegetales/aislamiento & purificación , Polygonaceae/química , Animales , Antiinflamatorios no Esteroideos/química , Antiinflamatorios no Esteroideos/farmacología , Espectroscopía de Resonancia Magnética , Espectrometría de Masas , Extractos Vegetales/química , Extractos Vegetales/farmacología , Ratas , Ratas Sprague-DawleyRESUMEN
The kinin peptides are released during inflammation and are amongst the most potent known mediators of vasodilatation, pain and oedema. Despite early reports of the presence of kinins in milk, no previous study has investigated the role of the kinin system in bovine mastitis. The present study indicated that mastitis was accompanied by raised levels of bradykinin (BK) in milk and the increased levels of BK correlated with the severity of mastitis. Raised BK levels in mastitic milk were not dependent on the presence of inflammatory cells, nor were they secondary to changes in blood levels of BK. In milk from sub-clinically inflamed quarters, BK was raised in those milks where Staphylococcus aureus (S. aureus) was isolated but not in those milks where no pathogen was isolated. Increasing S. aureus artificially, also caused an increase in the milk BK. Increases in milk BK were not restricted only to the mastitic quarters of the udder. In udders in which mastitis was detected in one or more quarters, BK increases were also detected in the apparently uninvolved quarters.
Asunto(s)
Bradiquinina/metabolismo , Mastitis Bovina/metabolismo , Proteínas de la Leche/metabolismo , Infecciones Estafilocócicas/metabolismo , Animales , Bradiquinina/sangre , Bovinos , Recuento de Células , Femenino , Glándulas Mamarias Animales/microbiología , Mastitis Bovina/microbiología , Leche/química , Leche/microbiología , Proteínas de la Leche/análisis , Infecciones Estafilocócicas/microbiología , Staphylococcus aureus/patogenicidadRESUMEN
The present study was undertaken to investigate the involvement of kinins in the cardiovascular- and respiratory effects of LQQ venom. Blood pressure, heart rate, electrocardiogram (ECG) and respiration were studied in anaesthetised rabbits, in the presence and absence of aprotinin and icatibant, a B2 bradykinin antagonist. Plasma bradykinin concentrations were also measured following venom injection. LQQ venom caused a triphasic effect on blood pressure comprising an immediate fall, a pronounced rise and a progressive decline until death. Bradycardia, myocardial damage, arrhythmias, respiratory distress and pulmonary oedema were also exhibited. Pretreatment with aprotinin attenuated the venom-induced hypotension, bradycardia, ECG and respiratory changes and prolonged survival. Pretreatment of atropinized animals with icatibant gave similar protection. In animals treated with LQQ venom, plasma bradykinin was significantly higher than controls, although there was considerable inter-animal variation in plasma kinin concentrations and the elevation was seen relatively late after venom administration. The data provides some support for the hypothesis that kinins are involved in the cardiovascular and lethal effects of LQQ venom in rabbits.
Asunto(s)
Presión Sanguínea/efectos de los fármacos , Frecuencia Cardíaca/efectos de los fármacos , Venenos de Escorpión/farmacología , Antagonistas Adrenérgicos beta/administración & dosificación , Antagonistas Adrenérgicos beta/farmacología , Animales , Aprotinina/administración & dosificación , Aprotinina/farmacología , Bradiquinina/administración & dosificación , Bradiquinina/análogos & derivados , Bradiquinina/sangre , Bradiquinina/farmacología , Antagonistas de los Receptores de Bradiquinina , Electrocardiografía/efectos de los fármacos , Péptidos y Proteínas de Señalización Intercelular , Péptidos/administración & dosificación , Péptidos/farmacología , Conejos , Respiración/efectos de los fármacos , Venenos de Escorpión/administración & dosificación , Inhibidores de Serina Proteinasa/farmacologíaRESUMEN
The aim of this study was to detect the possible release from the ischemic rabbit myocardium of a factor capable of modulating the release of endothelin-1 (ET-1) from the peripheral vasculature. Isolated rabbit hearts were perfused on a Langendorff apparatus so that part of the coronary effluent was pumped directly into the arterial supply of isolated ears. Mean ET-1 outflow from ears perfused with fresh Krebs was 4.33 +/- 0.72 pg/min; from ears perfused with coronary effluent it was 84.3% less. This still represented net ET-1 production in the ear (venous/arterial ET-1 concentration ratio (V/A) = 3.9 +/- 1.2). Myocardial ischemia (30 min) caused a large reduction in ET-1 outflow from the ears and changed net production to net loss (V/A = 0.32 +/- 0.17). Within 2 min of reperfusion the V/A had risen to 6.3 +/- 2.2 and the ET-1 outflow from the ears rose 16-fold. Neither 30-min coronary occlusion nor 2-min reperfusion altered ET-1 concentrations in the coronary effluents. After 60-min reperfusion, ET-1 concentration in coronary effluent rose by 230%. During myocardial ischemia and reperfusion there was no change in pO2, pCO2 or pH in the perfusate supplying the ears. Therefore the changes in ET-1 handling by the ear vasculature must have been induced by a transmissible factor released from the heart.
