Effect of nifedipine on the renal functional reserve in cyclosporine-treated renal-transplant recipients

Cyclosporine-a-based immunosuppression and renal functional reserve in organ-transplant patients

The glomerular filtration rate (GFR) may increase after oral protein overload or after an amino acid infusion. Renal functional reserve (RFR) is defined as the difference between the poststimulation and the baseline glomerular filtration rate. RFR has been studied in transplant patients. The results have been conflicting because RFR may be affected by donor age, the time from transplantation, the type of immunosuppression, the basal GFR, the body surface area, and the presence of calcium channel blocker therapy. We observed that during the first year posttransplantation renal recipients maintained on cyclosporine (CsA) therapy retain a level of RFR that represents approximately 30% of the baseline GFR. Moreover, hypertensive cyclosporine treated renal transplant patients on calcium channel blocker therapy do not exhibit permanent glomerular hyperfiltration until 8 months posttransplantation. Finally, both renal and heart transplant patients on cyclosporine therapy possess renal reserve, but the single renal graft in renal transplant patients shows a proportionally higher baseline GFR and a better ability to exhibit a RFR than the two native kidneys in heart transplant patients. Many studies, although not all, have documented a positive RFR in both children and adult cyclosporine-treated kidney graft recipients, demonstrating that hyperfiltration is not the rule following single kidney transplantation.

Functional glomerular reserve in recipients of en bloc pediatric transplant kidneys

BACKGROUND

The transplantation of an adequate renal mass is increasingly recognized to be of importance. The improved graft survival is probably due to a lesser risk of developing hyperfiltration-associated lesions.

METHODS

We have reviewed the glomerular reserve in our recipients of en bloc pediatric transplant kidneys after an intravenous amino acid overload and compared them to single adult kidney transplant recipients.

RESULTS

En bloc transplants evidenced increased glomerular filtration rate as compared with baseline as from the second hour of amino acid infusion (from 71+/-14 to 84.9+/-17 ml/min, 1.73 m2, P<0.05) and increased renal plasma flow as from the third hour (from 335+/-116 to 402+/-155 ml/min, 1.73 m2, P<0.05). In the single adult kidney recipient group, no change was seen either in the glomerular filtration rate (from 62.5+/-13 to 58.1+/-13 ml/min, 1.73 m2, P=NS) nor in renal plasma flow (from 354+/-125 to 304+/-98 ml/min, 1.73 m2, P=NS).

CONCLUSIONS

These results show that patients receiving en bloc pediatric kidney transplantations have a greater renal functional reserve and show a lesser risk of hyperfiltration.