Cyclosporine-induced hypertension and decline in renal function in healthy volunteers

OBJECTIVE: To investigate the effect of cyclosporine A (CsA; Sandimmun Neoral) on systemic and renal hemodynamics, tubular function, and sodium excretion in healthy volunteers. Furthermore, we studied whether CsA enhances the systemic and renal hemodynamic sensitivity to norepinephrine. METHODS: Eighteen healthy volunteers were administered 10 mg/kg CsA or placebo capsules in a double-blind fashion. The mean arterial blood pressure (MAP), renal vascular resistance (RVR), glomerular filtration rate (GFR), and renal clearances of lithium (CLi) and sodium (CNa) were measured for 8 h after ingestion of the capsules. Norepinephrine (2 microg/kg per h) was infused intravenously for 1.5 h into nine subjects. RESULTS: CsA increased the MAP by 17+/-2 mmHg. The GFR decreased by 18+/-2% (P < 0.001) and the RVR increased by 37+/-4% (P< 0.001) after ingestion of CsA. The CsA-induced increase in MAP preceded the CsA-induced fall in GFR. The rise in MAP was followed by an early 35+/-8/0 increase in CNa (P < 0.001). At the end of the 8 h study period, CNa decreased by 25+/-7% (P < 0.001). Using CLi, it was found that the initial natriuresis had been caused by a relative decrease both in proximal and in distal tubular reabsorption of sodium, whereas the late sodium retention was secondary to the CsA-induced fall in GFR. Infusion of norepinephrine increased the MAP, RVR, and filtration fraction, and decreased the renal plasma flow, without CsA having any additional effect. CONCLUSION: It was demonstrated that a single oral dose of CsA caused a rise in blood pressure and transient natriuresis, followed by a fall in GFR and antinatriuresis. Thus, the present study confirms and extends earlier observations that renal dysfunction and sodium retention are not the initiating events in CsA-induced hypertension. The study also affords evidence suggesting that such rises in blood pressure are not mediated by an increased sensitivity to norepinephrine.