Asunto(s)
Endotelina-1/metabolismo , Músculo Liso Vascular/metabolismo , Isquemia Miocárdica/metabolismo , Miocardio/metabolismo , Animales , Oído Externo/irrigación sanguínea , Técnicas In Vitro , Masculino , Perfusión , Conejos , Flujo Sanguíneo Regional/fisiologíaRESUMEN
Myocardial ischemia results in the release of a variety of vasoactive substances from coronary vascular endothelial cells and/or from cardiac myocytes. Some of these substances appear to be protective and include nitric oxide and bradykinin. One hypothesis for the pronounced antiarrhythmic effects of preconditioning involves the early generation of bradykinin and, subsequently, nitric oxide. Evidence for early bradykinin release has come from clinical studies involving patients undergoing coronary angioplasty where, in 4 of 5 patients, there was evidence for elevated kinin levels in coronary sinus blood either during balloon inflation (i.e., ischemia) or deflation (reperfusion). The levels reached are sometimes considerable (increases 10-20 fold). The second piece of evidence comes from dogs subjected to a preconditioning stimulus (2 x 5 min periods of ischemia), followed 20 min later by occlusion of the same artery for a 25-min period. This preconditioning procedure markedly reduces ischemia-induced ventricular arrhythmias and, although under resting conditions there was little difference between arterial and coronary sinus bradykinin levels (125 +/- 22 and 157 +/- 41 pg/mL, respectively), there was a marked increase in coronary sinus levels in preconditioned dogs before the prolonged occlusion (637 +/- 293 pg/mL compared with 114 +/- 18 pg/mL in nonpreconditioned dogs); levels at the end of the prolonged occlusion in the preconditioned dogs were also higher (577 +/- 305 pg/mL compared with 162 +/- 34 pg/mL in control dogs). Other evidence for the involvement of bradykinin and nitric oxide comes from studies in which the generation, or effects, of these mediators have been suppressed (e.g., with the bradykinin B2 receptor blocking agent icatibant, with inhibitors of the L-arginine-nitric oxide pathway, and by methylene blue). The conclusion is that early bradykinin release is protective under conditions of ischemia, is presumably enhanced during therapy with angiotensin-converting enzyme (ACE) inhibitors and is suppressed under conditions of endothelial dysfunction.
Asunto(s)
Bradiquinina/metabolismo , Endotelio Vascular/metabolismo , Precondicionamiento Isquémico Miocárdico , Isquemia Miocárdica/metabolismo , Miocardio/metabolismo , Animales , Estimulación Cardíaca Artificial , Perros , Endotelio Vascular/citología , Miocardio/citología , Taquicardia Ventricular/metabolismo , Fibrilación Ventricular/metabolismoRESUMEN
Bradykinin has previously been shown to suppress ET-1 secretion by endothelial cells. In the present study, rat isolated hearts have been perfused with Krebs solution using the Langendorff method. Immunoreactive bradykinin (IRBK) was measured in the perfusate and the basal level was found to be constant for up to 3 h. Ten min perfusions of the hearts with ET-1 at concentrations of 0.2-20 pM produced a dose-related suppression of kinin outflow by over 90% (P < 0.05). At these concentrations ET-1 had no detectable effect on the coronary vasculature or ECG. At 200 pM ET-1 and above, the hearts showed arrhythmias of increasing severity, accompanied at the highest doses by marked coronary constriction and an increase in IRBK outflow.
