Presynaptic dopamine receptors as mediators of dopamine-induced inhibition of neurogenic vasoconstriction.

I.v. infusion of dopamine (10 microgram/kg/min) caused significant attenuation of renal vasoconstrictor responses to sympathetic nerve stimulation in pentobarbital-anesthetized dogs, whereas renal vasoconstrictor responses to exogenously administered norepinephrine were unaffected. Desipramine treatment significantly potentiated the inhibitory effect of dopamine on neurogenic vasoconstriction. Pretreatment with pimozide, a dopamine receptor blocking agent, prevented the inhibitory influence of dopamine on renal sympathetic nerve function. These results demonstrate that dopamine can inhibit neurogenic vasoconstriction by activating presynaptic dopamine receptors present on renal sympathetic nerves.