RNA metabolism in uremic patients: accumulation of modified ribonucleosides in uremic serum. Technical note

To determine the metabolism of ribonucleic acid (RNA) in uremia, serum and urine levels of ribonucleosides in uremic patients were analyzed using reversed-phase high-performance liquid chromatography. The serum levels of xanthosine and all modified ribonucleosides were increased in undialyzed patients with chronic renal failure (CRF), and patients undergoing hemodialysis (HD) and continuous ambulatory peritoneal dialysis (CAPD). The serum level of pseudouridine was markedly increased in all the uremic patients especially CAPD patients (32 times higher than normal). By contrast, the serum level of adenosine did not show any significant change in the uremic patients. Interestingly, the serum and urine levels of inosine were significantly decreased in all the uremic patients, suggesting that the production of inosine is decreased in uremic patients. The serum level of uridine was significantly elevated only in the HD patients. The serum levels of all ribonucleosides except inosine and uridine decreased significantly after HD. The urinary excretion of inosine, 1-methyladenosine, 1-methylguanosine, N2,N2-dimethylguanosine and N4-acetylcytidine was significantly decreased in the CRF patients, leading to the accumulation of these modified ribonucleosides in the uremic serum. CAPD patients showed markedly increased serum levels of modified ribonucleosides such as pseudouridine, 1-methylinosine, and N2,N2-dimethylguanosine and N4-acetylcytidine as compared with the HD patients. These results demonstrate that there was an altered metabolism of RNA in uremic patients with marked accumulation of modified ribonucleosides.