Asunto(s)
Bradiquinina/metabolismo , Endotelina-1/farmacología , Corazón/efectos de los fármacos , Corazón/fisiología , Animales , Presión Sanguínea/efectos de los fármacos , Relación Dosis-Respuesta a Droga , Electrocardiografía , Endotelina-1/administración & dosificación , Frecuencia Cardíaca/efectos de los fármacos , Técnicas In Vitro , Perfusión , Ratas , Ratas Sprague-DawleyRESUMEN
The release of kinin during 30 min of left descending coronary artery was observed in WKY, SHR and SD rat isolated hearts. The kinin levels were compared with the ECG abnormalities in these strains. It was observed that low level of kinin could not be a reason for increased ECG abnormalities. IRBK in the perfusate was also characterised.
Asunto(s)
Corazón/fisiología , Cininas/metabolismo , Isquemia Miocárdica/fisiopatología , Animales , Bradiquinina/análogos & derivados , Bradiquinina/metabolismo , Electrocardiografía , Técnicas In Vitro , Perfusión , Ratas , Ratas Endogámicas SHR , Ratas Endogámicas WKY , Ratas Sprague-Dawley , Especificidad de la EspecieRESUMEN
BK destroying activity was observed in rat isolated heart perfusates. BK was optimally degraded at pH 8.4 in rat heart. The results indicated that myocardial kinin degradation was due to ACE and a serine protease. These results suggest that bradykinin may have some cardioprotective role during myocardial ischaemia at acidic pH.
Asunto(s)
Lisina Carboxipeptidasa/metabolismo , Isquemia Miocárdica/enzimología , Miocardio/enzimología , Peptidil-Dipeptidasa A/metabolismo , Inhibidores de la Enzima Convertidora de Angiotensina/farmacología , Animales , Aprotinina/farmacología , Bradiquinina/metabolismo , Captopril/farmacología , Ácido Edético/farmacología , Concentración de Iones de Hidrógeno , Técnicas In Vitro , Masculino , Perfusión , Ratas , Ratas Sprague-Dawley , Inhibidores de Serina Proteinasa/farmacologíaRESUMEN
BACKGROUND: Canine ventricles have been reported to contain a cathepsin D-like kininogenase, which might confer protection on the heart during ischaemia. The aim of this study was to investigate the presence and levels of a similar kininogenase in normal and ischaemic rat hearts. METHODS: Aqueous extracts of rat ventricles were tested for the ability to release bradykinin-like immunoreactivity from human low-molecular-weight kininogen and high-molecular-weight kininogen at acidic pHs. The enzymes involved were separated using gel filtration followed by the testing of fractions for cleavage of D-Val-Leu-Arg-pNA and low-molecular-weight kininogen. Extracts from normal and ischaemic ventricles were compared for the ability to release bradykinin-like immunoreactivity from low-molecular-weight kininogen. Kinin levels in mixed venous blood were compared before and after ischaemia. By assessing their effect on isolated oestrous rat uteri and on protease inhibitors, further characterization of acidic kininogenases in the extracts was performed. RESULTS: Extracts of rat ventricles released bradykinin-like immunoreactivity only from low-molecular-weight kininogen. Using the isolated oestrous rat uterus, gel filtration and protease inhibitors, the enzyme involved was identified as a cathepsin D-like enzyme with an optimum pH of 4.7 and a molecular weight of 42.8 +/- 4.9 kDa. It is an arginine amidase and releases bradykinin-like immunoreactivity from low-molecular-weight kininogen. Ischaemia reduced the amount of bradykinin-like immunoreactivity released by the ventricular extract (P < or = 0.05) and increased levels of free kinin in venous blood from the right atrium. CONCLUSION: Rat ventricles contain a cathepsin D-like acidic protease that cleaves low-molecular-weight kininogen to release bradykinin-like immunoreactivity. The acidic protease may protect the heart during ischaemia.
