REGULATION OF RESPiRATION THE ANTAGONISM BETWEEN METHYLENE BLUE AND SODIUM CYANIDE

In 1917 Thunberg reported a comprehensive series of experi-ments dealing with the effect in vitro of methylene blue and potas-sium cyanide upon oxidase activity. He showed definite antag-onism of the cyanide to the catalytic activity of methylene blue and definite antagonism of the methylene blue to the depressant effect of the cyanide on the oxidase reaction. In the latter respect 50 mgm. of methylene blue scarcely neutralized the depressant effect of 2 mgm. of potassium cyanide. A methylene blue solu-tion was tiot decolorized by potassium cyanide and a chemical reaction between the two substances was not indicated. More recently Sahlin (1926) determined the minimal lethal dose for white mice of methylene blue and potassium cyanide separately and the effect of the latter when it was administered after previous treatment with methylene blue. These experi-ments showed distinct antagonism of the dye to the fatal effects of cyanide. In a previous paper (Eddy, 1930c) we have recorded the effects of methylene blue and of sodium cyanide in connection with the study of the responsiveness of the submaxillary gland. Both agents stimulated respiration; the former increased and the latter decreased the rate of oxygen consumption. Both agents raised the blood pressure; with the former the rise was more marked and more persistent, while with the latter the rise was frequently suc-ceeded by a fall and sometimes only a fall in pressure occurred