Renal oxygen consumption, thermogenesis, and amino acid utilization during i.v. infusion of amino acids in man

Abstract

The renal contribution to the amino acid-induced whole body thermogenesis was examined. Using indirect calorimetry and catheter techniques, pulmonary and renal oxygen uptake and blood flow, blood temperatures, and net renal exchange of amino acids, glucose and lactate were measured in eight healthy men before and during 3 h of intravenous infusion of 720 kJ of an amino acid solution. During the infusion, the pulmonary oxygen uptake increased from 252 +/- 12 to 310 +/- 8 ml/min, cardiac output increased from 5.9 +/- 0.3 to 6.8 +/- 0.3 l/min, and the arterial blood temperature increased from 36.34 +/- 0.04 to 36.68 +/- 0.07 degrees C. Renal oxygen consumption, heat production, blood flow, and net glucose exchange remained unchanged during the infusion. The net renal uptake of amino acid energy from the blood rose from 2 +/- 2 to 11 +/- 4 W. The total renal energy expenditure was 9-10 W throughout the study period. It is concluded that intravenous amino acid infusion greatly augments the uptake and utilization of amino acids in the kidneys but does not stimulate the renal oxygen consumption, heat production, blood flow, or glucose release.