Asunto(s)
Ventrículos Cardíacos/enzimología , Calicreínas/metabolismo , Animales , Bradiquinina/metabolismo , Catepsina D/metabolismo , Femenino , Concentración de Iones de Hidrógeno , Técnicas In Vitro , Masculino , Peso Molecular , Isquemia Miocárdica/enzimología , Miocardio/enzimología , Ratas , Ratas Sprague-Dawley , Útero/metabolismoRESUMEN
The effects of intravenous (i.v.) infusions of exogenous endothelin-1 (ET-1, 0.05 and 0.1 nmol/kg/min) on incidence and severity of ventricular arrhythmias during 30-min period of acute myocardial ischemia were assessed in anesthetized rats. We examined the role of ETA-receptors in the proarrhythmic effects of both exogenous and endogenous ET using the ETA-receptor antagonist, BQ123. Exogenous ET-1 increased the severity and incidence of ischemic arrhythmias dose dependently. Both doses increased the total incidence of ventricular fibrillation (VF: from 30% in controls to 100 and 88% in rats given 0.05 and 0.1 nmol/kg/min ET-1, respectively); the higher dose also increased total arrhythmia count and duration of ventricular tachycardia (VT). BQ123 (10 micrograms/kg/min) completely abolished this proarrhythmic effect of exogenous ET-1. To assess the role of endogenous ET-1 in the genesis of ischemic arrhythmias, we studied the effects of a range of doses of BQ123 (5-100 micrograms/kg/min) on ischemic arrhythmias. Only one dose of BQ123 (10 micrograms/kg/min) attenuated arrhythmias by reducing total ventricular ectopic count (from 1,423 +/- 112 in controls to 677 +/- 159). The highest dose of BQ123 tested (100 micrograms/kg/min) increased arrhythmias by significantly increasing the incidence of irreversible VF (from 25 to 75%). These results suggest that exogenous ET-1 can aggravate ischemia-induced arrhythmias, an effect that is sensitive to ETA-receptor blockade. However, although endogenous ET-1 may make some contribution to the genesis of arrhythmias resulting from coronary occlusion through an action at ETA receptors, the observed proarrhythmic effect of BQ123 at high doses suggests that this may unmask an effect of ET-1 at other receptors.
Asunto(s)
Arritmias Cardíacas/tratamiento farmacológico , Antagonistas de los Receptores de Endotelina , Endotelinas/farmacología , Isquemia Miocárdica/tratamiento farmacológico , Péptidos Cíclicos/farmacología , Anestesia , Animales , Arritmias Cardíacas/etiología , Presión Sanguínea/efectos de los fármacos , Vasos Coronarios/efectos de los fármacos , Electrocardiografía/efectos de los fármacos , Endotelinas/administración & dosificación , Frecuencia Cardíaca/efectos de los fármacos , Infusiones Intravenosas , Masculino , Isquemia Miocárdica/complicaciones , Ratas , Ratas Sprague-DawleyRESUMEN
The aqueous ethanolic extracts of Polygonum bistorta L. Polygonaceae, Guaiacum officinale L. Zygophyllaceae and Hamamelis virginiana L. Hamamelidaceae were screened for anti-inflammatory activity. Administered (100 and 200 mg kg-1, p.o.) before the induction of carrageenan rat paw oedema, extracts of P. bistorta significantly suppressed both the maximal oedema response and the total oedema response (monitored as area under the time course curve). H. virginiana was inactive and G. officinale was only active at 200 mg kg-1. At 200 mg kg-1 administered before the induction of adjuvant arthritis, P. bistorta significantly inhibited both the acute and chronic phases of the adjuvant-induced rat paw swelling, while G. officinale and H. virginiana were only active against the chronic phase. Further studies on P. bistorta (100-800 mg kg-1) revealed a dose-dependent inhibition of the carrageenan-induced rat paw oedema over the dose range 100-400 mg kg-1, the E50 value being approximately 158.5 mg kg-1. The extract (200 mg kg-1), administered after the onset of the inflammatory responses reversed the course of both the carrageenan- and adjuvant-induced rat paw swelling. The results confirm that the extracts of P. bistorta, G. officinale and H. virginiana contain anti-inflammatory substances.
