Experimental hepatic encephalopathy. Changes of the level of wakefulness in the rat with portacaval shunt.

The level of wakefulness in rats with portacaval shunt has been evaluated by measurement of the reactivity of the reticulocortical system by electric stimulation of the brain stem reticular formation during slow wave sleep. The voltage level of stimulus necessary to provoke cortical awakening is significantly decreased after portacaval shunt. This modification of the level of wakefulness is in accordance with the diminution of total sleep and the decrease in threshold of reaction to painful stimuli observed in rats after portacaval shunt. The measurement of the reactivity of the reticulocortical system is a simple procedure which permits quantification of post-shunt encephalopathy in the rat.