Age-dependence of succinate dehydrogenase (SDH) in rat liver and its inducibility after barbital and phenylbutazone pretreatment.

SDH activity in liver homogenates increases threetimes from one day before to one day after birth. The plateau till the 13th day of life is followed by a minimum on the 15th day of life, thereafter the increase leads to a maximum on the 120th day. The influence of phenylbutazone and barbital on body and liver weight as well as on hepatic SDH activity was investigated in different age groups. Both drugs were administered in three single daily doses, phenylbutazone additionally 31 days long. Hepatic SDH activity based on liver wet weight or liver protein did not change in any of the experimental groups. But as a consequence of increased liver body weight ratio (mostly non-significant), hepatic activity per gram body weight exhibited a tendency to higher values.