Renal transplantation promptly restores excretory function but disturbed L-arginine metabolism persists in patients during the early period after surgery.

The synthesis and whole body metabolism of L-arginine (Arg) are disturbed in renal diseases. Renal transplantation represents the best therapy in the end-stage of these diseases. In the present we compared alterations of plasma Arg and related compounds with renal excretory function in patients with end-stage renal disease, before and after kidney transplantation. Arg, asymmetric dimethylarginine (ADMA), citrulline (Cit), glutamine (Gln), ornithine (Orn), phenylalanine (Phe), tyrosine (Tyr), urea, creatinine, albumin, and nitrate were analyzed in patients before, immediately after (0-time) and 1, 2, 3, 7 and 14 days following living donors kidney transplantation. Healthy subjects were controls. Glomerular filtration rate (GFR) and amino acid molar ratios were calculated. Before transplantation creatinine, urea, Cit, Gln, ADMA, and nitrate were above, while GFR and Arg were below controls, confirming disturbed excretory and metabolic renal functions in patients with renal disease. Renal transplantation promptly normalized creatinine, urea, GFR, Cit, and nitrate. However, regardless of increased molar Phe/Tyr ratios, indicating increased net protein catabolism in peripheral tissues, low Arg and elevated ADMA concentrations persisted throughout the examined period. Alterations of other amino acids also suggest similarly disturbed Arg metabolism in patients after kidney transplantation. In conclusion, renal transplant promptly restored its excretory function, but increased net protein catabolism, disturbed Arg metabolism and endothelial dysfunction in entire body of these patients were not improved throughout the early period after the operation. That has to be considered in their therapy.