Inhibition by Cd2+ verapamil and papaverine of Ca2+-induced contractions in isolated cerebral and peripheral arteries of the dog.
1 In helically cut strips of canine cerebral arteries exposed to Ca2+-free media and depolarized by K+, the addition of Ca2+ caused biphasic (transient and sustained) contractions, while in coronary and mesenteric arteries, the additon of Ca2+ produced a sustained contraction sometimes preceded by a slight transient contraction. 2. These Ca2+-induced contractions were attenuated by Cd2+ (50 to 100 micron) in a dose-dependent manner, the attenuation being greater in cerebral than in coronary and mesenteric arteries. The inhibitory effect of Cd2+ was prevented and partially reversed by 1 mM cysteine. 3. Verapamil and papaverine were also effective in attenuating the Ca2+-induced contrations in cerebral and peripheral arteries: susceptibility to verapamil was in the order, cerebral greater than coronary greater than mesenteric, while that to papaverine was in the order, cerebral=coronary greater than mesenteric. 4. It may be concluded that the agents that interfere with trans-membrane influxes of Ca2+ cause a greater relaxation in cerebral than in peripheral arteries, as is seen with papaverine, a non-specific vasodilator.
D000818:Animals; D001808:Blood Vessels / Q000187:drug effects*; D002104:Cadmium / Q000494:pharmacology*; D002118:Calcium / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D002536:Cerebral Arteries / Q000187:drug effects; D003331:Coronary Vessels / Q000187:drug effects; D004285:Dogs; D005260:Female; D066298:In Vitro Techniques; D008297:Male; D008638:Mesenteric Arteries / Q000187:drug effects; D009119:Muscle Contraction / Q000187:drug effects*; D009130:Muscle, Smooth / Q000187:drug effects*; D010208:Papaverine / Q000494:pharmacology*; D014700:Verapamil / Q000494:pharmacology*
D002104:Cadmium; D014700:Verapamil; D010208:Papaverine; D002118:Calcium