Comparison of Enzyme Distribution in Liver of Normal, Fasted and Hypoxic Guinea Pigs

¹ From the Division of Biological and Medical Research, Argonne National Laboratory, Lemont, Illinois

Intermittent hypoxia (16 hr/day for 3 days) resulted in decreases in the succinic dehydrogenase, uricase and catalase activities of guinea pig liver. In the controls fasted to duplicate the weight loss of the hypoxic group, decreases in uricase and catalase but not in succinic dehydrogenase were seen when the activities were expressed on a wet weight basis. Decreases in the enzyme activities per unit nitrogen in fasted animals are attributable to enzyme inactivation with subsequent accumulation of nonenzymatic nitrogen which diluted the existing enzymatic protein. In the hypoxic animals, there was a true loss of liver protein nitrogen. No differences in sedimentation characteristics were found for the particles containing succinic dehydrogenase activity in the normal, fasted or hypoxic livers. Uricase, in the hypoxic liver alone, showed a greatly increased sedimentability, apparently as a result of a change in the physical state of the uricase-containing particles.