AJP - Gastrointestinal and Liver Physiology, Vol 264, Issue 2 375-G382, Copyright © 1993 by American Physiological Society
Measurement of redox states of mitochondrial cytochrome aa3 in regions of liver lobule by reflectance microspectroscopy
S. S. Chen, H. Yoshihara, N. Harada, A. Seiyama, M. Watanabe, H. Kosaka, S. Kawano, H. Fusamoto, T. Kamada and T. Shiga
Department of Physiology, Osaka University Medical School, Japan.
To evaluate the sublobular distribution of oxygen tension, the redox states
of mitochondrial cytochrome aa3 were assessed in local regions of the liver
lobule by reflectance microspectroscopy. The reflected light from two
focused microspots (20 microns in diam) on the surface of the perfused
liver, placed on the stage of microscope, was conducted to the
spectrophotometer with two separate light guides, giving the reflectance
spectra. The redox state of cytochrome aa3 was calculated from the
difference in reflectance between 603 and 630 nm. The degree of cytochrome
reduction increased with the stepwise decline of the influent or effluent
oxygen concentrations. The local oxygen concentration in periportal region
for the half-maximal reduction of cytochrome aa3 was higher than that in
pericentral region. In addition, the degree of cytochrome aa3 reduction
increased with the distance from the periportal region, reflecting a
physiological gradient of oxygen tension along the sinusoidal flow,
although with an intersinusoidal heterogeneity within liver lobule.
