Barbiturate and amphetamine activity in rats fed a magnesium-deficient diet.

Hexobarbital hypnosis and d-amphetamine toxicity were observed in rats fed a commercially available rat food preparation (lab chow) and in another two groups fed complete nutritionally defined diets with or without magnesium. Neither hexobarbital sleeping time nor hexobarbital blood concentration at awakening were affected after 4, 8 or 12 days of feeding the deficient diet. However, increased sensitivity to d-amphetamine was observed after 11 days of feeding the same magnesium deficient diet to other rats. The LD50 of d-amphetamine in magnesium deficient rats was less than 0.5 that recorded for the groups fed lab chow or the nutritionally defined diet with a magnesium supplement.