Journal of Applied Physiology, Vol 72, Issue 6 2435-2445, Copyright © 1992 by American Physiological Society

ARTICLES

Muscle accounts for glucose disposal but not blood lactate appearance during exercise after acclimatization to 4,300 m

G. A. Brooks, E. E. Wolfel, B. M. Groves, P. R. Bender, G. E. Butterfield, A. Cymerman, R. S. Mazzeo, J. R. Sutton, R. R. Wolfe and J. T. Reeves
University of Colorado, Denver 80262.

We hypothesized that the increased blood glucose disappearance (Rd) observed during exercise and after acclimatization to high altitude (4,300 m) could be attributed to net glucose uptake (G) by the legs and that the increased arterial lactate concentration and rate of appearance (Ra) on arrival at altitude and subsequent decrease with acclimatization were caused by changes in net muscle lactate release (L). To evaluate these hypotheses, seven healthy males [23 +/- 2 (SE) yr, 72.2 +/- 1.6 kg], on a controlled diet were studied in the postabsorptive condition at sea level, on acute exposure to 4,300 m, and after 3 wk of acclimatization to 4,300 m. Subjects received a primed-continuous infusion of [6,6-D2]glucose (Brooks et al., J. Appl. Physiol. 70: 919-927, 1991) and [3-13C]lactate (Brooks et al., J. Appl. Physiol. 71:333-341, 1991) and rested for a minimum of 90 min, followed immediately by 45 min of exercise at 101 +/- 3 W, which elicited 51.1 +/- 1% of the sea level peak O2 uptake (65 +/- 2% of both acute altitude and acclimatization peak O2 uptake). Glucose and lactate arteriovenous differences across the legs and arms and leg blood flow were measured. Leg G increased during exercise compared with rest, at altitude compared with sea level, and after acclimatization. Leg G accounted for 27-36% of Rd at rest and essentially all glucose Rd during exercise. A shunting of the blood glucose flux to active muscle during exercise at altitude is indicated. With acute altitude exposure, at 5 min of exercise L was elevated compared with sea level or after acclimatization, but from 15 to 45 min of exercise the pattern and magnitude of L from the legs varied and followed neither the pattern nor the magnitude of responses in arterial lactate concentration or Ra. Leg L accounted for 6-65% of lactate Ra at rest and 17-63% during exercise, but the percent Ra from L was not affected by altitude. Tracer-measured lactate extraction by legs accounted for 10-25% of lactate Rd at rest and 31-83% during exercise. Arms released lactate under all conditions except during exercise with acute exposure to high altitude, when the arms consumed lactate. Both active and inactive muscle beds demonstrated simultaneous lactate extraction and release. We conclude that active skeletal muscle is the predominant site of glucose disposal during exercise and at high altitude but not the sole source of blood lactate during exercise at sea level or high altitude.

This article has been cited by other articles:

				H. B. Nielsen, M. A. Febbraio, P. Ott, P. Krustrup, and N. H. Secher Hepatic lactate uptake versus leg lactate output during exercise in humans J Appl Physiol, October 1, 2007; 103(4): 1227 - 1233. [Abstract] [Full Text] [PDF]

				M. Neya, T. Enoki, Y. Kumai, T. Sugoh, and T. Kawahara The effects of nightly normobaric hypoxia and high intensity training under intermittent normobaric hypoxia on running economy and hemoglobin mass J Appl Physiol, September 1, 2007; 103(3): 828 - 834. [Abstract] [Full Text] [PDF]

				G. van Hall COUNTERPOINT: THE LACTATE PARADOX DOES NOT OCCUR DURING EXERCISE AT HIGH ALTITUDE J Appl Physiol, June 1, 2007; 102(6): 2399 - 2401. [Full Text] [PDF]

				C. Lundby, H. Pilegaard, J. L. Andersen, G. van Hall, M. Sander, and J. A. L. Calbet Acclimatization to 4100 m does not change capillary density or mRNA expression of potential angiogenesis regulatory factors in human skeletal muscle J. Exp. Biol., October 15, 2004; 207(22): 3865 - 3871. [Abstract] [Full Text] [PDF]

				G. C. Henderson, M. A. Horning, S. L. Lehman, E. E. Wolfel, B. C. Bergman, and G. A. Brooks Pyruvate shuttling during rest and exercise before and after endurance training in men J Appl Physiol, July 1, 2004; 97(1): 317 - 325. [Abstract] [Full Text] [PDF]

				P. U. Saunders, R. D. Telford, D. B. Pyne, R. B. Cunningham, C. J. Gore, A. G. Hahn, and J. A. Hawley Improved running economy in elite runners after 20 days of simulated moderate-altitude exposure J Appl Physiol, March 1, 2004; 96(3): 931 - 937. [Abstract] [Full Text] [PDF]

				S. A. Clark, R. J. Aughey, C. J. Gore, A. G. Hahn, N. E. Townsend, T. A. Kinsman, C.-M. Chow, M. J. McKenna, and J. A. Hawley Effects of live high, train low hypoxic exposure on lactate metabolism in trained humans J Appl Physiol, February 1, 2004; 96(2): 517 - 525. [Abstract] [Full Text] [PDF]

