Noninvasive measures of oxidative metabolism on working human
muscles by near infrared spectroscopy with continuous wave
(nircws).
Hamaoka, Takafumi, Hisao Iwane, Teruichi Shimomitsu, Toshihito
Katsumura, Norio Murase, Shinya Nishio, Takuya Osada, Yuko Kurosawa,
and Britton Chance.
Department of Preventive Medicine and Public Health, Tokyo Medical
College, Tokyo, 160, Japan; Department of Biochemistry and
Biophysics, University of Pennsylvania, Philadelphia, Pennsylvania
19104
APStracts 3:0240A, 1996.
The purpose of this study was to determine whether the initial rate of
hemoglobin and myoglobin (Hb/Mb) deoxygenation during immediate post
-exercise ischemia, a reflection of muscle oxygen consumption (m-VO2),
can be a quantitative measure of muscle oxidative metabolism. The
finger flexor muscles of five healthy males (aged 25-31 yrs.) were
monitored by 31P magnetic resonance spectroscopy for changes in
phosphocreatine (PCr), inorganic phosphate (Pi), and pH. Tests were
conducted during 15 minutes of cuff ischemia and during 5 minutes
submaximal isotonic grip exercise at 10%, 20%, 30%, and 40% of
maximal voluntary contraction (MVC), one contraction every 4 seconds
The m-VO2 changes were also monitored by near infrared spectroscopy
with continuous wave (NIRcws). The m-VO2 during exercise was
expressed relative to the resting value. The resting metabolic rate,
calculated from the PCr breakdown rate after complete O2 depletion,
was 0.0073+/-0.0010 (mean+/-SD) mMATP.sec-1. During submaximal
exercise (pH>6.9), the m-VO2 increased with a rise in intensity
(0.036+/-0.011, 0.054+/-0.016, 0.062+/-0.012, and 0.067+/-0.020
mMATP.sec-1 during 10%MVC, 20%MVC, 30%MVC, and 40%MVC, respectively),
and showed significant correlation with changes in both calculated
ADP and PCr values (r2=0.98 and r2=0.99, respectively). In
conclusion, because of the significant correlation with regulatory
metabolites (ADP and PCr) of oxidative phosphorylation, O2 decline
rate in immediate post-exercise ischemia determined by NIRcws can be
utilized for the quantitative evaluation of localized muscle
oxidative metabolism.
Received 25 August 1995; accepted in final form 24 April 1996.
APS Manuscript Number A929-5.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 28 May 96