Plasma alanine: Relation to plasma glucose, glucagon, and insulin in the neonate

An attempt was made to determine if correlations exist among plasma concentrations of alanine, the major amino acid substrate for gluconeogenesis, and plasma concentrations of glucose, glucagon, and insulin in normal newborn infants. The effects of an intravenous infusion of cl-alanine (1 mMl/kg) to six neonates was also determined. Although a peak in alanine concentration coincided with a nadir in glucose concentration at 12 hours of life, no correlation existed between the observed changes in alanine and glucose, or alanine and glucagon. Infused alanine caused increases in both plasma glucose and glucagon concentrations, as in the adult; the responses, however, were of small magnitude. Our data indicate that reduced blood glucose concentrations in the normal newborn infant are not due to a deficiency of alanine substrate for gluconeogenesis. And, although alanine stimulates secretion of glucagon, there is no consistent correlation between plasma alanine and glucose, or plasma alanine and glucagon concentrations during the early neonatal period. thus the key factors in control of glucose concentrations in the newborn period cannot be deduced from simple relationships of these plasma constituents.