Synergistic Effect of Certain Amino Acid Pairs upon Insulin Secretion in Man

Individual amino acids were administered intravenously in amounts of 15 gm. and again together with 15 gm. of a second amino acid as 30-gm. mixtures. Synergism in the stimulation of the release of insulin was demonstrated when the sum of the increases in plasma insulin which resulted from the separate infusions of two amino acids was exceeded by that obtained when they were administered as a mixture. A synergistic effect was exerted by arginine and leucine, arginine and phenylalanine, but not by arginine and lysine, arginine and histidine, or by leucine and histidine. Synergism was greater with arginine and leucine than with arginine and phenylalanine. It appears to result from the effects of these amino acid pairs upon the pancreatic beta cell.