The effect of certain phenothiazine derivatives on respiratory phosphorylation in the cardiac muscle of the rabbit

Summary Phenothiazine derivatives, mepazine and promazine, when added to homogenates of cardiac muscle of the rabbit in a concentration of 0.8·10^–3M, cause a rise in the efficacy of oxidative phosphorylation, increasing the P and the P: O coefficient. In a 1.2·10^–3M, concentration of mepazine and promazine P is reduced, though to a lesser degree than O₂, the P: O coefficient remaining slightly above the normal level.A 0.8·10^–3M phenergan concentration uniformly reduces both respiration and phosphorylation. With a further rise of the phenergan concentration phosphorylation decreases more sharply than respiration. High concentrations of mepazine, phenergan and promazine (1.6·10^–3M) sharply depress phosphocreatine formation and cause a decrease of P: O. The phenothiazine derivatives neither depress creatine kinase nor activate adenosinetriphosphatase.(Presented by Active Member AMN SSSR S. E. Severin) Translated from Byulleten Èksperimental'noi Biologii i Meditsiny Vol. 49, No. 4, pp. 60–63, April, 1960