Effects of phenobarbital on activity of mitochondrial enzymes in peripheral blood lymphocytes and oxidative phosphorylation in liver mitochondria.

Treatment with phenobarbital (30 mg/kg) for 2 weeks increased succinate dehydrogenase activity in peripheral blood lymphocytes of male rats. In 38% phenobarbital-treated rats succinate-cytochrome c oxidoreductase activity was lower than in the control due to accumulation of cells exhibiting no enzyme activity; in 44% animals this parameter was higher than in the control. The rates of state 3 respiration (oxidation substrate succinate), phosphorylation, and uncoupled respiration in liver mitochondria (oxidation substrate glutamate/malate mixture) increased after 35-day treatment with phenobarbital. The respiratory control and ADP/O ratio for these substrates did not differ from the control.