Effects of Methylene Blue on Respiratory Metabolism of the Rat

Abstract

Methylene blue exerts definite effects in the metabolism of excised tissue.1 It is therefore of importance to determine the action of methylene blue in the intact animal. The respiratory metabolism of 6 rats was studied by means of a Haldane open circuit apparatus after various periods of fasting. Then 0.5 cc. M/100 methylene blue per 100 gm. of body weight was injected intraperitoneally. The CO2 production and O2 consumption were measured for varying periods during the following 48 hours. The results in all 6 animals bear a striking similarity. The composite graph depicts the observations of the 4 animals that were in the postabsorptive condition.The graph discloses that there is a fall in the R.Q. which is followed by a subsequent rise. The early fall in the quotient is caused in part by a diminished production of CO2 and partly by an increased consumption of O2. The greater O2 uptake indicates that the decreased production of CO2 occurs despite an increased pulmonary ventilation. The fall of the R.Q. c...