Heat Production from Human Erythrocytes in Relation to their Metabolism of Glucose and Amino Acids

Abstract

Erythrocytes were incubated in two synthetic incubation media, one of which contained amino acids in addition to the basic constituents of albumin, salt, and glucose. Incubations were performed for up to % hours at 37°C. The heat production (HP) was determined using a flow microcalorimeter. It was found to be higher during the early stages of the incubation. After 12 h a steady state level was attained. The excess HP during the first parts of the incubations correlated closely to the glucose consumption and lactate production, which were determined in parallel. Changes in the concentration of other metabolites of the glycolytic pathway were found to give only minor contributions to the HP. Of the amino acids analyzed only tryptophan was consumed at a significant rate. This might have contributed to the HP during the first hour. Production of alanine was also found. At present the energy source of the steady state HP occurring in the erythrocytes after 12 h, and which persists for up to three days or more, is unknown. The present data demonstrate that only one-third of heat produced by erythrocytes in a glucose-containing medium is derived from glycolysis via the Embden-Meyerhof pathway.

Key Words:

• Amino acid metabolism
• calorimetry
• erythrocyte metabolism
• glucose metabolism