CARDIAC AND PERIPHERAL EFFECTS OF DOPAMINE INFUSION IN ENDOTOXIN SHOCK IN THE DOG

¹ Veterans Administration Hospital and Departments of Physiology, Medicine and Surgery, University of Oklahoma Medical Center, Oklahoma City, Oklahoma

The present investigation was designed to evaluate the cardiovascular effects of dopamine (3,4-dihydroxyphenylethylamine) in dogs administered endotoxin. In order to separate peripheral from cardiac effects, a venous return preparation was used, in which cardiac inflow was held constant. Intra-atrial infusion rates of dopamine between 17 and 34 µg/kg/min caused increases in venous return and mean systemic arterial pressure. Dopamine markedly prevented pooling after an LD80 of endotoxin until infusion was stopped. Ten minutes after cessation of dopamine infusion, pooling rates were not significantly different from those of the untreated, shocked animals. Dopamine infusion begun 10 minutes after endotoxin injection resulted in tachycardia and decreased left atrial pressure in the presence of a steady cardiac input and relatively constant systemic vascular resistance. Right atrial pressure and pulmonary vascular resistance were maintained above pre-endotoxin values during dopamine infusion, while portal vein pressure fell and venous return progressively increased. Results from survival studies in correlation with the above findings suggest beneficial actions of dopamine on both the left ventricle and peripheral vasculature in maintaining an adequate circulating blood volume.