Mechanism of Methylene Blue in CO-Poisoning

Abstract

In order to see what effect methylene blue had upon the form of the hemoglobin in rabbits poisoned with CO, spectrophotometric analyses were made on blood at regular time intervals up to 20 minutes after removal of the animal from the gas chamber. Each rabbit was allowed to remain in an atmosphere of CO plus air, (% composition not determined) until it was unconscious and barely breathing, but not long enough to cause death. CO₂ was absorbed by soda lime. The animal was then taken out, a heart puncture made and 2 drops of blood immediately placed in a small tube filled to the brim with a measured amount of 0.4% NH₄OH. This was then tightly stoppered with paraffined corks excluding air, and shaken to cause complete hemolysis. A 0.03% methylene blue solution (Merck's medicinal) dissolved in 0.9% NaCl was then injected intravenously, 1 cc. per kg., one minute after the animal had been removed from the CO chamber. Heart punctures were made 2, 4, 7, 11, 16 and 21 minutes later and samples collected as described above. Control animals were either given injections of 0.9% NaCl alone or no injections. There was no difference in the observed values between the 2 types of controls. Ten animals in each series were used. The probable error of the mean readings at each time was less than 1%. The disappearance of CO-hemoglobin and reappearance of oxyhemoglobin was then followed by spectrophotometric readings of the blood samples. The method described in previous papers 1 was used, the ratio of the extinction coefficients at 540 and 560 mμ being determined. This indicates the per cent oxyhemoglobin as compared with CO-hemoglobin present. Table I shows the progressive change in the proportion of the total hemoglobin present, the remainder in each case being CO-hemoglobin.

This shows the rapid change from CO-hemoglobin to oxyhemoglobin in the case of the treated animals as compared with the slower change for the controls.