COMPARISON OF EFFECTS OF DOPAMINE HYDROCHLORIDE AND DOPEXAMINE HYDROCHLORIDE ON ABDOMINAL AND FEMORAL HEMODYNAMICS IN ANESTHETIZED DOGS

The effects of dopamine and dopexamine administered in graded intraven ous bolus injections (0.1-51.2 mug . kg-1) were compared in the renal and femoral, and in a number of splanchnic vessels at the organ level simultaneously in anesthetized dogs. Hemodynamic data are presented fo r each artery as conductance, which was obtained by dividing mean flow by mean arterial pressure. The data were analyzed in two different wa ys: 1) by responses at intervals of 3 sec to 12.8 mug dopamine or dope xamine during 1 min, and 2) by dose-response curves. Additionally, uri ne volume was measured during dopamine and dopexamine administration. During a period of 1 min after an injection of dopamine, early and lat e effects could be distinguished, while heart rate was unaltered. In t he superior mesenteric, inferior mesenteric, splenic, common hepatic, renal, and femoral arteries, an early (at 18-21 sec) reduction in cond uctance was seen. The early reduction was often followed by an increas e above the preinjection level. After dopexamine, the early reduction in conductance was not seen, except in the left gastric artery. In con trast to the effect of dopamine, dopexamine induced a more pronounced increase during the late phase. Contrary to dopamine, dopexamine incre ased the conductance in the common hepatic artery bed. It remains ques tionable whether dopaminergic receptors are present in this vascular b ed. Dopamine raised blood pressure and urine production dose-dependent ly. Dopexamine decreased aortic pressure. Low dosages of dopexamine in creased urine production, without raising renal blood flow. An advanta ge of dopexamine over dopamine could be that dopexamine does not stimu late alpha-adrenergic receptors. (C) 1993 Wiley-Liss, Inc.