Changes in the liver lactate dehydrogenase isozyme profile after induced glycogenolysis.

Treatment with cystamine, phlorrhizin or nicotinic acid, which induced liver glycogenolysis, resulted in the increase of liver lactate dehydrogenase activity. This increase was counteracted by the administration of cycloheximide or actinomycin D and coincided with the increase os isozymes 4 and 3 and the decrease of isozyme 5. The enhancement of liver lactate dehydrogenase activity and the changes observed in the isozyme profile were similar to those observed after starvation. These results suggest that the changes in the lactate dehydrogenase isozyme profile found after cystamine, phlorrhizin or nicotinic acid administration may be related to the glycogenolytic effect of these compounds. These result in an adaptation of the liver lactate dehydrogenase to gluconeogenesis.