L-arginine reverses the antinatriuretic effect of cyclosporin in renal transplant patients.

Background. Cyclosporin has been shown to facilitate renal vasoconstriction and to have an antinatriuretic eect. The existence of an interference of cyclosporin with the vasodilating properties of endothelium medi- Introduction ated by nitric oxide production could mediate these eects. On the other hand, the infusion of the nitric The immunosuppressive drug cyclosporin A (CsA) is oxide precursor L-arginine has been shown to induce widely used in human organ transplantation [1,2]. renal vasodilatation and to facilitate natriuresis in While very eective in preventing graft rejection CsA normal volunteers. We have investigated the renal administration can induce an acute impairment of eects of the administration of an infusion of renal function completely reversible upon dose reducL-arginine in renal transplant patients chronically tion or withdrawal of the drug [3‐5 ]. Preglomerular treated with cyclosporin. To facilitate the analysis of vasoconstriction seems to be after the acute impairment the data the eects of the administration of a similar in renal function which is characterized by a fall in dose of cyclosporin on renal function during the infusion renal plasma flow, glomerular filtration rate, and in of a vehicle were also investigated during the administra