Stimulation by phenylephrine of myocardial alpha-adrenoceptors in the left ventricle of the cat.
In the anesthetized cat phenylephrine in doses of 10(-8), 3 x 10(-8) and 10(-7) moles/kg caused an increase of dp/dt(max.) of the left ventricle without altering the heart rate. This cardiostimulating effect was inhibited by the alpha-adrenolytic drug phentolamine (10(-6) moles/kg). The beta-adrenolytic agent prindolol (10(-7) moles/kg), which inhibited the increase of dp/dt(max) evoked by isoprenaline as well as by noradrenaline did not influence the positive inotropic effect of phenylephrine, thus favouring the view that there exist myocardial alpha-adrenoceptors in the ventricle of the cat.
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002415:Cats; D005260:Female; D006321:Heart / Q000187:drug effects*; D006339:Heart Rate / Q000187:drug effects; D006352:Heart Ventricles; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D009200:Myocardial Contraction / Q000187:drug effects; D010646:Phentolamine / Q000494:pharmacology; D010656:Phenylephrine / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D010869:Pindolol / Q000494:pharmacology; D011941:Receptors, Adrenergic / Q000187:drug effects*; D012018:Reflex / Q000187:drug effects; D013268:Stimulation, Chemical
D011941:Receptors, Adrenergic; D010656:Phenylephrine; D010869:Pindolol; D007545:Isoproterenol; D010646:Phentolamine