Determination of myoglobin saturation of frozen specimens using a
reflecting cryospectrophotometer.
Voter, William A., and Thomas E. J. Gayeski.
University of Rochester Medical Center, Department of
Anesthesiology, Rochester N.Y. 14642,
APStracts 2:0162H, 1995.
This report describes a method and instrumentation for determining
myoglobin (Mb) oxygen saturation in skeletal muscle. Canine gracilis
is frozen in situ using a liquid N2-cooled copper block. Transverse
section surfaces of frozen, unstained muscle are observed at _110_C
using a microspectrophotometric system. The Mb saturation is
determined using epi-illumination and a four-wavelength optical
method. A special aperture permits illumination of a 20 [mu]m square
area and the radius of the catchment volume is estimated to be about
60 [mu]m with the strongest signal arising from the central region.
The equibestic wavelengths used were 546.6, 570.5 and 584.1 nm. The
method was validated using the nonlinear multicomponent analysis
method of L[umlaut]ubbers. Endpoint (0% and 100% saturation)
calibration was set using ischemic and adenosine treated, highly
-oxygenated muscles, respectively. The effects of Hb and metMb signal
contamination were evaluated experimentally and by computer mixing
simulations. Mb saturation determinations adjacent to large vessels
are to be avoided. MetMb and capillary Hb do not interfere with the
determination. The reproducibility of the method is estimated to be
+/-5%.
Received 8 August 1994; accepted in final form 7 March 1995.
APS Manuscript Number H702-4.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 2 May 1995.