Effect Of An Intravenous Histidine Load On Plasma Level Of Other Amino-Acids

Thirteen normal subjects have been given an intravenous load of l -histidine (75 mg/kg body weight). Plasma amino acids were measured before, and 1, 2 and 3 h following the load. At one hour most amino acids had an increased level in plasma. Alanine showed the largest increase and this amino acid is frequently found to be abnormal in histidinaemia. The rapid fall in branched chain and aromatic amino acids seen after an oral histidine load, which was thought to be due to a flow of these compounds into the intestine, was not observed when the histidine was administered intravenously. The plasma concentration of nearly all the amino acids fell below the baseline level in the later specimens. It is believed that this could be due to an increased secretion of growth hormone.