Gastrin

Temporal aspects of the pathophysiology of human ulcer disease

In this paper, a peptic ulcer is considered from the perspective that it is representative of a heterogeneous group of multifactorial determined or influenced disorders having a common pathomorphologic expression. This heterogeneity involves pathophysiological attributes, including both functional (including secretory and motility events and their respective driving mechanisms) and morphologic alterations that relate to mucosal resistance. Patients with duodenal ulcer (DU) have been observed to exhibit alterations, in comparison to normal subjects, in the circadian rhythm characteristics of several gastrointestinal functions. Prominent among these are altered amplitudes of several circadian-organized gastric variables, such as intragastric pH, gastrin, pepsinogen and gastric mitotic index. With respect to any given variable, a reduced group amplitude (a measure of one-half the peak-trough difference of a 24-hr rhythm) could signify an increased dispersion of acrophases (the location of the peak of a circadian rhythm along the 24-hr time scale) reflecting interindividual variation in synchronization schedules, sleep-wake patterns, or chronobiologic alterations. A reduced interindividual amplitude further supports the concept of the heterogeneity of peptic disease. A decrease in the intraindividual amplitude of certain gastric rhythms implies an altered temporal pattern over the 24 hr. This is consistent with the hypothesis of a decrease in the amount of time available for recovery of a given function or set of integrated functions, and hence, increased susceptibility to mucosal injury. Normal high-amplitude variation in gastrointestinal functioning over the 24 hr appears to be required for natural restoration of the gut.

Technetium pertechnetate scintigraphy to detect ectopic gastric mucosa in Meckel's diverticulum

Tc-pertechnetate scintigraphy was performed in 81 infants and children, clinically suspected to have Meckel's diverticulum with ectopic gastric mucosa. The predominant symptom was rectal bleeding and anemia. Twenty-two patients underwent laparotomy and 12 had Meckel's diverticulum with ectopic gastric mucosa. In operated patients the sensitivity of scintigraphy in detecting ectopic gastric mucosa was 0.75, the specificity 1.0 and the diagnostic accuracy 0.86; the diagnostic accuracy was estimated to 0.96 for the whole material. Histologic examination of the diverticula showed a smaller area of the ectopic mucosa in cases with negative scintigraphic findings. In addition, prominent fibrosis seemed to be a more consistent finding in cases with negative as opposed to those with positive scintigraphic findings. Presence of anemia may provide a guideline as to whether or not scintigraphy is indicated.

The interaction of choline esters, vagal stimulation and H2-receptor blockade on acid secretion in vitro

Choline esters, bethanechol and carbachol, and electrical field stimulation increased acid secretion in the mouse, isolated, lumen-perfused, stomach. Electrical field stimulation was apparently mediated by vagal nerve ending because treatment with either tetrodotoxin or atropine abolished the response. Using a 2 + 2 assay design, experiments with bethanechol showed that the H2-receptor antagonists metiamide and cimetidine (1 mM) were devoid of antimuscarinic activity. However, the effects of carbachol, which unlike bethanechol stimulates both muscarinic and nicotinic receptors, were significantly antagonised by metiamide (1 mM) at a concentration which was not anticholinergic. We conclude that there are cholinergic receptors separate from histamine H2-receptors on parietal cells. The effects of vagal stimulation in this preparation however, are apparently mediated by histamine release. These results support the "two-cell hypothesis' where vagal nerve endings synapse with the parietal cell.

Thyrocalcitonin: stimulation of secretion by pentagastrin

Administration of a small dose of pentagastrin, a synthetic pentapeptide containing the biologically active portion of the native hormone gastrin, results in a marked, rapid, transitory increase in thyrocalcitonin secretion in the pig. Gastrin or a related gastrointestinal peptide may be important in the physiological secretion of thyrocalcitonin, such as that which occurs when calcium salts are introduced into the gastrointestinal tract.