Up to now, no studies have been performed in normal humans to investigate the role of renal hemodynamic abnormalities in relation to acute-cyclosporin A (CsA) renal dysfunction and to verify whether the specific renal vasodilator, dopamine, can counteract these abnormalities. Eight normal subjects were examined both (A) after oral CsA (12 mg/kg body wt) and (B) after oral CsA + dopamine infusion (2 mg/kg body wt/min), under water diuresis. Both in protocols A and in B, four basal renal clearances were performed before CsA and every twenty minutes for four hours after CsA administration. In protocol A, after CsA, inulin (GFR) and PAH clearance (RPF) fell by up to 27% and to 41%, respectively, so that filtration fraction (FF) increased (P less than 0.01). A slight (not significant) hypertension occurred while renal resistances were markedly raised (P less than 0.001). Fractional urine and Na+ excretion as well as CH2O decreased, while UOsm increased (P less than 0.01). In protocol B, dopamine was infused from 120 to 180 minutes after CsA (that is, when the maximal adverse effects of CsA on renal hemodynamics had been observed in A). Dopamine infusion could reverse completely the effects of CsA on RPF, GFR, fractional urine output and CH2O; only UOsm remained higher than normal in conclusion with an increased fractional excretion of sodium (P less than 0.01). No changes were observed in plasma renin activity, aldosterone and in urinary epinephrine and norepinephrine excretion both in protocols.
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