Response of the electrical activity, motor activity and acid secretion of the human stomach to pentagastrin and histamine stimulation

Effect of dopamine on pentagastrin-stimulated gastric antral motility in dogs with gastric fistula

The purpose of the present study was to evaluate the effect of dopamine on gastric antral motility in conscious dogs with gastric fistula by using miniature strain-gauge transducers. Infusion of pentagastrin changed the contractile activity to a digestive state. Dopamine, an endogenous catecholamine, was used alone and in conjunction with selective blockade or adrenergic and dopaminergic receptors. The stimulated antral motility was inhibited by dopamine. The effect was significantly blocked by the peripherally acting dopaminergic blocker domperidone and by cis-flupenthixol, which blocks both peripheral and central dopaminergic receptors. The effect of dopamine was not significantly altered by the beta 1-adrenoceptor blocker practolol, the alpha-adrenoceptor blocker phentolamine, or the alpha + beta-adrenoceptor blocker labetalol. Consequently, this study indicates that dopamine acts on gastric antral motility through dopaminergic receptors. beta-Adrenergic receptors, which are active in the impairment of gastric acid secretion, seem not to be involved in the motility response.

Effect of histamine H2-receptor blockade on gastric emptying and serum gastrin in man

The effect of orally administered metiamide, a Histamine H2-receptor antagonist, on the rate of gastric emptying was assessed in 24 uncomplicated duodenal ulcer patients given a standard meal containing indium 113m D.T.P.A. chelate. Metiamide produced significant slowing of gastric emptying when compared with control studies performed on the same patients following oral administration of a placebo. In a further study the effect of metiamide on the serum gastrin response to a protein meal was assessed in seven healthy male volunteers. Paired experiments demonstrated that a significantly greater elevation of serum gastrin occurred after metiamide than after placebo. The delay in gastric emptying produced by metiamide may be mediated by an elevation of the serum gastrin concentration.

Electrical activity of gastrointestinal smooth muscle

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The effects of humoral agents on the myoelectrical activity of the terminal ileum

Electrical and motor activities of the terminal ileum have been recorded in 25 patients with a permanent ileostomy. Records made within a week of formation of the ileostomy show an increased motor activity which is significantly reduced after four weeks. Intravenous infusion of gastrin, 1 mug/kg-hr, was accompanied by a significant increase in action potentials and in the percentage motility. Conversely, secretin 1 unit/kg-hr was associated with a decrease in action potentials and in percentage motor activity.