RENAL FUNCTIONAL RESERVE IN CALCIUM-CHANNEL BLOCKER-TREATED HYPERTENSIVE RECIPIENTS OF KIDNEY-TRANSPLANT

Renal functional reserve during infusion of an amino acid solution was examined in 12 cyclosporin-treated kidney recipients at 1 (T1) and 8 months (T2) after transplantation. Patients were retrospectively divided into six normotensive (NT) and six hypertensive recipients (HT) maintained on monotherapy with a calcium channel blocker. Baseline glomerular filtration rates (GFR) were similar in NT and HT at T1 and T2. Renal functional reserve was identical in NT and HT at T1 (15+/-7 vs 18+/-13 ml/min/1.73 m(2)) but significantly greater in HT at T2 (11+/-5 vs 23 +/-10 ml/min/1.73 m(2) P<0.05). At T2, baseline proximal tubule outflow (lithium clearance) was greater in HT (26+/-8 vs 16+/-3 ml/min/1.73 m(2): P<0.05), whereas fractional proximal reabsorption was less (54+/-11% vs 67+/-5%; P<0.05). These results indicate that: (i) hypertensive recipients on calcium channel blocker therapy do not exhibit permanent glomerular hyperfiltration until 8 months after transplantation, and have a reduced proximal reabsorption; (ii) measurement of amino acid-stimulated GFR and renal functional reserve is a more sensitive method than that of baseline GFR for evaluating renal function and the effects of therapy in kidney recipients.