Effects of organophosphorous compounds, oximes and atropine injected into the third ventricle of unanaesthetized dogs

摘要

The effects of four organophosphorous compounds, three oximes and atropine sulphate, injected through an indwelling cannula into the third ventricle of unanaesthetized dogs were examined. The effects of 200 μg of dyflos were involuntary micturition, defaecation, akinesia of hind limbs and pronounced disturbances of awareness; those of 100 μg of ethyl pyrophosphate were tremor, restlessness and signs of fear; 500 μg to 5 mg of dyflos and 250 μg to 500 μg of ethyl pyrophosphate caused vomiting, salivation, twitches of facial muscles and recurrent epileptiform seizures. The injection of 40 to 80 mg of dimefox and of 50 mg of schradan elicited involuntary micturition, vomiting, salivation and defaecation. These effects occur probably after these substances have passed into the blood stream and have been converted in the liver to potent anticholinesterases. This view is supported by the finding of reduced blood cholinesterase activity. At a dose level of 12.5 mg, 1,1'-trimethylenebis(4-hydroxyiminomethylpyridinium bromide) produced strong convulsions. At this dose level pralidoxime iodide and diacetyl monoxime produced no observable effects. Atropine sulphate in a dose of 1 mg caused disturbances in consciousness and behaviour followed by convulsions. Intraventricular atropine and to a minor extent intraventricular oximes were able to antagonize the effects of intraventricular ethyl pyrophosphate. Pralidoxime iodide exerted a strong antagonistic effect also on intravenous injection.