Regional changes in capillary supply in skeletal muscle of high
-intensity, endurance trained rats.
Gute, Dean, Charles Fraga, M. Harold Laughlin, John F. Amann.
Department of Veterinary Biomedical Sciences, University of
Missouri, College of Veterinary Medicine, Columbia, MO 65211
APStracts 3:0126A, 1996.
The objective of this study was to test the hypothesis that an
endurance training program designed to produce recruitment of all
extensor muscle fiber types during each exercise bout would stimulate
capillary angiogenesis throughout rat gastrocnemius and soleus
muscles. Male Sprague-Dawley rats were exercise trained 5 days/wk for
12 - 14 wks with exercise bouts consisting of a combination of high
intensity (32 m/min, on a 15 % incline) and long duration (90
min/day). Upon completion of training (HIET) or cage activity (SED),
rat hindquarters were vascularly isolated and perfusion fixed with a
modified Karnovsky's fixative. Capillary supply was measured in
soleus and gastrocnemius muscles using Olympus Cue 2 image analyzer
software. Capillary supply was reflected in measurements of
capillary/fiber ratio (C/F), capillary numerical density (CND),
capillary surface area density (CSAD), and capillary volume density
(CVD) on transversely cut tissue sections. HIET increased citrate
synthase activity by 20% and 42% in the medial and long heads of the
triceps brachii, respectively. Sarcomere lengths were similar in
gastrocnemius and soleus muscles of SED and HIET rats following
fixation. All four indices of capillary supply were significantly
greater throughout the gastrocnemius muscle of HIET rats as compared
to SED values. The relative increase in capillarity was greater in
white than in red gastrocnemius muscle of HIET rats. HIET also
increased capillary supply of soleus muscle. However, only CND was
statistically greater (19%) in HIET soleus as compared to SED. These
results support the hypothesis that this training program would
produce an increase in capillary supply in all extensor muscles.
Received 21 September 1995; accepted in final form 19 February
1996.
APS Manuscript Number A1027-5.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 13 March 96