The pharmacological basis of coronary and systemic vasodilator actions of diazepam (Valium)

Abstract

1 The effects of α and β-adrenoceptor blockade, depletion of catecholamine stores, vagotomy, atropine, and ganglionic blockade on diazepam-induced vasodilatation were investigated in forty-six anaesthetized dogs. 2 Coronary blood flow was measured by timed collections of coronary venous efflux from fibrillating, decompressed ventricles; coronary and systemic vascular resistances were determined during total cardiopulmonary bypass under conditions of normothermia and constant aortic (coronary artery) pressure. 3 No significant alteration in the vasodilatation produced by diazepam was observed following either vagotomy or α-adrenoceptor blockade; partial inhibition of vasodilatation occurred after β-adrenoceptor blockade or catecholamine depletion, and nearly total inhibition was observed after small doses of atropine or ganglion-blocking agents. 4 The results suggest that diazepam may act as a specific ganglion-stimulant, causing active sympathetic and cholinergic vasodilatation.