[influence of Ca channel blockers on the positive inotropic effect of ionophore A23187 in the myocardium].
Calcium ionophore A23187 (10(-5) M) increases the force of contraction of the frog atrium up to 27 + 4.8%. The calcium antagonists d-600 (5 X 10- M), Zn2+ (2 X 10(-5) M), Mn2+ (2 X 10(-4) M) decrease the force of contraction 50, 10 and 20%, respectively, and inhibit the positive inotropic effect of ionophore A23187. Inhibition of the ionophore effect by the blockers is determined by the ability of D-600, Zn2+ and Mn2+ to form complexes with the ionophore. Besides, the affinity of these blockers to the ionophore is higher than that of Ca2+. It is assumed that Zn2+, Mn2+ and D-600 possess higher affinity to ionophore A23187 as compared with myocardial Ca-channels. Fenigidin interacts with Ca-channels to a larger degree than with ionophore A23187.
D000818:Animals; D000001:Calcimycin / Q000494:pharmacology*; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D005711:Gallopamil / Q000494:pharmacology; D066298:In Vitro Techniques; D008345:Manganese / Q000494:pharmacology; D009200:Myocardial Contraction / Q000187:drug effects*; D009543:Nifedipine / Q000494:pharmacology; D011895:Rana ridibunda; D013268:Stimulation, Chemical; D015032:Zinc / Q000494:pharmacology
D002121:Calcium Channel Blockers; D000001:Calcimycin; D005711:Gallopamil; D008345:Manganese; D009543:Nifedipine; D015032:Zinc
Vliianie blokatorov Ca-kanala na polozhitel'nyĭ inotropnyĭ éffekt ionofora A23187 v miokarde.