Effect of Methylene Blue and Cyanide on Respiration of Cerebral Cortex,Testicle,Liver and Kidney

Abstract

The respiratory metabolism of tissues of various organs was studied in the Warburg respiration apparatus. The tissues were suspended in a phosphate medium buffered at pH 7.4 with lactate as the substrate. Three different samples of methylene blue were used and, with each, a diminution of O₂ uptake was observed in 47 experiments on the cerebral cortex of rat, dog and cat. Whenever methylene blue was added to the solution the CO₂ production of the surviving brain tissue was decreased to a greater extent than the O₂ consumption; the respiratory quotient therefore fell.

Cyanide, on the other hand, caused a diminution in the O₂ uptake of excised cortex in each of 66 observations. The decrease in CO₂ output was usually similar for equal concentrations of cyanide and varied inversely with the concentration of cyanide. However, the decrease in O₂ consumption varied from observation to observation even if the concentration of cyanide was kept the same. Since the O₂ uptake varied, the respiratory quotient after treatment with cyanide fluctuated.

Even though cyanide and methylene blue separately decreased O₂ uptake, in the presence of both substances the oxygen consumption tended to return to the normal value. The fact that the CO₂ consumption is so small is evidence that the oxidations activated by methylene blue do not proceed in the usual manner. A characteristic experiment is presented in the table (Exp. 1).

The results of 6 observations of the testicle are similar to those found on the brain (Exp. 2).

In 16 experiments on the kidney, methylene blue produced a diminished oxygen consumption without any constant effects on the R.Q. Similarly cyanide decreased the oxygen uptake, but, in those experiments in which methylene blue was added, this was raised again toward the normal value (Exp. 3).