REGULATION OF RESPIRATION THE ANTAGONISM BETWEEN METHYLENE BLUE AND SODIUM CYANIDE

¹ From the Department of Physiology of the University of Michigan, Ann Arbor, Michigan, and the Department of Physiology and Pharmacology of the University of Alberta, Edmonton, Alberta, Canada

In the anesthetized dog doses of 0.5 cc. per kilogram of m/100 solution of sodium cyanide repeated at intervals of ten to thirty minutes produced like effects upon respiration, blood pressure and salivary secretion. The same dose given ten minutes after the administration of 1 cc. per kilogram of 1 per cent solution of methylene blue, had very little or no effect upon any one of these functions. If the same dose of cyanide was given forty-five minutes after the methylene blue, the sodium cyanide effects reappeared but were still less than before the administration of the dye.

Respiration was increased by methylene blue if it was administered when the rate of oxygen consumption was normal. But respiration was decreased by methylene blue if it was administered when the rate of oxygen consumption was below normal, reduced by the injection of cyanide.

This reaction of the respiratory mechanism is paralleled by the reaction of the submaxillary gland to oxygen. Salivary secretion was increased by an increased percentage of oxygen in the inspired air if oxidations had been proceeding normally. But salivary secretion was decreased by an increased percentage of oxygen in the inspired air if oxidations had been reduced by prolonged low oxygen inhalation.

The quickly fatal intravenous dose of sodium cyanide for the anesthetized dog was found to be 3 mgm., 3 cc. of m/50 solution, per kilogram of body weight.

The effects of such a dose of cyanide were reduced greatly and the animal survived if methylene blue, l0mgm. per kilogram, was injected into the femoral vein ten minutes before or not more than two minutes after the cyanide.