Ability of exogenous alanine to lower blood beta-hydroxybutyrate during development in rats.

The intraperitoneal injection of L-alanine into 10- and 21-day-old fed Wistar rats resulted in blood alanine levels of 3-5 mM and in a rapid, significant decrease in the concentration of beta-hydroxybutyrate (betaOHB) in blood. The drop in betaOHB was unrelated to changes in the concentrations of pyruvate, lactate, or glucose. The intraperitoneal injection of glutamate at the same age had no effect on betaOHB values. In 2-day-old pups and in older weaned animals, the injection of alanine had either no effect or increased the levels of betaOHB in blood. The most rapid disappearance of exogenous alanine occurred in 35-day-old and not in 10- and 21-day-old rats. These data suggest that alanine has a depressant effect on the level of circulating betaOHB at a specific stage in the animal's maturation.