LIVER AND HEART MITOCHONDRIAL SUCCINATE-DEHYDROGENASE ACTIVITY OF NEWBORN RATS IN ANOXIC HYPOXIA AND STARVATION

Succinate dehydrogenase [EC 1.3.99.1] activity was determined in the liver and heart of newborn rats after 3 and 48 h exposure to anoxic hypoxia (10% O2) and after 48 h starvation. Control determinations were made on newborn animals of corresponding ages, full term fetuses (21 days), infantile (1 and 2 wk) and full grown animals. Hypoxia for 3 h had no influence on succinate dehydrogenase activity at all in either the heart or liver mitochondria of the newborn animals. After 48 h no difference was observed in the liver between the hypoxid animals and the starved controls of the same age, though starvation itself had resulted in a significant increase in activity, as much as 42%. When liver mitochondria succinate dehydrogenase in normal mitochondria was activated by preincubation of mitochondria with the substrate, the activity increase obtained was greater than that resulting from starvation. The increase in activity in the heart of the hypoxic or starved animals was not significant (< 10%).