Acute cyclosporine-induced nephrotoxicity in renal transplant recipients: the role of the transplanted kidney.

Abstract

Cyclosporine A causes an acute reduction in GFR. The interindividual variable reduction in GFR is most likely the result of arteriolar vasoconstriction. Vasoconstriction is attributable either to a local effect of cyclosporine on renal blood vessels (intrinsic mechanism) or to a systemic effect of cyclosporine on circulating and/or neuronal factors (extrinsic mechanism). The aim of the investigation presented here was to establish whether intrinsic or extrinsic mechanisms account for the interindividual differences in the susceptibility to acute cyclosporine-induced nephrotoxicity. For that purpose, this study took advantage of the clinical transplant situation in which two (intrinsically identical) kidneys from a cadaveric donor are transplanted into two (extrinsically) different subjects. The preexisting regular daily cyclosporine doses were raised by 25% for 2 wk and by 50% for another 2 wk in 16 patients with stable renal graft function, representing eight pairs of patients, each of whom had received kidneys from the same donor. In these patients, a mean (+/- SD) maximum cyclosporine-induced increase in serum creatinine concentration of 13 +/- 11% (P < 0.001) and in serum BUN of 27 +/- 33% (P < 0.01), together with a decline in the fractional uric acid excretion of 51 +/- 89% (P < 0.02) were observed. The percentage change in serum creatinine concentrations after increased dosing of cyclosporine paralleled within the subjects receiving their kidneys from the same donor, i.e., when one recipient experienced a large percentage of change after increases of cyclosporine dosing, the corresponding recipient of a kidney from the same donor had a change of the same magnitude. Seven of eight pairs showed a consistent response with respect to a clinically significant increase in serum creatinine concentration of > 15%, with a consistent response purely by chance being < 5%. Thus, the transplanted kidney itself rather than the recipient determines the susceptibility to acute cyclosporine-induced nephrotoxicity.