The effects of "autonomic drugs" on villous movement in the small intestine of the pigeon.

1. The responses of pigeon duodenal villi to intravenous injection or local application of "autonomic drugs" were studied and compared with those reported in dogs by other workers.2. Choline esters, anticholinesterases, noradrenaline, adrenaline and nicotine all stimulated villous movement in the pigeon. Similar responses to these drugs have been reported in the dog. The effects of these drugs on villous activity could be inhibited by pretreatment of the bird with suitable antagonists, although hexamethonium was ineffective in preventing the effects of nicotine. Some of the antagonists also stimulated the villi.3. Isoprenaline caused inhibition of villous movements, which could be prevented by pretreatment of the bird with propranolol. It appears that in pigeons the villi have both alpha-adrenoceptors, stimulation of which increases villous activity, and beta-adrenoceptors, stimulation of which depresses villous movements.