Asunto(s)
Antiinflamatorios no Esteroideos/uso terapéutico , Artritis Experimental/tratamiento farmacológico , Edema/tratamiento farmacológico , Extractos Vegetales/uso terapéutico , Plantas Medicinales , Animales , Carragenina/toxicidad , Edema/inducido químicamente , Inyecciones Subcutáneas , Masculino , Ratas , Ratas Sprague-Dawley , Ratas WistarRESUMEN
The anti-inflammatory activities of extracts from the resins of four species of the plant family Burseraceae, Boswellia dalzielli, Boswellia carteri (gum olibanum), Commiphora mukul, and Commiphora incisa, were studied. The aqueous extracts of the resins of B. dalzielli, C. incisa, and C. mukul significantly inhibited both the maximal edema response and the total edema response during 6 h of carrageenan-induced rat paw edema. The octanordammarane triterpenes, mansumbinone and mansumbinoic acid, isolated from the resin of C. incisa, were separated and tested. Administered prophylactically, mansumbinone proved to be more than 20 times less potent than indomethacin and prednisolone in inhibiting carrageenan-induced rat paw edema. However, the molar potency of mansumbinoic acid was within one order of magnitude of those of indomethacin and prednisolone. The anti-inflammatory action of the acid on the carrageenan-induced edema was dose-related between 1.3 x 10(-5) and 2.5 x 10(-4) mol kg-1 when given before the inflammatory stimulus. The acid was able to reverse an established carrageenan-induced inflammatory response when administered 2 h after induction. Daily administration of mansumbinoic acid at a single dose level (1.5 x 10(-4) mol kg-1) significantly reduced joint swelling in adjuvant arthritis in rats. The results indicated that this compound is worthy of further investigation as an anti-inflammatory drug.
Asunto(s)
Antiinflamatorios no Esteroideos/farmacología , Plantas Medicinales/química , Resinas de Plantas/farmacología , Animales , Antiinflamatorios no Esteroideos/aislamiento & purificación , Artritis Experimental/tratamiento farmacológico , Masculino , Ratas , Ratas Wistar , Resinas de Plantas/aislamiento & purificación , Triterpenos/aislamiento & purificación , Triterpenos/farmacologíaRESUMEN
A technique has been developed to monitor changes in synovial vascular tone and leakage of macromolecules, two of the cardinal features of inflammation. The technique permits not only quantitative sequential measurements of the leakage of 125I-albumin from the circulation into the synovium, but also semiquantitative continuous monitoring of the leakage changes. It allows simultaneous continuous monitoring of changes in synovial vascular tone as well. Vascular protein leakage was monitored semiquantitatively by measuring the radioactivity of 125I-albumin in synovial perfusate when passed through a flow cell consisting of a plastic tubing coil situated inside the well of a gamma detector. Quantitative measurements were provided by collecting and counting the synovial perfusate for 125I-albumin. Synovial vascular tone was monitored continuously by measurement of the change in joint radiation emitted by in vivo-labelled 99m-Tc erythrocytes. The in vivo labelling procedure yielded an 86% +/- 9% labelling efficiency. The degree of erythrocyte labelling was stable throughout the course of the experiment. Using this technique, the abilities of histamine to induce changes in synovial vascular tone and protein leakage were examined. Intraarticular infusion of 1 ng/mL histamine produced a 61% +/- 24% increase in synovial vascular blood volume, but did not significantly increase 125I-albumin leakage above that produced by Krebs solution alone. Higher concentrations produced a concentration-related increase in the leakage of 125I-albumin, which was not accompanied by appreciable increases in synovial vascular blood volume above the basal line. The simultaneous and continuous monitoring provided by this technique has revealed an apparent dissociation between vascular tone and vascular protein leakage in response to intraarticular histamine.
