Dopamine and the kidney.

It would seem established beyond peradventure that dopamine is formed in the kidney from circulating L-dopa. The likely site would appear to be the renal tubular cells but the contribution of the renal dopaminergic nerves needs further evaluation. Moreover it is probably that dopamine formed within the kidney acts there on specific receptors. This results in vasodilatation of renal blood vessels, by action on vascular receptors, and natriuresis, by an effect on tubular sodium transport mechanisms. Dopamine may form an integral part of the renal natriuretic cascade by, in its turn, evoking both the kallikrein-bradykinin system and the production of renal prostaglandins. Specific activation of the renal dopaminergic system by the administration of suitable agonists or renal prodrugs may prove possible in the future. Abnormalities in the renal production of dopamine may be important in several hypertensive and oedematous disorders. Further work will be required to establish a possible role for dopamine in these conditions and to determine whether they will benefit from treatment with suitable dopamine agonists. Dopamine, once regarded as of little importance outside the central nervous system, has certainly come to occupy a central place in renal salt handling. The ratio of dopamine production in the kidney to that for renin may be of pivotal importance in the control of systemic arterial pressure.