INSULIN-RESPONSE TO AMINO-ACID AND GLUCOSE INTRAVENOUS INFUSIONS IN DAIRY-COWS - SYNERGISTIC EFFECT

The effect of 30 minute intravenous infusions of amino acids (90 or 18 0 g) or glucose (114 g or 228 g) was studied in five non-pregnant lact ating dairy cows. At each dose the same amounts of energy were deliver ed by glucose or amino acids. The nutrients were infused separately or in combination. In response to each nutrient, plasma insulin increase d proportionally to the dose infused. The increase induced by amino ac ids was lower than that induced by glucose, and plasma insulin returne d to its baseline value more rapidly after amino acid than after gluco se infusion. The hypoglycemia that developed after amino acid infusion s partly explains the short-lived amino acid induced in insulin respon se. The plasma insulin increase which resulted from the glucose-amino acid mix significantly exceeded that obtained by separate but isocalor ic infusions of amino acids or glucose. Therefore, amino acids and glu cose acted synergistically to increase plasma insulin release. The mec hanism leading to the synergistic effect would be partially due to a p ermissive effect of hyperglycemia. Other possible potentiating mechani sms are discussed.