Sleep cycle disturbances induced by apamin, a selective blocker of Ca(2+)-activated K+ channels.

Intracerebroventricular injections of low doses of apamin, a specific blocker of a class of Ca(2+)-activated K+ channels, induced insomnia and a long-lasting suppression of deep slow sleep and paradoxical sleep. Injected animals showed a late but important rebound of paradoxical sleep. Even after the recovery of a normal sleep amount, the circadian cycle remained disturbed during all the recording duration (96 h).