Vasodilator Action of Guanethidine

Abstract

The cardiovascular effects of intravenous guanethidine were measured in animals treated with reserpine. The action of intraarterial guanethidine was studied also in perfused forelegs of dogs. The following conclusions were reached: 1. There was no significant increase in cardiac output, heart rate, or systemic arterial pressure following intravenous guanethidine in treated animals; only sustained vasodilatation was observed. 2. The vasodilatation was caused by a local action of the drug on vascular smooth muscle. The dilatation became more pronounced following depletion of catecholamines with reserpine and repeated administration of guanethidine. 3. The dilatation did not appear to be mediated through the release of catecholamines, histamine, or acetylcholine. It may have resulted, at least in part, from stimulation of beta adrenergic receptors or other "dilator receptors" which are blocked by dichloroisoproterenol.