Diabetes, Vol 46, Issue 11 1805-1812, Copyright © 1997 by American Diabetes Association

ARTICLES

Insulin-independent acute restoration of euglycemia normalizes the impaired glucose clearance during exercise in diabetic dogs

SJ Fisher, M Lekas, ZQ Shi, D Bilinski, G Carvalho, A Giacca and M Vranic
Department of Physiology, Faculty of Medicine, University of Toronto, Ontario, Canada.

At rest and during exercise, chronic hyperglycemia, high free fatty acid (FFA) oxidation, and insulin deficiency in diabetes are well known to impair glucose clearance (metabolic clearance rate [MCR]). The effect of acute restoration of glycemia per se on MCR has been less well characterized. We therefore studied normal and alloxan-diabetic dogs both at rest and during exercise, as diabetic hyperglycemic or after acutely induced euglycemia (<160 min) generated by infusion of either insulin or phlorizin. Glucose uptake was similar under hyperglycemic and normoglycemic conditions both at rest and during exercise, indicating a precise balance between the mass effect of glucose and decreased MCR. Rest and exercise MCR was fourfold lower under conditions of hyperglycemia, but insulin-independent restoration of euglycemia improved basal MCR threefold and normalized MCR during exercise. High FFA turnover did not affect glucose uptake but was correlated with plasma lactate concentrations (r = 0.72, P < 0.001), suggesting that muscle fuel requirements are controlled by glucose oxidation and not uptake. We conclude that in alloxan-diabetic dogs, the impaired MCR may be an adaptive phenomenon because correction of hyperglycemia corrects MCR despite partial insulin deficiency and high FFA turnover. We speculate that constant glucose uptake despite hyperglycemia in diabetes may protect the muscle from excessive exposure to glucose.
CiteULike    Del.icio.us    Digg    Reddit    Technorati    What's this?

This article has been cited by other articles:

				C. Rantzau, M. Christopher, and F. P. Alford Contrasting effects of exercise, AICAR, and increased fatty acid supply on in vivo and skeletal muscle glucose metabolism J Appl Physiol, February 1, 2008; 104(2): 363 - 370. [Abstract] [Full Text] [PDF]

				M. J. Christopher, C. Rantzau, G. McConell, B. E. Kemp, and F. P. Alford Prevailing hyperglycemia is critical in the regulation of glucose metabolism during exercise in poorly controlled alloxan-diabetic dogs J Appl Physiol, March 1, 2005; 98(3): 930 - 939. [Abstract] [Full Text] [PDF]

				M. J. Christopher, Z.-P. Chen, C. Rantzau, B. E. Kemp, and F. P. Alford Skeletal muscle basal AMP-activated protein kinase activity is chronically elevated in alloxan-diabetic dogs: impact of exercise J Appl Physiol, October 1, 2003; 95(4): 1523 - 1530. [Abstract] [Full Text] [PDF]

				K. Shum, K. Inouye, O. Chan, J. Mathoo, D. Bilinski, S. G. Matthews, and M. Vranic Effects of antecedent hypoglycemia, hyperinsulinemia, and excess corticosterone on hypoglycemic counterregulation Am J Physiol Endocrinol Metab, September 1, 2001; 281(3): E455 - E465. [Abstract] [Full Text] [PDF]

				M. C. Lekas, S. J. Fisher, B. El-Bahrani, M. van Delangeryt, M. Vranic, and Z. Q. Shi Glucose uptake during centrally induced stress is insulin independent and enhanced by adrenergic blockade J Appl Physiol, August 1, 1999; 87(2): 722 - 731. [Abstract] [Full Text] [PDF]