The actions of dopamine and of sulpiride on regional blood flows in the rat kidney.

Abstract

Blood flow was measured in the renal cortex and medulla of anesthetized rats by the H washout method. The effects of dopamine infusion were measured. Low doses of dopamine (20 and 65 nmol .cntdot. kg .cntdot. min) caused only small increases in renal blood flow, and a higher dose (200 nmol .cntdot. kg .cntdot. min) caused vasoconstriction. After .alpha.-blockade with phenoxybenzamine (9 .mu.mol/kg), all doses of dopamine caused vasodilatation in the cortex and medulla of the kidney. This dopamine-induced renal vasodilatation was abolished by sulpiride (0.7 .mu.mol/kg per min), but was only slightly attenuated by propranolol (10 .mu.mol/kg). Sulpiride did not significantly alter the renal blood flow responses to noradrenaline [norepinephrine, NA] or isoprenaline, or the blood pressure responses to histamine, acetylcholine, 5HT [serotonin], NA and isoprenaline. In normal rats, infusion of sulpiride generally caused a reduction in renal cortical blood flow. This response showed a positive correlation with the initial blood pressure. There may be specific dopamine receptors in the renal vasculature of the rat, and dopamine may play a role in the normal control of renal blood flow.