ETHANOL INDUCES HETEROGENEOUS REDUCTION OF CYTOCHROME AA(3) WITHIN PERFUSED-RAT-LIVER LOBULE ASSESSED USING MICROSPECTROSCOPY

The redox state of cytochrome aa(3) was measured at microspots (20 mu m diameter) within the lobule of perfused rat livers, using reflectanc e microspectroscopy, and the effect of ethanol infusion on sublobular distribution of the redox states was evaluated. A sigmoidal relationsh ip was observed between oxygen delivery and the reduction of cytochrom e aa(3) in both the periportal and pericentral regions of the liver lo bule when the influent O-2 concentration was decreased in a graduated manner. This sigmoidal curve was shifted to the more reduced state by ethanol infusion, with ethanol (25-100mM) increasing the degree of cyt ochrome aa(3) reduction in a dose-dependent manner according to the di stance from the periportal region along a sinusoid. This increase was spatially heterogeneous within a liver lobule. These data indicate tha t ethanol accelerates cytochrome aa(3) reduction, with a distinct grad ient of reduction along sinusoids but a heterogeneous distribution wit hin the liver lobule.