The pylorus

Abstract

The pylorus controls the flow between a reservoir dedicated to mechanical and chemical digestion (the stomach) and a conduit dedicated to the absorption of nutrients (the intestines). The pylorus adjusts gastric outflow resistance to physiological needs. It allows the outflow of isotonic fluids yet selectively retains particles too large for delivery to the intestines and in concert with the antrum further processes them (gastric sieving). Unlike most gut sphincters, the pylorus, at least of man, maintains a patent lumen most of the time. It only intermittently becomes a tightly closed barrier that arrests all flow out of and into the stomach. The geometry of the pylorus changes dramatically from the relaxed open state to closure. Pyloric closure involves contraction of its proximal and distal muscle loops, and occlusion of its lumen by mucosal folds. Current studies that combine pressure recordings with imaging by magnetic resonance imaging or ultrasound and fluid-mechanical analysis shed new light on the role of the pylorus in gastric emptying and digestion. Much has been learned in recent years on the innervation of the normal pylorus particularly from studies on infantile hypertrophic stenosis, and attempts are being made to treat gastroparesis by interventions on the pylorus.

In Vitro Effects of Rabeprazole on Human Pylorus Tone

“…8,[11][12][13] Even if pyloric and antral motor activities were studied in detail; the effects of PPIs which are the mainstay of treatment of gastritis, gastric ulcer, and gastroesophageal reflux disease, on human pyloric tonus have not been investigated yet.…”

“…24 Duodenogastric reflux occurs just before pyloric closure, and hence, for much shorter episodes than gastroduodenal flow. 8 As a result, the cyclic contractions play an important role in the maintenance of the sequence of duodenogastric reflux and gastroduodenal flow. In our study, contraction frequencies and maximum contraction values had a trend of reduction, starting with the therapeutic doses of rabeprazole and the difference became significant with high doses.…”

“…8,[11][12][13] Hence, any factor, which could interfere the cyclic contractions of the pylorus and antrum, may increase the reflux or slow down gastric emptying. [8][9][10] The previous studies on gastroduodenal flow have suggested that PPIs not only decrease acid but also bile reflux, owing to its antisecretory effects. [14][15][16][17][18] In the present study, we aimed to reveal the in vitro effects of PPIs on the contraction of human pylorus muscle, independent from anti-acid and antisecretory effects.…”

“…In previous in vivo studies, it has been shown that physiological gastroduodenal flow and duodenogastric reflux occurs in a sequence and duodenogastric reflux occurs just before pyloric closure following gastroduodenal flow. [8][9][10] Thus, the suspected cause of duodenogastric reflux or delayed gastric emptying is discoordination between pyloric and antral motor activities. 8,[11][12][13] Hence, any factor, which could interfere the cyclic contractions of the pylorus and antrum, may increase the reflux or slow down gastric emptying.…”

“…[8][9][10] Thus, the suspected cause of duodenogastric reflux or delayed gastric emptying is discoordination between pyloric and antral motor activities. 8,[11][12][13] Hence, any factor, which could interfere the cyclic contractions of the pylorus and antrum, may increase the reflux or slow down gastric emptying. [8][9][10] The previous studies on gastroduodenal flow have suggested that PPIs not only decrease acid but also bile reflux, owing to its antisecretory effects.…”