TY - JOUR T1 - INFLUENCE OF ANGIOTENSIN ON THE EFFECTS OF TYRAMINE UPON THE CONTRACTILE FORCE OF ISOLATED RABBIT ATRIA JF - Journal of Pharmacology and Experimental Therapeutics JO - J Pharmacol Exp Ther SP - 487 LP - 493 VL - 158 IS - 3 AU - A. Illanes AU - J. Pérez-Olea AU - M. Quevedo AU - A. Ortiz AU - M. Lazo Y1 - 1967/12/01 UR - http://jpet.aspetjournals.org/content/158/3/487.abstract N2 - It has been suggested previously that angiotensin increases the cardiovascular effects of some sympathomimetic amines. The present paper deals with the influence of angiotensin on the actions of tyramine and norepinephrine on isolated heart preparations. In spontaneously beating and electrically driven isolated rabbit atria, set up in a bath with Krebs' solution, the exposure to 0.007 µg/ml of angiotensin II augmented the positive inotropic effect of tyramine. The chronotropic effect of tyramine on the spontaneously beating atria was unaltered by angiotensin. Angiotensin in the same concentration did not modify the inotropic and chronotropic effects of norepinephrine. In norepinephrine-depleted atria, tyramine lost its inotropic effect, which was partially recovered by incubating the atria with angiotensin. The possibility is advanced that tyramine could act on myocardial contraction by displacing angiotensin from inactive binding sites. © 1967 by The Williams & Wilkins Company ER -