				A. Vezzoli, M. Gussoni, F. Greco, and L. Zetta Effects of temperature and extracellular pH on metabolites: kinetics of anaerobic metabolism in resting muscle by 31P- and 1H-NMR spectroscopy J. Exp. Biol., September 1, 2003; 206(17): 3043 - 3052. [Abstract] [Full Text] [PDF]

				G. van Hall, J. A. L. Calbet, H. Sondergaard, and B. Saltin Similar carbohydrate but enhanced lactate utilization during exercise after 9 wk of acclimatization to 5,620 m Am J Physiol Endocrinol Metab, December 1, 2002; 283(6): E1203 - E1213. [Abstract] [Full Text] [PDF]

				K. M. Kelley, J. J. Hamann, C. Navarre, and L. B. Gladden Lactate metabolism in resting and contracting canine skeletal muscle with elevated lactate concentration J Appl Physiol, September 1, 2002; 93(3): 865 - 872. [Abstract] [Full Text] [PDF]

				S. L. Kennedy, W. C. Stanley, A. R. Panchal, and R. S. Mazzeo Alterations in enzymes involved in fat metabolism after acute and chronic altitude exposure J Appl Physiol, January 1, 2001; 90(1): 17 - 22. [Abstract] [Full Text] [PDF]

				M. L. Parolin, L. L. Spriet, E. Hultman, M. P. Matsos, M. G. Hollidge-Horvat, N. L. Jones, and G. J. F. Heigenhauser Effects of PDH activation by dichloroacetate in human skeletal muscle during exercise in hypoxia Am J Physiol Endocrinol Metab, October 1, 2000; 279(4): E752 - E761. [Abstract] [Full Text] [PDF]

				M. L. Parolin, L. L. Spriet, E. Hultman, M. G. Hollidge-Horvat, N. L. Jones, and G. J. F. Heigenhauser Regulation of glycogen phosphorylase and PDH during exercise in human skeletal muscle during hypoxia Am J Physiol Endocrinol Metab, March 1, 2000; 278(3): E522 - E534. [Abstract] [Full Text] [PDF]

				B. C. Bergman, E. E. Wolfel, G. E. Butterfield, G. D. Lopaschuk, G. A. Casazza, M. A. Horning, and G. A. Brooks Active muscle and whole body lactate kinetics after endurance training in men J Appl Physiol, November 1, 1999; 87(5): 1684 - 1696. [Abstract] [Full Text] [PDF]

				G. A. Brooks, M. A. Brown, C. E. Butz, J. P. Sicurello, and H. Dubouchaud Cardiac and skeletal muscle mitochondria have a monocarboxylate transporter MCT1 J Appl Physiol, November 1, 1999; 87(5): 1713 - 1718. [Abstract] [Full Text] [PDF]

				G. A. Brooks, H. Dubouchaud, M. Brown, J. P. Sicurello, and C. E. Butz Role of mitochondrial lactate dehydrogenase and lactate oxidation in the intracellular lactate shuttle PNAS, February 2, 1999; 96(3): 1129 - 1134. [Abstract] [Full Text] [PDF]

				G. C. M. Beaufort-Krol, J. Takens, M. C. Molenkamp, G. B. Smid, K. J. Meuzelaar, W. G. Zijlstra, and J. R. G. Kuipers Increased myocardial lactate oxidation in lambs with aortopulmonary shunts at rest and during exercise Am J Physiol Heart Circ Physiol, November 1, 1998; 275(5): H1503 - H1512. [Abstract] [Full Text] [PDF]

				G. A. Brooks, E. E. Wolfel, G. E. Butterfield, A. Cymerman, A. C. Roberts, R. S. Mazzeo, and J. T. Reeves Poor relationship between arterial [lactate] and leg net release during exercise at 4,300 m altitude Am J Physiol Regulatory Integrative Comp Physiol, October 1, 1998; 275(4): R1192 - R1201. [Abstract] [Full Text] [PDF]

				G. B. McClelland, P. W. Hochachka, and J.-M. Weber Carbohydrate utilization during exercise after high-altitude acclimation: A new perspective PNAS, August 18, 1998; 95(17): 10288 - 10293. [Abstract] [Full Text] [PDF]

				L. A. Bertocci, J. G. Jones, C. R. Malloy, R. G. Victor, and G. D. Thomas Oxidation of lactate and acetate in rat skeletal muscle: analysis by 13C-nuclear magnetic resonance spectroscopy J Appl Physiol, July 1, 1997; 83(1): 32 - 39. [Abstract] [Full Text] [PDF]

				B. D. Levine and J. Stray-Gundersen "Living high-training low": effect of moderate-altitude acclimatization with low-altitude training on performance J Appl Physiol, July 1, 1997; 83(1): 102 - 112. [Abstract] [Full Text] [PDF]

				G. B. McClelland and G. A. Brooks Changes in MCT 1, MCT 4, and LDH expression are tissue specific in rats after long-term hypobaric hypoxia J Appl Physiol, April 1, 2002; 92(4): 1573 - 1584. [Abstract] [Full Text] [PDF]