INHIBITION OF SYMPATHOMIMETIC EFFECTS ON THE HEART

Abstract

The adrenaline beta-receptor blocking drug, pronethalol, and the sympathomimetic amines, (-)-ephedrine, (-)-amphetamine, dexamphetamine, (-)-Psi-ephedrine and tyramine, inhibited the sympathomimetic effects of butyrylcholine and tyramine on the guinea-pig isolated atrium. Being reversible and noncompetitive, this antagonism was unspecific and not due to blockade of adrenaline receptors, although pronethalol inhibited the effect of noradrenaline competitively.