COBALT COMPOUNDS AS ANTIDOTES FOR HYDROCYANIC ACID

The antidotal potency of a cobalt salt (acetate), of dicobalt edetate, of hydroxocobalamin and of cobinamide against hydrocyanic acid was examined mainly on mice and rabbits. All the compounds were active antidotes for up to twice the LD50; under some conditions for larger doses. The most successful was cobalt acetate for rabbits (5xLD50), which was effective at a molar cyanide/cobalt (CN/Co) ratio of 5, but had as a side-effect intense purgation. Hydroxocobalamin was irregular in action, but on the whole was most effective for mice (4.5xLD50 at a molar ratio of 1), and had no apparent side effects. Dicobalt edetate, at molar ratios of up to 2, was more effective for rabbits (3xLD50) than for mice (2xLD50), but had fewer side effects than cobalt acetate. The effect of thiosulphate was to augment the efficacy of dicobalt edetate and, in mice, that of hydroxocobalamin; but, apparently, in rabbits, to reduce that of hydroxocobalamin. Cobinamide, at a molar ratio of 1, was slightly more effective than hydroxocobalamin on rabbits and also less irregular in its action. Cobalt acetate by mouth was effective against orally administered hydrocyanic acid. The oxygen uptake of the body, reduced by cyanide, is rapidly reinstated when one of the cobalt antidotes has been successfully administered.

PULMONARY AND CENTRAL NERVOUS SYSTEM DAMAGE IN RATS EXPOSED TO HYPERBARIC OXYGEN AND PROTECTION THEREFROM BY GAMMA-AMINOBUTYRIC ACID

Male Wistar rats were exposed to oxygen at 6 atmospheres absolute pressure for periods of 30 and 40 minutes and the effect of the intraperitoneal administration of γ-aminobutyric acid (GABA) (20 mmoles/kg) and glucose (15 mmoles/kg) on the toxic effects of OHP was studied. GABA protected the animals against both gross lung damage and convulsions, but glucose was without effect. Since the accumulation of fluid in the peritoneal cavity was similar for GABA and glucose injections, it would appear that the protective action of GABA was not due to this influx of fluid into the peritoneal cavity brought about by the injected material. All animals having gross pulmonary pathology had suffered severe seizures during the exposure to OHP, but severe convulsions can occur without the incidence of pulmonary pathology. The significance of these observations is discussed.