Selective Blockade of α2-Adrenoceptor Subtypes Modulates Contractility of Rat Myocardium

Abstract

The study examined the dose-dependent effects of selective antagonists of α_2A/D-, α_2B-, and α_2C- adrenoceptors applied in concentrations of 10^—9-10^—5 M on atrial and ventricular contractility of rat myocardium in vitro. Selective blockade of each α₂-adrenoceptor subtype affected the contractile force of the atrial and ventricular strips. Various concentrations of α_2A/D- and α_2C-adrenoceptor antagonists produced positive inotropic effect on ventricular strips and negative effect on atrial strips. α_2B-Adrenoceptor blocker in the majority of the tested concentrations produced a positive inotropic effect in both atria and ventricles.