Effects of an inotropic agent, RO 2-2985 (X-537A), on regional blood flow and myocardial function in chronically instrumented conscious dogs and anesthetized dogs.

RO 2-2985 produced a marked positive inotropic effect in unanesthetized, chronically instrumented dogs, measured as an increase in left ventricular dP/ dt and an increase in maximum velocity of myocardial fiber shortening. Similar changes produced in dogs in hemorrhagic shock lasted for 2-3 hours. RO 2-2985 increased peripheral blood flow and caused marked increases in both coronary and renal blood flows. The drug altered the response of the renal vascular bed to subsequent norepinephrine administration. After administration of a single dose of RO 2-2985, norepinephrine produced sustained increases in renal blood flow, and this altered responsiveness to norepinephrine persisted for periods ranging from 1 to 3 weeks.