Pyloric mucosa

Catechol is oxidized by peroxidases to the reactive intermediate benzo-1,2-quinone, which binds to protein. The acute toxicity of catechol is relatively low. In humans, the irritant action of catechol can lead to dermatitis and other dermal lesions. Chronic oral treatment of rodents causes hyperplasia of the forestomach and pyloric mucosa. 

Furihata, C., Hatta, A. Matsushima, T. (1989) Inductions of ornithine decarboxylase and replicative DNA synthesis but not DNA single strand scission or unscheduled DNA synthesis in the pyloric mucosa of rat stomach by catechol. Jpn. J. Cancer Res., 80. 1052-1057... 

Administration of hydroquinone (0.5% in the diet) for 20 weeks did not induce hyperplasia or papillomatous lesions in the forestomach in Syrian golden hamsters (Hirose etal., 1986). In male Fischer 344 rats, oral administration of hydroquinone for eight weeks (0.8% in the diet) did not induce hyperplasia or DNA synthesis, as measured by BrdU-labelling index in the forestomach epithelium. No cell proliferation, increased DNA synthesis or increase in pepsinogen-isoenzyme-1-altered neoplastic foci was observed in the pyloric mucosa (Shibata et al., 1990). 

An excellent example of apphcation of the first step of this technique has been reported by Daisley (1961). The vitamin B12 content of oceanic waters cannot be determined at sea water salinity. A binding agent prepared from pig pyloric mucosa may be added to the sea water before filtration through a column of Sephadex suspended in distilled water. If the binding agent is present in excess, vitamin B12 will be quantitatively com-... 

The fundic mucosal extracts from peptic ulcer patients hydrolyze both these peptides more readily than do extracts from normal mucous membrane, although the activity curves vary from case to case (T23). Extracts from pyloric mucosa in peptic ulcer patients also have more peptidase activity than those of normals, especially in regard to glycylglycylglycine substrate. The pH of the maximal activity is higher here than in normals. Gastric juice of ulcer patients does not contain peptidase activity. 

In patients with carcinoma of the stomach, the fundic mucosa not involved in the cancer digests these two peptides more readily than extracts from the normal stomach (T21). This peptidase shows activity with two maxima one at pH 7.0-7.6, and another at pH 8.2-S.5. Similar to extracts from pyloric mucosa, extracts from mucosa of gastric cancer patients attack alanylglycine more readily than glycylglycylglycine (T23). 

U5. Uvnas, B., Some chemical properties of the gastric secretory excitant from the pyloric mucosa. Acta Physiol. Scand. 6, 117-122 (1943). 

Neither Pavlov nor any of his immediate students attempted to identify the nature of the chemical link between the pyloric mucosa and the oxyntic cells. 

Figure 6-3. A Priestley and Mann s isolated pyloric pouch and totally transplanted fundic pouch in a dog used to study release of gastrin from the pyloric mucosa. B pH in the totally transplanted pouch following a, injection of 5 ml of beef extract dissolved in N/10 HCI into the pyloric pouch, and following b, subcutaneous injection of histamine. (From Priestely JT, Mann FC. Gastric acidity with special reference to the pars pylorica and pyloric mucosa. Arch Surg 25 395-403, 1932. Copyright 1932, American Medical Association.)...

This mechanical stimulation of fundic and pyloric mucosa in the main pouch cannot be shown, under the conditions of these experiments, to cause liberation of a humoral agent of gastric secretion. 

In order to determine the site of origin of the hormone, Gregory and Ivy excised the pyloric portion of the main stomach and converted it into a pyloric pouch (Fig. 6-4). They provided no evidence that all pyloric mucosa had been removed from the main pouch. Ivy wrote ... 

I]n four experiments so far performed, in which the main fundic pouch was perfused with a solution of secretagogues, a response of free acid was obtained from both this pouch and the transplant. [T]he unmistakable secretion of free acid by both pouches shows that the presence in the main gastric pouch of the pyloric mucosa is not essential for either the local response of the main fundic pouch or the humoral response of the transplant to perfusion of this with a solution of secretagogues. 

Uvnas repeated Simon Komarov s extraction of a histamine-free gastrin from the pyloric mucosa, and Nils Emmelin found that the preparation was indeed his-... 

Sacks J, Ivy AC, Vandolah J. Isolation of histamine from the pyloric mucosa. Proc Soc Exp Biol Med 28 941-942, 1931 Sacks J, Ivy AC, Burgess JP, et al. Histamine as the hormone for gastric secreton. Am J Physiol 110 331-338, 1932. See also Gavin GE, McHenry EW, Wilson MJ. Histamine in canine gastric tissue. J Physiol Lond 79 234-238, 1933. 

Priestley JT, Mann FC. Gastric acidity with special reference to the pars pylorica and pyloric mucosa. Arch 25 395-403, 1932. 

Robertson CR, Langlois K, Martin CG, et al. Release of gastrin in response to bathing the pyloric mucosa with acetylcholine. Am J Physiol 163 27-33,1950. 

Solcia E, Vassallo G, Capella C. Endocrine cells in antro-pyloric mucosa of the stomach. Z Zellforsch 81 474-486, 1967 idem. Studies on the G cell of the pyloric mucosa, the probable site of gastrin secretion. Gut 10 379-388,1969 Solcia E, Capella C, Vassallo G, et al. Endocrine cells of the gastric mucosa. Int Rev Cytol 42 223-286, 1975. 

In a subsequent series of experiments, Pavlov made a pouch of the pyloric antrum in a dog that also had a gastric fistula and a gastroenterostomy. He noted that introduction of chemical substances, such as meat extract, into an isolated and either innervated or denervated pyloric pouch resulted in a flow of gastric juice from the fundus. Sadly, neither Pavlov nor any of his immediate students sought to identify the nature of the chemical messenger that linked the pyloric mucosa and the oxyntic cells. 

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