Myogenic Basis of Motility in the Pyloric Region of Human and Canine Stomachs

Abstract

In vitro gastric motility was investigated in 48 human and 16 canine stomachs by measuring the mechanical activity of isolated muscle strips under auxotonic conditions. For a precise regional differentiation, we recorded the mechanical activity of longitudinal and circular strips from fundus, corpus and antrum, as well as from circular preparations of the inner and outer layer of the pyloric sphincter and from the duodenum. The analysis showed that the anatomical division of the stomach into three distinct regions resulted physiologically in different patterns of contraction in vitro for each region. The fundus exhibited purely tonic spontaneous activity and a tonic contraction pattern after application of acetylcholine whereas the activity in the circular antrum was purely phasic. A combination of tonic and phasic contractions was found in the corpus and longitudinal antrum. A major difference in the basic spontaneous activity pattern was evident between man and dog. A gradient of intrinsic frequency in the stomach from proximal to distal was seen in the dog but not in man. A physiologically distinct area exists in the pyloric region of both species adjacent to the antrum and duodenum. The pyloric ring has its own spontaneous activity (minute-rhythm), reacts to the application of acetylcholine with relatively weak contractions and, unique to the dog, was delineated by histamine-induced maximal contractions. The results provide evidence that the pyloric ring is a distinct organ with specific functional characteristics in its cellular-myogenic structure.

Nicotine Decreases Blood Alcohol Concentrations in Adult Rats: A Phenomenon Potentially Related to Gastric Function

“…These findings support the hypothesis that a nicotine-mediated decrease in BACs is indeed related to gastric functions, possibly through nicotine's action on nicotinic acetylcholine receptors in the pylorus (Daniel, 1965;Ludtke et al, 1991;Mandrek and Kreis, 1992). The current experiments were not specifically designed to confirm that nicotine delayed gastric emptying in these subjects.…”

Regional differences of the effects of acetylcholine in the human gastric circular muscle

“…One study showed that the fundus exhibited purely tonic spontaneous activity and a tonic contraction pattern after application of acetylcholine whereas the activity in the circular antrum was purely phasic. In the same study, the corpus and longitudinal antrum demonstrated a combination of tonic and phasic contractions (8). Currently, the exact mechanism of different effect of acetylcholine in fundus, corpus, and antrum is unclear.…”

“…These regional variations in contractile behavior may be attributed to the intrinsic properties of gastric smooth muscle cells and differences in the distribution of interstitial cells of Cajal (ICC) that provide pacemaker activity and function as critical mediators in enteric motor activity (4,12). However, to date there have been only a few studies supporting regional specialization in the contractile behavior of the human stomach (8).…”

The ‘minute rhythm’ incidence in the ovine abomasal antrum and small intestine

“…It can be partially linked with the arrival of the pyloric waves transporting the digesta to the duodenal bulb towards the distal duodenum (Gregory et al, 1985;Fioramonti & Bueno, 1988;Houghton et al, 1988;Lüdtke et al, 1991). Efficient transport of acidified chyme through the gastroduodenal junction is desired to stimulate duodenal controlling mechanisms responsible for the intestinal phase of the gastroduodenal motility and secretion.…”