title: Calcium antagonistic action involved in vasodilation by brovincamine.
abstract: Possible mode of vasodilative action of brovincamine was assessed in isolated cardiovascular preparations in comparison with verapamil and papaverine. Brovincamine (IC50: 1.2 x 10(-5) M), verapamil (IC50: 3.5 x 10(-7) M) or papaverine (IC50: 2.5 x 10(-5) M) caused a dose-dependent relaxation of potassium (30 mM)-contracture in the rabbit pulmonary arterial segment. This relaxation by verapamil or brovincamine, but not by papaverine, was antagonized by increasing external Ca2+ concentration to 12.4mM. Duration of slow action potentials of partially depolarized guinea-pig papillary muscle was reduced by 14 min exposure to brovincamine (5 x 10(-5) M) or verapamil (10(-5) M. These results suggest that brovincamine produces a vasodilation via a slow Ca2+-channel blockade.
mesh_terms: D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D002121:Calcium Channel Blockers; D006168:Guinea Pigs; D066298:In Vitro Techniques; D008297:Male; D010208:Papaverine / Q000494:pharmacology; D010210:Papillary Muscles / Q000502:physiology*; D011188:Potassium / Q000494:pharmacology; D011651:Pulmonary Artery / Q000502:physiology*; D011817:Rabbits; D014661:Vasoconstriction / Q000187:drug effects; D014664:Vasodilation / Q000187:drug effects*; D014700:Verapamil / Q000494:pharmacology; D014748:Vinca Alkaloids / Q000494:pharmacology*; D014749:Vincamine / Q000031:analogs & derivatives / Q000494:pharmacology*
chemical_list: D002121:Calcium Channel Blockers; D014748:Vinca Alkaloids; D014749:Vincamine; C033581:11-bromovincamine; D014700:Verapamil; D010208:Papaverine; D011188:Potassium