Effects of cholinomimetic drugs and their antagonists injected into vertebral artery of unanaesthetized dogs.

In unanaesthetized dogs, cholinomimetic drugs and their antagonists, catecholamines and 5HT were injected into vertebral artery placed in a skin loop. Acetylcholine (1 mg), pilocarpine (1-2 mg), nicotine (250-500 microng), eserine (100 microng) and neostigmine (250 microng) produced sleep apart from a few other peripheral effects. Sleep for longer periods followed injections of tubocurarine (1 mg), atropine (50 microng) and hexamethonium (500 microng). Adrenaline (50 microng) and noradrenaline (50-250 microng) did not produce significant effects on behaviour and sleep. 5HT (250-500 microng) also caused sleep.