EFFECTS OF IV AMINO-ACIDS ON HUMAN SPLANCHNIC AND WHOLE-BODY OXYGEN-CONSUMPTION, BLOOD-FLOW, AND BLOOD TEMPERATURES

The thermic effect of amino acid administration was examined in health y subjects. Pulmonary and splanchnic oxygen uptake, cardiac output, sp lanchnic blood flow, and blood temperatures were measured in eight hea lthy men before and during 2.5 h of intravenous infusion of 600 kJ of a mixture of 19 amino acids. Indirect calorimetry and catheter techniq ues were used, including thermometry in arterial and a hepatic venous blood. During the infusion, pulmonary oxygen uptake rose progressively from a basal value of 269 +/- 6 to 321 +/- 8 ml/min after 2.5 h. The splanchnic oxygen consumption increased from a basal level of 64 +/- 4 to a peak value of 91 +/- 7 ml/min after 2 h of infusion. The 2.5 h a verage splanchnic proportion of the amino acid-induced whole body ther mogenesis was 51 +/- 11%. Cardiac output increased from 6.2 +/- 0.3 in the basal state to 7.3 +/- 0.4 l/min, whereas the splanchnic blood fl ow remained unchanged during the infusion period. The arteriohepatic v enous oxygen difference increased from 51 +/- 4 in the basal state to 65 +/- 5 ml/l after 2 h of amino acid infusion. The blood temperature rose by similar to 0.25 degrees C during the amino acid infusion, refl ecting an increased heat accumulation in the body. It is concluded tha t the splanchnic tissues account for approximately one-half of the ami no acid-induced whole body thermogenesis, that amino acid infusion aug ments blood flow in the extrasplanchnic but not in the splanchnic tiss ues, and stimulates the accumulation of heat in the body most likely v ia a resetting of the central thermosensors.