Alpha-adrenoceptor-mediated positive inotropic effect of phenylephrine in isolated human ventricular myocardium.
In isolated human ventricular myocardium the alpha-adrenoceptor agonist phenylephrine had a positive inotropic effect in preparations from 9 of 14 patients. This effect was seen in the presence of the beta-adrenoceptor-blocking agent propranolol but was nearly abolished by the alpha-adrenoceptor blocking agent prazosin. In contrast to the beta-adrenoceptor-mediated positive inotropic effect, the effect of phenylephrine was accompanied by a prolongation of the isometric contraction. The results suggest that alpha-adrenoceptors exist in human ventricular myocardium.
D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D008875:Middle Aged; D009200:Myocardial Contraction / Q000187:drug effects*; D010656:Phenylephrine / Q000494:pharmacology*; D011224:Prazosin / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology; D011942:Receptors, Adrenergic, alpha / Q000187:drug effects*
D011942:Receptors, Adrenergic, alpha; D010656:Phenylephrine; D011433:Propranolol; D007545:Isoproterenol; D011224:Prazosin