TISSUE LACTIC DEHYDROGENASE ISOZYMES DEVELOPMENTAL PATTERNS IN THE NEONATAL RAT

Abstract
The isozyme forms of lactic dehydrogenase (LDH) were studied in excised rat tissues up to 45 days after birth. The predominant subtype at birth was the muscle form, reflecting anaerobic glycolysis. Development was characterized by an increase in the relative ratio of heart (H) to muscle (M) in all tissues studied; however, the major form in liver and muscle was quite clearly the M type. Emergence of the typical adult LDH distribution would appear to be complete in 2–3 weeks after birth, but the adult levels of total LDH activity were not attained during the 45 postnatal days of this study.