Myogenic peristalsis in isolated preparations of chicken oesophagus

Abstract

1 Nicotine, 20 μg/ml, briefly and partially blocked the longitudinal contractions of a chick vagus nerve-oesophagus preparation to nerve stimulation, but potentiated them in the presence of hyoscine, 10 μg/ml. 2 Strychnine, 20 μg/ml, antagonized the longitudinal contractions of the chick oesophagus to nerve stimulation, though not to acetylcholine or 5-hydroxytryptamine. Hyoscine, 10 μg/ml, enhanced the nerve-blocking action of strychnine. 3 These observations suggest that in the vagus nerve of the chicken, hyoscine either blocks certain types of fibre selectively or interacts with pharmacological receptors for strychnine and nicotine. 4 Tetrodotoxin, 1 μg/ml, propranolol, 40 μg/ml, cocaine, 200 μg/ml, or strychnine, 100 μg/ml, which render autonomic nerves inexcitable, potentiated the spontaneous movements of isolated preparations of chicken oesophagus at normal intra-luminal pressure; they also potentiated peristaltic response to increased intra-luminal pressure. 5 These observations suggest that the preparations contain intramural nerves that inhibit the musculature. 6 Peristalsis in the chicken oesophagus was unaffected by nicotine, 20 μg/ml, tubocurarine, 20 μg/ml, hyoscine, 10 μg/ml, phentolamine, 1 μg/ml, propranolol, 0·5 μg/ml, mepyramine, 1 μg/ml, methysergide, 0·1 μg/ml, and morphine, 20 μg/ml. It was produced in preparations of chicken oesophagus after removal of the mucous membrane. Papaverine, 20 μg/ml, inhibited the peristalsis and had a spasmolytic action in the musculature. 7 These observations suggest that the peristalsis in isolated preparations of chicken oesophagus is dependent solely upon myogenic contractility.