AJP - Endocrinology and Metabolism, Vol 240, Issue 2 155-E165, Copyright © 1981 by American Physiological Society

ARTICLES

[U-14C]glucose, -alanine, and -leucine oxidation in rats at rest and two intensities of running

T. P. White and G. A. Brooks

The oxidations of injected [U-14C]glucose, [U-14C]alanine, and [U-14C]leucine were investigated in laboratory rats during rest or 2 h of easy and hard treadmill running. After [U-14C]glucose injection, the rate and magnitude of 14CO2 evolution were relatively low at rest and increased as a linear function of metabolic rate (VO2). Evolution of 14CO2 after [U-14C]alanine injection was faster and larger during exercise than rest. The peak of alanine decarboxylation occurred before glucose and, therefore, did not reflect conversion of alanine to glucose prior to decarboxylation. The rate and magnitude of 14CO2 evolution after [U-14C]leucine injection were proportional to metabolic rate, but less than after glucose or alanine injection. During exercise, levels of alanine and leucine in muscle and blood were unchanged or elevated compared to rest. During exercise, alanine levels were unchanged or increased in liver. Liver leucine levels were depressed when exercise began, but increased toward control values during exercise. The metabolism of selected amino acids is joined to carbon flow sustaining exercise.

This article has been cited by other articles:

				M. Korach-Andre, Y. Burelle, F. Peronnet, D. Massicotte, C. Lavoie, and C. Hillaire-Marcel Differential metabolic fate of the carbon skeleton and amino-N of [13C]alanine and [15N]alanine ingested during prolonged exercise J Appl Physiol, August 1, 2002; 93(2): 499 - 504. [Abstract] [Full Text] [PDF]

				A. E. Halseth, P. J. Flakoll, E. K. Reed, A. B. Messina, M. G. Krishna, D. B. Lacy, P. E. Williams, and D. H. Wasserman Effect of physical activity and fasting on gut and liver proteolysis in the dog Am J Physiol Endocrinol Metab, December 1, 1997; 273(6): E1073 - E1082. [Abstract] [Full Text] [PDF]