Asunto(s)
Monitoreo Fisiológico/métodos , Músculo Liso Vascular/fisiología , Membrana Sinovial/fisiología , Animales , Volumen Sanguíneo , Eritrocitos , Miembro Posterior , Masculino , Perfusión , Conejos , Albúmina Sérica Radioyodada , Pertecnetato de Sodio Tc 99mRESUMEN
OBJECTIVE: Canine coronary artery was recently reported to contain a cathepsin like acid optimum enzyme and a kallikrein like alkaline optimum enzyme which cleaved from a crude kininogen preparation a vasodilator uterus contracting substance. The aim of this study was to seek the presence of similar acid optimum enzymes in canine ventricular myocardium and in a large systemic artery, the aorta. METHODS: Aqueous canine tissue extracts were tested for the ability at different pHs to release uterus contracting substance (using rat isolated oestrous uterus) from a kininogen preparation. After gel filtration, the extracts were tested for the presence of arginine-amidase activity (substrate: D-Val.Leu.Arg.pNA) and enzymic activity forming bradykinin like immunoreactivity. Tissues were obtained from anaesthetised greyhounds which had been used in control studies and had received no other drug treatment. RESULTS: Ventricular extracts released uterus contracting substance optimally at pH 5.2-5.4, but not at alkaline pH, neither was bradykinin like immunoreactivity formed at alkaline pH. Inhibitor studies and gel filtration showed this activity to be due to a cathepsin-D-like enzyme, molecular weight (MW) 42.6 (SD 0.9) kd, which was an arginine amidase and released bradykinin like immunoreactivity from a plasma kininogen. Aortic extracts showed two pH related peaks of uterus contracting substance formation, at pH 5.2 and (unlike myocardium) at pH 8. Also unlike myocardium, aortic extracts gave two acid optimum kininogenase peaks on gel filtration, with MW 42(4.6) kd and 252(39) kd, respectively. Both peaks released bradykinin like immunoreactivity. CONCLUSIONS: Canine aorta contained an alkaline optimum and two acid optimum enzymes, while ventricle contained only a cathepsin-D-like acid optimum enzyme, all of which could form bradykinin like immunoreactivity. The ability of the ventricular enzyme to form a kinin in the slightly acid conditions of myocardial ischaemia may have a protective role.
Asunto(s)
Aorta/enzimología , Calicreínas/análisis , Miocardio/enzimología , Animales , Bradiquinina/biosíntesis , Cromatografía en Gel , Perros , Concentración de Iones de Hidrógeno , Peso Molecular , Contracción Miocárdica/efectos de los fármacosRESUMEN
A standard colitic lesion was induced in male BKA mice by intrarectal administration of butyric acid (7.5%, 0.1 ml, 10 sec contact). Animals were killed after 5 h and the 'colitic score', increase in colonic tissue water ('oedema') and colonic tissue content of myeloperoxidase (MPO, a marker for neutrophils) were determined. Drug was administered intrarectally in 0.2 ml saline 20 min before colitis induction. In colitic animals given vehicle alone, all these parameters increased (P less than 0.05) compared to the non-colitic controls. In colitic animals given 16,16-dimethyl PGE2 (0.2-20000 micrograms/kg), colitic score was reduced (P less than 0.05) at all dose levels when compared with vehicle-treated colitic animals. The oedema and MPO showed a dose-related reduction (r = -0.895 and -0.904 respectively). In mouse colon 16,16-dimethyl PGE2 showed a protective action against butyric acid-induced colitic damage.
