Estimation of the convulsive effect of cyanide in rats

Convulsions are frequently observed in severe, acute cyanide intoxication. The mechanisms involved are not well known. In the present study, the convulsive effect of cyanide was examined in the rat by means of a dose threshold determination after infusion of cyanide. An optimal dose rate of 1.80 mg/min./kg was determined. By infusing this optimal dose rate it was possible to divide another cyanide-treated group of rats into two groups: one without and another with convulsions. After the experiment all animals were killed by exposure to high intensity microwave irradiation. Regional dopamine, noradrenaline and main dopamine metabolites were isolated and analyzed using high pressure liquid chromatography and electrochemical detection. Striatal noradrenaline was decreased but dopamine and its metabolites were increased in rats infused with cyanide at the optimal dose rate until the convulsions started. Animals infused with the threshold dose at the optimal dose rate did not show any significant changes in noradrenaline or in dopamine metabolites, but all animals showing convulsions also had increased striatal dopamine levels. Thus changes in dopamine appear to be dependent on convulsions.