[Alterations in the isozyme spectrum and the activity of lactate dehydrogenase in development of Ehrlich ascites tumor].

By means of polyacrylamide gel disc electrophoresis lactate dehydrogenase belonging only to the M-type was observed in mice liver tissue, muscles, ascite cells and ascites fluid in the course of development of Ehrlich ascites tumor. In the tissues studied and in the tumor the LDH type was not altered in the course of development of the tumor. At the same time the LDH activity was slightly decreased in muscles; in the terminal period it was increased in liver tissue; in ascitic cells or fluid it was increased in the course of development of the tumor. In blood serum the M-fraction was the main type of LDH. The M4 isozyme accounted for about 80% of the total LDH activity. The remainding 20% were distributed approximately equally between the other four isozymes. As the disease proceeded redistribution of isozymes occurred in the direction of the M-type. About 70% of the H-type LDH was found in heart; isozymes H4 and H3M accounted for about 35% each of the total LDH-activity. Direct relation was not observed between the alteration in the enzymatic activity and the LDH isozyme spectrum in tumor and tissues of animals with developing Ehrlich ascites tumor.