QUANTITATIVE-ANALYSIS OF REDOX GRADIENT WITHIN THE RAT-LIVER ACINI BYFLUORESCENCE IMAGES - EFFECTS OF GLUCAGON PERFUSION

The redox gradient along the sinusoid in the rat liver was studied usi ng a redox scanner, a device based on tissue fluorescence scanning spe ctroscopy measuring the fluorescence signals of oxidized flavoprotein (FP) and reduced pyridine nucleotide (PN). The FP/(FP + PN) ratio refl ects the mitochiondrial redox state in the liver tissue. The distribut ion of mitochondrial redox state on the scanned area is expressed as t wo-dimensional gray-scale images with a 20 mu m resolution. Using this instrument, we have scanned a 2.5 X 2.5 mm area of the frozen rat liv er sample to investigate the redox gradient within acini and the effec ts of glucagon on the changes in the redox distribution. The redox ima ges obtained in the perfused livers showed mosaic patterns implicating a regular heterogeneity of redox state in an acinus. The analysis of gradient curve, furthermore, clarified that the redox level in an acin us decreased sigmoidally from the periportal to the pericentral region . Glucagon, which has been reported to reduce the intracellular redox state, decreased the redox potential in whole acini, especially, in th e periportal region, when compared with the perfusion without glucagon . These results strongly indicate an intraacinus heterogeneity of gluc agon function, with glucagon selectively operating in the upstream of the sinusoid.