Retrograde amnesia induced by hypoxia and electroconvulsive shock in two rat strains.

Hypoxia or electroconvulsive shock (ECS) was administered to two strains of rats following one trial passive avoidance training. ECS produced retrograde amnesia in the Blue Spruce Farms Long Evans hooded rat when administered within 10 sec after training and in the Charles River albino rat when administered within 75 sec after training. Hypoxia was effective in producing retrograde amnesia when administered up to 40 min after training in the hooded rat but only when administered between 20 and 30 min after training in the albino rat. The importance of strain variability is discussed.