Are there oxygen-deficient regions in resting skeletal muscle?.
Toth, Andras, Miklos Pal, Marc E. Tischler, and Paul C. Johnson.
Departments of Physiology and Biochemistry, University of Arizona,
Tucson Arizona, U.S.A.
APStracts 2:0510H, 1995.
The purpose of this study was to determine whether there are local
regions in resting skeletal muscle in which the oxygen delivery is
insufficient to support oxidative metabolism. This hypothesis was
tested by stopping for 5 min. the blood supply to the exteriorized
cat sartorius muscle while monitoring NADH fluorescence in localized
tissue areas 15-25 microns in diameter. A rise in fluorescence was
taken as indicating a shift to anaerobic metabolism. Tissue sites in
the arteriolar and venular regions of the capillary network were
selected for study. Following flow stoppage, fluorescence did not
change for an average of 48+ 22 sec (S.D.) and then rose over a
period of 61+ 27 sec to an average value 55+ 19 % above control for
arteriolar and venular sites combined. Fluorescence began to rise
within 5 sec of flow stasis in only one of the 61 sites and within 10
sec in 2 of the sites. There was no difference in the time course or
magnitude of fluorescence changes at arteriolar and venular sites.
The data indicate that in resting skeletal muscle, oxygen supply
appears sufficient to support oxidative metabolism in over 95% of the
tissue.
Received 14 February 1995; accepted in final form 7 November
1995.
APS Manuscript Number H135-5.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 30 November 95