Asunto(s)
16,16-Dimetilprostaglandina E2/uso terapéutico , Butiratos/toxicidad , Colitis/tratamiento farmacológico , Colon/efectos de los fármacos , Mucosa Intestinal/efectos de los fármacos , Animales , Ácido Butírico , Colitis/inducido químicamente , Colitis/patología , Colon/patología , Relación Dosis-Respuesta a Droga , Mucosa Intestinal/enzimología , Mucosa Intestinal/patología , Masculino , Ratones , Peroxidasa/metabolismoRESUMEN
1. The rat vas deferens releases both PGE2 and PGF2 alpha under basal conditions in vitro but the human vas deferens synthesizes prostaglandins only when arachidonic acid is supplied exogenously. 2. The release of PGE2 and PGF2 alpha is augmented by alpha-adrenoceptor activation or by BaCl2, both of which cause contraction. 3. Release of PGE2 and PGF2 alpha is substantially inhibited by indomethacin 10 micrograms ml-1 which does not affect contraction. 4. Contraction is strongly inhibited by higher concentrations of indomethacin (50-80 micrograms ml-1). 5. It is concluded that the release of PGE2 and PGF2 alpha from the rat and human vas deferens is not correlated with contraction.
Asunto(s)
Dinoprost/biosíntesis , Dinoprostona/biosíntesis , Indometacina/farmacología , Contracción Muscular/efectos de los fármacos , Conducto Deferente/efectos de los fármacos , Animales , Etanol/farmacología , Humanos , Masculino , Conejos , Ratas , Ratas Endogámicas , Especificidad de la Especie , Conducto Deferente/metabolismoRESUMEN
The presence of an acid optimum (pH 6) enzyme capable of generating a spasmogenic, vasodilator polypeptide from human plasma kininogen has been demonstrated in dog coronary arteries, veins and in the wall of the left ventricle. This enzyme also cleaved the tripeptide kallikrein substrate Val-Leu-Arg-pNA. Highest amounts were present in the coronary arteries. Gel filtration (Sephacryl S-300) of coronary artery extracts gave a peak for this acid optimum enzyme of 38, 300 +/- 800 Daltons. Its activity was inhibited by pepstatin but not by aprotinin or soya bean trypsin inhibitor. This enzyme, which is similar to a cathepsin, may play a role in the processing of peptide hormones in the heart and coronary vessels.
Asunto(s)
Vasos Coronarios/enzimología , Cininas/fisiología , Vasodilatación/fisiología , Animales , Aprotinina/farmacología , Presión Sanguínea/efectos de los fármacos , Quimotripsina/farmacología , Vasos Coronarios/efectos de los fármacos , Perros , Femenino , Concentración de Iones de Hidrógeno , Técnicas In Vitro , Cininas/metabolismo , Peso Molecular , Miocardio/enzimología , Pepstatinas/farmacología , Ratas , Inhibidores de Tripsina/farmacología , Útero/efectos de los fármacos , Vasodilatación/efectos de los fármacosRESUMEN
The presence of amidases cleaving the tripeptide VAL.LEU.ARG.pNA, and liberating from human plasma kininogen substance(s) able to contract uterine smooth muscle and to lower blood pressure (uterus contracting and hypotensive activity), has been demonstrated in vascular and muscle tissues from normally perfused and ischaemic areas of dog hearts. Studies were carried out on blood free preparations of coronary arteries and veins and normally perfused and ischaemic ventricle. All the tissues were found to contain both acid optimum (pH 6) and alkaline optimum (pH greater than 9) enzymes forming uterus contracting substance (UCS, bioassayed on isolated uterus of rats in oestrus), the highest levels of both activities being found in arterial tissues and the least in ventricle. Enzyme levels in ischaemic or normally perfused ventricle did not differ significantly. Gel filtration (Sephacryl, S-300) of coronary artery extracts gave one peak each of acid optimum enzyme with a molecular weight of 38,300 +/- 800 daltons and alkaline optimum enzyme with a molecular weight of 92,100 +/- 4000 daltons. Both acid and alkaline enzyme fractions cleaved the tripeptide substrate with pH optima identical to those for UCS formation. The acid optimum activity, both of UCS formation and tripeptide cleavage, was inhibited by pepstatin but not by aprotinin or soybean trypsin inhibitor (SBTI). The alkaline optimum activity was inhibited by aprotinin and SBTI but not pepstatin. Both acid and alkaline optimum enzymes released a hypotensive agent from a plasma protein substrate. The molecular weight and response to inhibitors of the acid optimum enzyme were similar to a cathepsin, and those of the alkaline optimum enzyme were similar to plasma kallikrein.