[Sulpiride (stereoisomers, racemic) and dopamine: actions and interactions on tubular reabsorption].

In DOCA-pretreated men during hypotonic polyuria Dopamine (DA) infusion in a subpressor dosage (0.1 microgram X kg -1 X min -1) produces renal hyperemia, inhibition of isosmotic sodium reabsorption, increase in sodium distal load (s. d.l.) and finally inhibition of anisosmotic sodium reabsorption as a percentage of s.d.l. Such DA effects are variously modified by sulpiride isomers. Sodium distal load increase is still apparent in the presence of racemic, but not in the presence of either d- or l-Sulpiride isomers. However DA inhibition of anisosmotic sodium reabsorption % s.d.l. is unaffected by either or both Sulpiride isomers. If the DA tubular inhibition was dependent on specific DA receptors these receptors, unlike vascular DA receptors, would bind in a weaker way both d- and l-Sulpiride isomers.