Hemodynamic responses to dopamine infusion at controlled normal and low cardiac output states in the anesthetized dog

In order to isolate the renal and pulmonary vascular effects of dopamine, we employed a dog preparation utilizing fixed venous return in order to control cardiac output at either a normal or low flow state. Dopamine infusion was carried out at doses of 8 and 16 microng/Kg./min. Heart rate, mean systemic arterial pressure, mean pulmonary artery pressure, and renal blood flow were measured. Changes in mean systemic arterial pressure, mean pulmonary artery pressure, and renal blood flow were not significant at either doses of dopamine. There was a dose-related increase in heart rate, most significant with a dose of 16 microng/Kg./min. and low cardiac output. No evidence was found to substantiate the existence of a specific dopaminergic receptor in the renal vasculature when cardiac output was controlled.