Protoporphyrin-induced photodamage to mitochondria and lysosomes from rat liver.

Preparations of mitochondria and lysosomes from rat liver were irradiated (340--380 nm) with light doses up to 80 kJ/m2 in the presence of 180 nmol/l protoporphyrin. ADP-stimulated respiration and succinate oxidation were inhibited before there was any significant release or inhibition of lysosomal enzymes. The results suggest that, rather than lysosomal lysis, damage to mitochondria may be the primary event in erythropoietic protoporphyria.