The metabolic effects of glucagon infusion in normoglycaemic and hypoglycaemic small-for-gestational-age infants. II. Changes in plasma amino acids.

Altogether 17 individual amino acids were determined before and during glucagon infusion in normoglycaemic and hypoglycaemic SGA infants. The magnitude and time course of the response in total plasma amino acids to glucagon infusion (0.2 microng/kg/min for four hours) differed in the two groups: while in the normoglycaemic SGA infants a significant hypoaminoacidaemia was noted by the second hour of glucagon infusion, in the hypoglycaemic newborns no appreciable changes were observed. In the former group altogether twelve amino acids showed a progressive and significant decline. The fall of three important gluconeogenic amino acids alanine, glycine,proline, and that of three branched chain amino acids was particularly striking. In contrast, in the hypoglycaemic infants the amino acids were not significantly affected by glucagon infusion. This unresponsiveness of plasma amino acids was probably transient as judged from the moderate hypoaminoacidaemia noted by the end of the infusion period. The observations seem to have important implications regarding the influence of glucagon on hepatic glucose production, and its possible therapeutic importance in the management of hypoglycaemic intrauterine malnourished infants.