[Calcium-antagonism, a new principle in coronary vasodilation].
As in all other vessels, coronary contractile tone depends on the availability of Ca ions. Thus, Ca-antagonistic drugs such as verapamil, prenylamine or nifedipine produce a loss of muscle tone in depolarized coronary strips. One molecule of these compounds successfully blocks the action of thousands of Ca ions in excitation-contraction coupling. Nitroglycerine and other nitrites exert a similar action, though in their case relaxation is more rapid, incomplete and spontaneously reversible. In analogy to their well-known Ca-synergistic action on heart muscle fibres, cardiac glycosides are also capable of increasing the coronary vascular tone even in very low concentrations. If, however, suitable doses of Ca-antagonistic compounds are simultaneously administered, the hearts are protected against this unpleasant coronary side effect without an appreciable loss of the inotropic glycoside action on the myocardium.
D000818:Animals; D002110:Caffeine / Q000494:pharmacology; D002118:Calcium / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D002301:Cardiac Glycosides / Q000494:pharmacology; D002866:Chromonar / Q000494:pharmacology; D003331:Coronary Vessels / Q000187:drug effects*; D009129:Muscle Tonus / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects; D009543:Nifedipine / Q000494:pharmacology; D009573:Nitrites / Q000494:pharmacology; D005996:Nitroglycerin / Q000494:pharmacology; D010208:Papaverine / Q000494:pharmacology; D011299:Prenylamine / Q000494:pharmacology; D013552:Swine; D014665:Vasodilator Agents; D014700:Verapamil / Q000494:pharmacology*
D002301:Cardiac Glycosides; D009573:Nitrites; D014665:Vasodilator Agents; D002110:Caffeine; D014700:Verapamil; D010208:Papaverine; D005996:Nitroglycerin; D009543:Nifedipine; D011299:Prenylamine; D002866:Chromonar; D002118:Calcium
Ca-antagonismo, un nuovo principio nella vasodilatazione coronarica