EFFECT OF INTRAVENOUS L-ALANINE ADMINISTRATION ON PLASMA GLUCOSE, INSULIN AND GLUCAGON, BLOOD PYRUVATE, LACTATE AND BETA-HYDROXYBUTYRATE CONCENTRATIONS IN NEWBORN INFANTS Study in Term and Preterm Newborn Infants

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Abstract
Term [10] and preterm [11] newborn infants with appropriate weights for their gestational age were infused for 1 min with L-alanine (150 mg/kg) at the age of 29-76 h (mean 48 h) and circulating levels of glucose, lactate, pyruvate, D-.beta.-hydroxybutyrate (D-BOHB), insulin and glucagon were monitored. Plasma glucose concentrations increased from 2.7 .+-. 0.16 (mean .+-. SEM [standard error of the mean]) to 3.7 .+-. 0.2 mmol/l after 50 min (P < 0.01) in term infants. In preterm infants, after an initial decrease of the glucose level from 3.1 .+-. 0.16 to 2.6 .+-. 0.16 mmol/l (P < 0.05), it returned to the baseline level at 50 min: 3.0 .+-. 0.2 mmol/l. The blood concentration of D-BOHB decreased in term infants from 192 .+-. 37 to 112 .+-. 6 .mu.M/l (P < 0.01) after 40 min. In preterms, its decrease was not significant (P > 0.05). Plasma glucagon levels rose from 53 .+-. 5 to 70 .+-. 8 pmol/l after 10 min (P < 0.01) in term infants and from 61 .+-. 6 to 75 .+-. 9 after 20 min (P < 0.01) in preterm infants. There were no significant changes in plasma insulin concentrations in either group. Forty minutes after L-alanine infusion I/G [insulin/glucagon] ratios were lower in preterm infants (1.26 .+-. 0.14) than in term infants (1.71 .+-. 0.25) (P < 0.01). There was no relationship between the glycemic responses to L-alanine and the basal levels of D-BOHB. The glycemic effect of L-alanine infusion and circulating glucagon may depend upon a specific stage in maturation. The antiketogenic effect of L-alanine infusion is observed in term infants as in adults.