Nucleotides and nucleosides are essential components in all cells. However, nucleotides have not been supplied in parenteral nutrition regimens. We developed a well-balanced nucleoside-nucleotide mixture "OG-VI" and examined its effect in animals under some stressed conditions. OG-VI was composed of 30 mmol/l of inosine, 30 mmol/l of guanosine monophosphate, 30 mmol/l of cytidine, 22.5 mmol/l of uridine and 7.4 mmol/l of thymidine. The whole body protein turnover increased significantly in rats receiving total parenteral nutrition (TPN) with OG-VI solution after 70% hepatectomy, compared with rats receiving normal TPN without OG-VI (122.1 +/- 20.9 mgN.kg-1.h-1 vs. 97.4 +/- 10.1 mgN.kg-1.h-1, P < 0.01, n = 10). OG-VI significantly enhanced protein synthesis while it did not decrease protein breakdown. The effect of OG-VI on myocardium after hypoxic challenge was also examined in rats. The creatine phosphate (PCr)/inorganic phosphate (Pi) was decreased in normal rat myocardium after hypoxic challenge. However, in the rats administered OG-VI, PCr/Pi was maintained at baseline level and did not decrease after hypoxia. There was no significant change in the level of adenosine triphosphate (ATP) between before and after hypoxic challenge in myocardium of the rats administered OG-VI. In the rats receiving normal saline, instead of OG-VI, the ATP level decreased significantly after hypoxic challenge (4132 +/- 276 nmol/g tissue, n = 3, vs. 3439 +/- 465 nmol/g tissue, n = 5, P < 0.05). These data suggested that the well-balanced nucleoside-nucleotide mixture, OG-VI improved nitrogen metabolism and might stimulate synthesis of high-energy phosphate in recovery after severe surgical stress.