A hyoscine‐resistant contraction of isolated chicken oesophagus in response to stimulation of parasympathetic nerves

Abstract

1 . Contractions of the chicken isolated oesophagus or separated external muscle produced by stimulation of the vagus and descending oesophageal nerves were abolished by hyoscine (1–100 μg/ml.) if the duration of stimulation was less than 5 sec, but prolonged stimulation produced delayed contractions not antagonized by hyoscine. 2 . The contractions to nerve stimulation were abolished by nerve section but not by bretylium, hexamethonium or tubocurarine. 3 . In decerebrate chickens, intravenous hyoscine abolished the contractions of the oesophagus produced by nerve stimulation, but previous intravenous injection of hyoscine into chicks did not prevent subsequently isolated oesophageal preparations from contracting to nerve stimulation. 4 . Prolonged nerve stimulation of an isolated oesophageal preparation did not produce a contraction from a piece of isolated guinea-pig ileum or post-crop chick oesophagus suspended in the same organ-bath. 5 . It seems possible that small amounts of a slow contracting substance were released from the stimulated nerves together with acetylcholine.