Vascular adaptations in rat hindlimb skeletal muscle after
voluntary running-wheel exercise.
Sexton, William L.
Department of Physiology, Kirksville College of Osteopathic
Medicine, 800 W. Jefferson Street, Kirksville, MO 63501
APStracts 2:0097A, 1995.
To test the hypothesis that voluntary running-wheel exercise would
elicit vascular adaptations in rat skeletal muscle, male Sprague
-Dawley rats (202 +/- 5 g) were either cage-confined (C, n=11) or
housed in cages with free access to running-wheels (R, n=13) for 12
wks. Vascular transport capacity was determined in maximally
vasodilated (papaverine) hindquarters of C and R with measurements of
total and regional (radiolabeled microspheres) flow capacity and
capillary filtration coefficient (CFC). R voluntarily ran 29 +/- 4
km/wk over the 12 wk period; however, performance of individual rats
varied greatly (range 4 to 74 km/wk). Citrate synthase activity was
increased in the medial head (81%, P<0.001) and the red long
head (88%, P<0.001) of the triceps brachii muscle in R, but not
in the white long head (25%, P=0.06). CFC was 27% greater in R
compared to C (0.040 +/- 0.003 vs. 0.031 +/- 0.002 ml x min-1 x 100
g-1 x mmHg, P<0.001) suggesting there was an increase in
microvascular surface area available for fluid exchange. Total
hindquarters flow was increased in R (P<0.05) at all perfusion
pressures examined indicative of an increased flow capacity. Regional
flows revealed that skin flow was unchanged in R, and that the
increase in total flow was due to increased skeletal muscle flow
capacity. These results indicate that voluntary running wheel
exercise elicits adaptive increases in skeletal muscle vascular
transport capacity and oxidative capacity comparable to that seen in
treadmill trained rats, and support the use of voluntary running
-wheel exercise as a less stressful training modality in exercise
studies using rats.
Received 17 June 1994; accepted in final form 6 March 1995.
APS Manuscript Number A598-4.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 21 March 1995.