State-dependent modulation of sympathetic firing by α1-adrenoceptors requires constitutive PKC activity in the neonatal rat spinal cord

Blockade of α2-Adrenergic Receptors Inhibits Functional Parameters of Langendorff-Isolated Rat Heart

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.