RESUMO
We studied the effect of α2-adrenoreceptor antagonist yohimbine in concentrations of 10-9-10-6 M on the inotropy, chronotropy, and coronary flow of the Langendorff-isolated rat heart. It was found that antagonist of α2-adrenoreceptors yohimbine changes all the studied parameters of the isolated heart. The force of left ventricular myocardial contraction, HR, and coronary flow decreased after application of all concentrations of α2-adrenoreceptor antagonist. The maximum inotropic, chronotropic, and vascular effects were observed when the antagonist was applied to the perfused solution in a concentration of 10-9 M. The minimum decrease in coronary flow and HR was observed when yohimbine was applied in a concentration of 10-8 M; minimum effect on myocardial contractility was revealed at α2-adrenoreceptor blocker concentration of 10-7 M.
