Coronary vascular actions of the converting enzyme inhibitor, enalapril.
Enalapril, a potent angiotensin converting enzyme inhibitor, effectively blocked the constrictor actions of angiotensin I in isolated perfused cat coronary arteries. Enalapril, at concentrations of 25 to 100 micrograms/ml, inhibited angiotensin I by 65 to 80%. Moreover, enalapril at 100 to 200 micrograms/ml, markedly antagonized the coronary vasoconstrictor effects of angiotensin II. At 150 micrograms/ml, enalapril blocked the angiotensin II response by 80 +/- 5%, and at 200 micrograms/ml, it was blocked by 95 +/- 4%. Enalaprilic acid at 0.5 to 1.0 microgram/ml also blocked the angiotensin II response by 94 +/- 5%. Captopril, up to 250 micrograms/ml, failed to significantly antagonize angiotensin II, although it readily blocked angiotensin I in this preparation. The duration of this angiotensin II blockade lasted about 60-90 min. This angiotensin II antagonism may help explain the beneficial effects of enalapril in situations such as acute myocardial ischemia.
D000803:Angiotensin I / Q000037:antagonists & inhibitors; D000804:Angiotensin II / Q000037:antagonists & inhibitors; D000806:Angiotensin-Converting Enzyme Inhibitors; D000818:Animals; D001158:Arteries; D002216:Captopril / Q000494:pharmacology; D002415:Cats; D003331:Coronary Vessels / Q000502:physiology*; D004151:Dipeptides / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004656:Enalapril; D066298:In Vitro Techniques; D007700:Kinetics; D014661:Vasoconstriction / Q000187:drug effects*
D000806:Angiotensin-Converting Enzyme Inhibitors; D004151:Dipeptides; D000804:Angiotensin II; D004656:Enalapril; D000803:Angiotensin I; D002216:Captopril