Comparative actions of pentobarbital and verapamil on canine cerebral and peripheral arteries in vitro

Verapamil and pentobarbital were compared for their actions on isolated canine cerebral (basilar and middle cerebral) and peripheral (mesenteric) arteries of similar diameter. The two agents shared several nonselective actions on canine arteries, but differed widely in potency. Both agents produced direct relaxation of cerebral, but not peripheral, arteries, and both agents inhibited constriction of cerebral and peripheral arteries by KCl and CaCl2 (in K+-depolarizing, Ca2+-deficient media). However, 1 mM pentobarbital was required to produce the same maximal effects as 4 uM verapamil. In addition, verapamil selectively blocked constriction of cerebral arteries by a receptor-mediated agent, prostaglandin F2a, while pentobarbital was nonselective in its blockade. On the basis of their comparative actions on isolated cerebral and peripheral arteries, calcium channel blockers such as verapamil may be a more rational choice in the treatment of cerebral ischemia than the barbiturates.