Resistance of Hepatic Lysosomes, Mitochondria and Microsomes of Protoporphyrin-Administered Rats to Peroxidative Damage

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Antioxidative inhibition by protoporphyrin (PP) of peroxidative damage in lysosomes, mitochondria and microsomes of rat liver was investigated at 24h after an intravenous administration of PP. Using a lysosome-containing (3500×g) fraction, the release of lysosomal marker enzymes, acid phosphatase and aryl sulfatase, from lysosome which had been stimulated by L-ascorbic acid (AsA), was decreased dose-dependently, as was the inhibition of lipid peroxidation by PP in the fraction. Swelling of mitochondria induced by Fe²⁺ and AsA was also inhibited in the PP-injected rat. In microsomes, lipid peroxidation stimulated by AsA caused a decrease in activity of a microsomal marker enzyme, glucose 6-phosphatase, and in P450 content. The extent of the decrease by AsA, both in activity and content, was diminished in PP-administered rat liver microsomes. These results indicate that PP protects those subcellular fractions from deterioration by lipid peroxidation.