Cytochrome oxidase and urate oxidase as intracellular O2 indicators in studies of O2 gradients during hypoxia in liver.

Results obtained from a new approach of investigating O2 distribution in intact perfused liver under hypoxic conditions are presented. Based on the signals observed by organ absorbance spectrophotometry from two compartments with oxidases of markedly different O2 sensitivity, the mitochondria and the peroxisomes, a distribution between high O2 and zero O2 zones is postulated, an intermediate border zone of O2 concentrations between the K0,5 (O2) values being virtually absent (steep intercellular O2 gradients).