[Low-dose dopamine as an activator of renal catecholamine receptors of different classes. I. Studies in water-salt depletion].

The renal function in healthy man with salt and water depletion induced by natriuretic treatment was explored during steady hypotonic polyuria. Four 15 min clearance (cl.) periods, before, during and after dopamine (DA) infusion in a subpressor dose were performed. The 12 examined subjects showed different renal hemodynamic responses in the early stage of DA infusion, i.e. hyperemic (4 subjects, subgroup A) or ischemic (8 subjects, subgroup B). A decrease in urinary sodium excretion and increase in tubular sodium reabsorption, in particular at the diluting segment level, were induced by DA in both subgroups, at least in the late stage of infusion. During the control cl. period in subgroup A as compared with B the renal plasma flow was lower and the tubular sodium reabsorption higher, suggesting a relatively higher level of renal adrenergic activity.