The effect of nifedipine on graft function in renal allograft recipients treated with cyclosporin A.

The effect of the calcium channel antagonist nifedipine on renal allograft function was assessed in two groups of renal transplant recipients at least one year after transplantation. Group 1 comprised 10 patients receiving low-dose prednisolone and cyclosporin A, and Group 2 comprised 9 patients receiving low-dose prednisolone and azathioprine. Before commencing nifedipine, creatinine and sodium clearance rates and the fractional excretion of sodium were similar in both two groups. Lithium clearance rates and the fractional excretion of lithium were, however, significantly lower (p less than 0.01) in Group 1 than in Group 2. The absolute reabsorption of sodium from the distal nephron (p less than 0.01), the absolute reabsorption of water from the distal nephron segment (p less than 0.01) and the fractional reabsorption of sodium from the distal tubule relative to the delivery of sodium from the proximal tubule (p less than 0.05) were also lower in Group 1. After seven days of nifedipine treatment (10 mg/8 h) there was a significant fall in sodium clearance (p less than 0.01) and fractional sodium excretion (p less than 0.05), and an increase in the fractional distal reabsorption of sodium relative to the delivery of sodium from the proximal tubule (p less than 0.01), and the fractional distal reabsorption of water relative to the delivery of water from the proximal tubule (p less than 0.02), in Group 1 but not Group 2. The only alterations observed in Group 2 were an increase in fractional lithium excretion (p less than 0.05), and a significant fall in the absolute proximal tubular reabsorption of iso-osmotic fluids (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)