AJP - Regulatory, Integrative and Comparative Physiology, Vol 255, Issue 1 38-R41, Copyright © 1988 by American Physiological Society

ARTICLES

Liver fructose 2,6-bisphosphate in rats running at different treadmill speeds

W. W. Winder, H. T. Yang and J. Arogyasami
Department of Zoology, Brigham Young University, Provo, Utah 84602.

To determine the effect of work rate on liver fructose 2,6-bisphosphate (fructose 2,6-P2), rats were run for 5 min on a treadmill up a 15% grade at 16, 21, 26, 31, and 36 m/min. The liver content of fructose 2,6-P2 decreased 25, 42, 50, 62, and 71% from resting values after 5 min of running at these work rates. The time course of the decline in liver fructose 2,6-P2 was also studied in rats run at 16 m/min for times ranging from 5 to 100 min, at 23 m/min for times ranging from 5 to 60 min, and at 31 m/min for times of 5, 10, and 20 min. The hepatic content of fructose 2,6-P2 declined significantly after 5 min in all three groups of rats. The rate of decline was greatest in rats run at 31 m/min. After 100 min of running, fructose 2,6-P2 in livers of rats running at 16 m/min declined to levels seen in rats run at 31 m/min for 20 min. Changes in fructose 2,6-P2 occurred before a detectable decline in liver glycogen and in the absence of any significant change in blood glucose. Liver adenosine 3',5'-cyclic monophosphate (cAMP) was elevated after 5 min of exercise in rats running at 23 and 31 m/min but not in rats running at 16 m/min. By the end of exercise, hepatic cAMP was elevated in rats running at all speeds. The rapid decline in fructose 2,6-P2 probably plays a role in decreasing hepatic glycolysis, thereby ensuring that glucose 6-phosphate derived from glycogenolysis is diverted to blood glucose.

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				C. L. Carlson and W. W. Winder Liver AMP-activated protein kinase and acetyl-CoA carboxylase during and after exercise J Appl Physiol, February 1, 1999; 86(2): 669 - 674. [Abstract] [Full Text] [PDF]