L-Arginine Supplementation Improves Function and Reduces Inflammation in Renal Allografts

Abstract. Recovery from ischemia/reperfusion and immune-mediated injury in the renal transplant is associated with reduced renal hemodynamics and increased leukocyte infiltration. In diverse models of renal failure, L-arginine supplementation improved hemodynamics and reduced inflammation. However in a proinflammatory environment, L-arginine can worsen renal injury. This study investigated the therapeutic potential of L-arginine supplementation in allogeneic renal transplantation: Brown Norway rat kidneys were transplanted into Lewis rat recipients, with one native kidney remaining. Recipients received low-dose cyclosporin A (2.5 mg/kg per d subcutaneously) to obtain moderate vascular and interstitial rejection, with or without 1% L-arginine in drinking water for 7 d posttransplantation. Transplantation increased renal vasoconstriction (from 16.9 ± 1.33 to 35.1 ± 8.6 units; P < 0.01), thereby reducing GFR (from 0.96 ± 0.09 to 0.48 ± 0.10 ml/min; P < 0.05). Treatment with L-arginine restored renal graft function to levels found in normal donors (renal vascular resistance, 15.7 ± 1.69 units; GFR, 0.80 ± 0.06 ml/min). L-arginine significantly reduced vascular occlusion because of less inflammation, endothelial disruption, and thrombosis. L-arginine also decreased tubulitis, interstitial injury, and macrophage infiltration. These protective effects suggest that L-arginine might be useful as additive therapy to conventional immune suppression.