Motor responses of the human alimentary tract to near-maximal infusions of pentagastrin.

Misiewicz, J. J.; Holdstock, Douglas; Waller, Sheila L.

doi:10.1136/gut.8.5.463

Cited by 60 publications

(26 citation statements)

References 22 publications

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“…These results did not agree with previous data on the gastric motility (Bennett 1965;Isenberg and Grossman 1969;Cameron et al 1970;Vizi et al 1973;Cutierrez et al 1974;Misiewicz et al 1976). For example, gastrin was reported to increase the motility of the human antral strip (Cameron et al 1970) and intact stomach of the dog (Isenberg and Grossman 1969).…”

contrasting

confidence: 64%

Inhibition of the electrical and mechanical activities of the intestinal smooth muscle by pentagastrin.

Ohkawa

1978

Tohoku J. Exp. Med.

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contrasting

confidence: 64%

Inhibition of the electrical and mechanical activities of the intestinal smooth muscle by pentagastrin.

Ohkawa

1978

Tohoku J. Exp. Med.

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“…Gastrin's effect on gastric emptying is even more complex. Since gastrin is known to increase antral motor activity (35) and inhibit pyloric contraction, we would predict an acceleration of gastric emptying. Quite the contrary, a diminution of gastric emptying has been reported (36,37).…”

Section: Discussionmentioning

confidence: 99%

The Hormonal Regulation of Pyloric Sphincter Function

Fisher¹,

Lipshutz²,

Cohen³

1973

J. Clin. Invest.

121

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A B S T R A C T The purpose of this study was to evaluate the hormonal control of pyloric sphincter function. Studies were performed on both pyloric circular muscle, in vitro, and the human pylorus, in vivo. Full dose-response curves to gastrin I, cholecystokinin, and secretin were constructed for the pyloric muscle of the opossum studied at its length of optimal tension development, Lo. Both cholecystokinin and secretin were potent agonists on the muscle but gastrin I gave no increase in muscle tension. The combination of cholecystokinin and secretin was additive at submaximal concentrations but potentiation of the maximal responses was not observed. Gastrin I produced a surmountable, competitive-like antagonism to the effect of cholecystokinin on the pyloric muscle. The octapeptide of cholecystokinin was a more potent agonist than the whole molecule of cholecystokinin on the pyloric muscle. In man, the pyloric pressure rose significantly during intravenous infusion of either cholecystokinin or secretin. The combination of maximal doses of both hormones did not show signficant potentiation. Gastrin I did not significantly increase pyloric pressure but did antagonize the pyloric response to duodenal acidification. These studies suggest that: (a) Both secretin and cholecystokinin augment pyloric sphincter pressure while gastrin I is an antagonist inhibiting their effects. (b) The hormonal responses of pyloric sphincter circular muscle, in vitro, can be correlated with human sphincter function, in vivo.

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“…Ca2+ was important for the genesis of the action potential. Bennett, Misiewicz & Waller, 1967; Misiewicz, Holdstock & Waller, 1967;Isenberg & Grossman, 1969;Jacoby & Marshall, cholinergic nerves in the gastric wall to release acetylcholine Bennett, 1965;Jacoby & Marshall, 1969; Vizi, Bertaccini, Impicciatore & Knoll, 1973). However, the manner in which acetylcholine initiates phasic, rhythmic, motor activity is not known.…”

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confidence: 99%

Mechanism of action of pentagastrin and acetylcholine on the longitudinal muscle of the canine antrum.

Szurszewski¹

1975

The Journal of Physiology

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SUMMARY1. Electrical and mechanical activities of the longitudinal muscle of the dog antrum were recorded with the double sucrose-gap technique.2. The muscle exhibited spontaneous action potentials which consisted of a spike-like potential which, after a brief and partial repolarization, was followed by a negative-going, plateau-type potential. In 97 % of the preparations, no tension changes were produced by spontaneous action potentials.3. Tetrodotoxin, atropine, alpha-and beta-adrenoceptor antagonists, and H1 and H2 receptor blocking agents had no effect on the action potential. It was concluded that the action potential was myogenic in origin.4. The mean frequency of the action potential at 37 + 05°C was 1 0/min + 006 (S.E. of mean, n = 92) and the mean duration 7 1 + 0-2 sec (S.E. ofmean,n = 11).5. Steady depolarizing current increased whereas hyperpolarizing current decreased the frequency of the action potential.6. Length-tension relations were studied. In twelve strips, the average resting, passive, tension at Lo was 570 mg. The active force of isometric contraction produced by acetylcholine increased with strip length up to a maximum, then decreased with further increases in length. There were no mechanical responses to pentagastrin. 7. Pentagastrin had two sites of action. On smooth muscle, it increased the frequency of the action potential in a dose dependent fashion. Threshold concentrations ranged from 2 x 10-14 to 10-11 M. The ED50 was 2 x 10-10 M. The maximum response, 5-4/min, was reached at 10-8 M. Pentagastrin also released acetylcholine from intramural cholinergic nerves.8. Pentagastrin reduced the amplitude and duration of the action potential.J. H. SZURSZEWSKI 9. Acetylcholine produced phasic contractions which were associated with action potentials. This was its primary action. Initially, however, it produced a transient membrane depolarization, an increase in tension and an increase in the frequency of the action potential. During these initial effects and for as long as acetylcholine was present in the bathing solution, acetylcholine increased the amplitude and duration of the action potential.10. When acetylcholine and pentagastrin were present together in the bathing solution, phasic contractions occurred at the frequency of the action potential. Under these conditions, an increase in the concentration of acetylcholine increased the force of contraction whereas an increase in the concentration of pentagastrin increased the frequency of contraction but reduced the force of contraction. The reduction was due to a decrease in amplitude and duration of the action potential.11. Ca2+ was important for the genesis of the action potential.

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Motor responses of the human alimentary tract to near-maximal infusions of pentagastrin.

Abstract: EDITORIAL COMMENT Near maximal infusions of pentagastrin were found to have no consistent effect upon motility except in the gastric antrum. The results suggest that gastrin is not directly concerned in the mediation of the gastro-colic reflex.

Cited by 60 publications

References 22 publications

Inhibition of the electrical and mechanical activities of the intestinal smooth muscle by pentagastrin.

Inhibition of the electrical and mechanical activities of the intestinal smooth muscle by pentagastrin.

The Hormonal Regulation of Pyloric Sphincter Function

Mechanism of action of pentagastrin and acetylcholine on the longitudinal muscle of the canine antrum.

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