Effect of a nucleoside-nucleotide mixture on protein metabolism in rats after seventy percent hepatectomy.

The effect of a nucleoside-based mixture (OG-VI) on protein synthesis in partially hepatectomized rats was evaluated. Twenty male Wistar rats weighing about 200 g underwent 70% hepatectomy by Higgins and Anderson's method, and then were subjected to total parenteral nutrition (TPN) for 3 days: the control group received only standard TPN (S-TPN group) and the experiment group received standard TPN supplemented with a nucleoside-nucleotide mixture (13% W/V, OG-VI) (OG-TPN group). The rates of whole body protein turnover and protein synthesis and breakdown were determined for 3 days after hepatectomy by the method of Picou and Taylor-Roberts with [15N] glycine. The nitrogen balances on days 1 and 3 and the cumulative nitrogen balance were significantly higher in the OG-TPN group than in the control group. Moreover, the rates of protein turnover and protein synthesis were significantly higher in the OG-TPN group than in the control group. Thus, increase in protein synthesis, rather than change in protein breakdown, was concluded to be responsible for the better nitrogen balance of the OG-TPN group. These findings suggest that the nucleoside-nucleotide mixture was used for the syntheses of RNA and DNA through the salvage pathway in regenerating liver and that this resulted in enhanced protein turnover with simultaneous increase in protein synthesis.