Janus Green B Causing Functional Disturbances in Mitochondria in Mg<SUP>2+</SUP>-containing Medium

Abstract

ABSTRACT.The effect of Janus green B was investigated on respiration and Mitochondria are stained specifically with Janus green B (JGB) in supravital staining (6,15, 24). Lazarow and Cooperstein (5, 12, 13) reported that JGB disperses diffusely in the cytoplasm and that the mitochondria appear greenish-blue because of JGB oxidation by the cytochrome oxidase system. Thus JGB remains in an oxidized form in mitochondria but is in a reduced, colorless leucobase in the cytoplasm. Showacre and DuBuy (20), however, showed that the dye accumulates rapidly in mitochondria and is hardly detectable in other cytoplasmic fractions. These investigators showed that mitochondria in living cells have loci for absorption of JGB and that the oxidases in mitochondria may play a role in keeping the dye in an oxidized state (20). Seno et al. (18) also suggested that the dye accumulates in mitochondria in an electron microscopic study. These cells were fixed with fixatives containing Nessler's reagent by which JGB became electron dense and insoluble in water. Braun et al. (1) and Holland (22) found in rat liver mitochondria that more than 90 % of JGB particles were bound to a specific lipoprotein fraction containing coenzyme Q. These findings indicate that the JGB staining of mitochondria is closely related to the mitochondrial membrane components.The oxidation-reduction potential of the dye is -0.256 V at pH 7.0 (11). Therefore, it is possible that the dye interferes with the electron transport system inducing disturbances of mitochondrial function (22). Some dyes including JGB are known to arrest phosphorylation without inhibiting oxygen uptake (8, 11). Dianzani and Scuro (8) reported that JGB hardly stimulates latent ATPase activity. This indicates that the action of the dye should differ from that of dinitrophenol. Thus, the mechanism of JGB disturbance of mitochondrial function is still not clear.In this paper the functional disturbance and swelling of mitochondria by JGB are 29