The gastric motility patterns induced by direct and reflex excitation of the vagus nerves in the anaesthetized ferret

Abstract

1. Under urethane anaesthesia the ferret has a stomach which exhibited spontaneous contractions. The amplitude of the contractions was reduced, but never abolished, by vagotomy, atropine or hexamethonium. 2. Electrical stimulation of the cut peripheral end of the cervical or abdominal vagus nerves activated both excitatory and inhibitory fibres, whereas reflex activation by stomach distension or by cytoglucopenia was predominantly excitatory on gastric motility. The magnitude of the response to electrical stimulation was dependent upon the stimulus frequency, duration and voltage. Stimulation for periods longer than 10 sec at 10 Hz caused an increase in tone and motility which declined almost to control values if it was sufficiently prolonged. 3. Short duration stimulation, 10 sec or less, at 10 Hz produced a single gastric contraction. An identical response could only be produced if a period of rest from 30 to 120 sec separated two such stimuli. 4. The frequency of gastric contractions was independent of the frequency of nerve stimulation. 5. Using a divided stomach, vagal non-cholinergic, non-adrenergic fibres were shown to cause mainly relaxation of the corpus region. Similar fibres supplied the antrum and their activation caused inhibition of spontaneous contractions. The transmitter may be 'purinergic' as rebound contractions were observed.