Dietary fat modifies exercise-dependent glucose transport in
skeletal muscle.
Liu, Sha, Vickie E. Baracos, H. Arthur Quinney, and M. Thomas
Clandinin.
Department of Physical Education and Sport Studies, the Department
of Agricultural, Food and Nutritional Science and the Department of
Medicine, University of Alberta
APStracts 2:0509A, 1995.
Exercise stimulates muscle glucose uptake both directly and by
increasing the sensitivity of this process to insulin. This study was
designed to investigate if the level of dietary fat would interact
with the action of acute exercise, in the presence or absence of
insulin. Weanling female Sprague Dawley rats were fed two levels of
dietary fat (5% vs 20%; w/w) for 6 weeks. Rats were then remained
sedentary or were exercised by a single bout of swimming for a total
of 2 h with 5 min rest intervals each half hour. Basal (insulin
independent) and insulin - stimulated glucose uptake rates were
determined in isolated epitrochlearis muscles using [3H]-3-O-methyl
-glucose. Muscles of sedentary rats fed a high fat diet showed
decreased glucose uptake overall, due to a marked decrease in insulin
- stimulated uptake. Muscles of rats fed a high fat diet also showed
considerable impairment of insulin - dependent glucose uptake
measured both immediately and 3.5 h after exercise. Glucose uptake
was suppressed by 64% at half maximal concentrations of insulin (0.8
nM) and by 34% at maximally stimulating (20 nM) insulin levels. This
lowered sensitivity and response to insulin were not altered by acute
exercise. Glucose uptake in response to acute exercise (insulin -
independent) was quantitatively similar in rats fed high and low fat
diets; rats on a high fat diet, however, showed higher insulin -
independent glucose uptake at 3.5 h after exercise.
Received 30 May 1995; accepted in final form 9 November 1995.
APS Manuscript Number A562-5.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 8 December 95