Effect of "drugs for liver disease" on hepatotoxic action of carbon tetrachloride. II. Effect of protoporphyrin and phosphorylcholine on microsomal drug-metabolizing enzyme activities and the components in injuried liver.

The effect of "drugs for liver disease", protoporphyrin (PP) and phosphorylcholine (PC), on CCl4-induced liver injury was studied. Attention was given to the levels of microsomal drug-metabolizing enzyme and lipolytic enzyme activities and of some microsomal components such as phospholipid and peroxides. Administration of PP to CCl4-poisoned rats was found to increase the decreased microsomal drug-metabolizing enzyme activities, aminopyrine N-demethylase, aniline p-hydroxylase, cytochrome P-450 and b5 and lipolytic enzyme activity in CCl4-poisoned liver (12-20% increase as compared with those of the poisoned rats), and returned to control levels earlier than in CCl4-poisoned rats. Furthermore, administration of PP to CCl4-poisoned rats caused a decrease in the lipid peroxidation. A single dose of PP to normal rats was shown to increase these parameters, to a small extent. One of the mechanisms may be attributed to the fact that PP increases the biosynthesis of the hemoproteins by means of the incorporation of PP into the pigments and protects the membranes from lipid peroxides and the free radicals. On the other hand, administration of PC to the poisoned rats did not enhance the levels of the drug-metabolizing enzyme activities except for aminopyrine N-demethylase. Phospholipid phosphorous content, however, increased by 13-14% when PC was given. Thus, it is considered that PC may enhance the reconstitution of phospholipids in the injured membrane.