THE IMPROVEMENT of vital-organ perfusion is an accepted aim in shock therapy. The most effective approach to this aim is controversial. Adequate blood volume repletion does not necessarily result in an optimal regional distribution of blood flow. The present study was designed to compare the effects of two drugs, levarterenol and isoproterenol, on cardiac output and blood flow to the superior mesenteric and renal vascular beds. Though chemically related, these drugs have divergent effects upon the resistance vessels, levarterenol being a vasoconstrictor and isoproterenol a vasodilator.
Levarterenol was an obvious choice for a vasopressor drug because of its wide clinical usage, its role as an endogenous sympathetic mediator,1 and because of the inconsistency of reported results following its application in experimental and clinical shock. The use of levarterenol to elevate pressure has produced both positive and negative experimental results in terms of survival and measured blood flow data. Reports