Sympathetic control of antral and pyloric electrical activity in the rabbit

The effects of section and stimulation of the sympathetic nerve trunk on gastric motility were investigated in conscious and decorticate rabbits. In conscious animals after section of the abdominal splanchnic nerve, rhythm of antral and pyloric bursts was enhanced, becoming more regular, and the period of arrest of the rhythmic bursts, which was usually observed at the end of inflation of the antrum in intact rabbits, was shortened to 33.6 +/- 4.0 s from 112.2 +/- 14.6 s observed before the sympathetic nerve transection. Adrenergic agonists, phenylephrine (100 micrograms/kg), clonidine (5 micrograms/kg) and salbutamol (1 mg/kg) inhibited antral and pyloric activity. In decorticate rabbits the major effect of stimulation of the peripheral or the central end of the thoracic sympathetic trunk was inhibition; this was seen both with the spontaneous and vagally induced e.m.g. activity of the antrum and pylorus. Inhibition induced by stimulation of sympathetic efferents was abolished by beta-blocking agents and that induced by stimulation of the sympathetic afferents disappeared after alpha-adrenergic block. Significance of a dual control of the gastric motility by the sympathetic nerve was discussed.