RENAL EFFECTS OF AMINO-ACIDS AND DOPAMINE IN RENAL-TRANSPLANT RECIPIENTS TREATED WITH OR WITHOUT CYCLOSPORINE-A

1. The nephrotoxic effects of cyclosporin A may diminish the ability o f the transplanted kidney to increase the glomerular filtration rate a nd effective renal plasma flow during infusion of dopamine or amino ac ids. 2. The present study included 16 renal transplant recipients tran splanted for more than 6 months, Eight of the patients were on. immuno suppressive treatment including cyclosporin A [cyclosporin A group; cy closporin A dose, 2.7+/-0.4 mg/kg; S-creatinine, 105+/-12 mu mol/l (me ans+/-SEM)], whereas eight patients had never received cyclosporin A ( non-cyclosporin A group; S-creatinine, 89+/-6 mu mol/l). The renal res ponse to infusion of dopamine and of amino acids was investigated on t wo separate days, All clearance measurements were carried out at nadir cyclosporin A blood levels. 3. Effective renal plasma flow increased significantly in the non-cyclosporin A group and cyclosporin A group b y 31.0+/-4.1% and 35.9+/-6.6%, respectively, during infusion of dopami ne, and by 18.7+/-6.7% and 13.9+/-5.3%, respectively, during infusion of amino acids, Glomerular filtration rate increased significantly in the non-cyclosporin A group and cyclosporin A group by 15.7+/-33% and 18.3+/-4.7%, respectively, during infusion of dopamine, and by 18.9+/- 4.5% and 15.0+/-3.7%, respectively, during infusion of amino acids. 4. Furthermore, the amino acid- and dopamine-induced increases in proxim al tubular outflow (renal clearance of lithium) and calculated changes in renal proximal and distal tubular handling of sodium (and water) w ere comparable between the two groups of patients, Dopamine caused sig nificant natriuresis in both groups, 5. In conclusion, low-dose cyclos porin A seems not to attenuate the renal haemodynamic and tubular resp onse to infusions of amino acids and of dopamine in renal transplant r ecipients with a good graft function.