Changes in regional blood flows induced by dopamine and by isoproterenol during experimental hemorrhagic shock

Abstract

Although there is little experimental evidence that the heart is functionally deranged early in hemorrhagic shock, it appeared possible that desirable hemodynamic responses could be obtained with agents which would increase cardiac output without further compromising the peripheral circulation. Dopamine and isoproterenol exert a prominent positive inotropic effect on the heart. The amines differ in their action on peripheral blood vessels: isoproterenol produces β-adrenergic vasodilatation; dopamine lacks this action but does produce selective renal vasodilatation. In the experiments reported here, the hemodynamic response to intravenous infusion of these amines was examined in dogs subjected to hemorrhagic shock. In the doses selected (0.06 μg/kg per minute of isoproterenol and 6.0 μg/kg per minute of dopamine) both agents increased thoracic and abdominal aortic blood flow. "Splanchnic" and renal blood flows were increased by both amines, although the increments were statistically significant only in the case of dopamine. The cardiac output, as measured by the Fick principle, was increased only by isoproterenol.