Journal of Applied Physiology, Vol 68, Issue 6 2329-2336, Copyright © 1990 by American Physiological Society
Microvascular injury after ischemia and reperfusion in skeletal muscle of exercise-trained rats
W. L. Sexton, R. J. Korthuis and M. H. Laughlin
Department of Veterinary Biomedical Sciences, University of Missouri, Columbia 65211.
Ischemia and reperfusion in skeletal muscle is associated with increases in
total vascular resistance (Rt) and the microvascular permeability to plasma
proteins. To determine whether exercise training can attenuate ischemia and
reperfusion-induced microvascular injury in skeletal muscle, intact (with
skin) and skinned, maximally vasodilated (papaverine), isolated
hindquarters of control (C) and exercise-trained (ET) rats were subjected
to ischemia (intact 120 min; skinned 60 min) followed by 60 min of
reperfusion. ET rats ran on a motorized treadmill at 32 m/min (8% grade), 2
h/day for 12 wk, whereas the C rats were cage confined. Before ischemia, ET
hindquarters had higher isogravimetric flow, lower Rt, and similar solvent
drag reflection coefficients (sigma f) compared with C. During reperfusion
in intact hindquarters, flow was higher (P less than 0.05) and Rt tended to
be lower (15 +/- 2 vs. 25 +/- 5 mmHg.ml-1.min.100 g; P less than 0.1) in ET
compared with C; however, in skinned hindquarters flow and Rt (14 +/- 2 vs.
13 +/- 2 mmHg.ml-1.min.100 g) were not different between C and ET. During
reperfusion, sigma f was reduced (P less than 0.05) in both intact (C 0.68
+/- 0.03; ET 0.68 +/- 0.02) and skinned (C 0.66 +/- 0.03; ET 0.68 +/- 0.03)
hindquarters, indicative of an increased microvascular permeability to
plasma proteins. These results indicate that exercise training did not
attenuate the microvascular injury (increased Rt and decreased sigma f)
associated with ischemia and reperfusion in rat skeletal muscle.
