Effects of simultaneous or prior infusion of sugars on the fate of infused protein hydrolysates.

Glucose usually is included in amino acid solutions for intravenous infusion. This has seemed desirable because the amino acids can spare body protein only when sufficient calories are provided. Although the calories so gained (usually 200 for a liter of hydrolysate) are far from enough for this purpose, they do add to the total and besides they might serve particularly efficiently being presented at the same time as the amino acids. On the other hand Elman and his co-workers (1) have reported improved retention of the nitrogen of a partial hydrolysate when fructose replaced the usual glucose. In explanation these writers suggest that the cellular uptake of the glucose is relatively too late to spare the amino acids optimally, whereas the fructose is metabolized more quickly. The present study was undertaken to compare the effects of glucose and fructose on the fate of the amino acids and peptides of infused hydrolysates. We have found that the presence of either sugar in certain commercial protein hydrolysates interferes with the tissue utilization of the peptides present; the effect increases in the order 10 per cent fructose, 5 per cent glucose, 10 per cent glucose. It is completely avoided if the sugars are added to the hydrolysate sterilely just before infusion or if the sugars are infused in advance of the hydrolysate. Therefore, we conclude that substances which interfere with peptide utilization are formed during autoclaving by interaction between the sugars and constituents of the hydrolysate.