Influence of the proximal small intestine on the gastric hypersecretion in pylorus-ligated rats

An explanation of gastric hypersecretion in the pylorus-ligated rat

The hypersecretion of gastric acid in the pylorus-ligated rat has been shown to be of vagal origin. The present series of experiments were performed to identify the stimulus. The pyloric sphincter was ligated in a series of Sprague Dawley rats. Along with pylorus ligation, various other surgical manipulations were performed. Intestinal obstruction by ligation approximately 20 cm aboral to the cecum reduced unstimulated gastric secretion in the pylorus-ligated rat. However, perfusion of the lower small intestine with bicarbonate (143 mEq/L) stimulated secretion. Perfusion with either saline or deoxycholic acid (20 mEq/L) did not alter secretion. This supports a role for bicarbonate in the hypersecretion of gastric acid in the pylorus-ligated rat. The reflex appears to involve the myenteric plexus, since section of the pylorus seemed to attenuate gastric secretion. Plasma from animals with pylorus ligation, either alone or with intestinal ligation, equally inhibited gastric secretion. This suggests that while some factor inhibiting gastric secretion may be present, it appears to be unrelated to pylorus ligation.

Synthesis, gastroprotective, antisecretory and anti-Helicobacter effect of N-[3-(3-(1-piperidinylmethyl) phenoxy)propyl]-hydroxyacetamide 2-hydroxypropane-1,2,3-tricarboxylate bismuth (3+) complex (MX1)-MX1

MX1 (N-[3-(3-(1-piperidinylmethyl)phenoxy)propyl]-hydroxyacetamide+ ++ 2-hydroxypropane-1,2,3-tricarboxylate bismuth (3+) complex) is a novel salt of the active metabolite of H2-antagonist roxatidine with a complex of bismuth with citric acid. In a model of ethanol-induced ulcers in male Wistar rats, both roxatidine and the bismuth salt reduced the number and the total length of lesions. Comparison of roxatidine and MX1 at equimolar doses of 160 mumol kg-1 showed a more potent cytoprotective effect of MX1. The potency of anti-secretory and antiacidic effects of MX1 was more than twice that of roxatidine on histamine-stimulated secretion in female Wistar pylorus-ligated rats. Microbiological tests with the reference bismuth preparation De-Nol showed prominent anti-Helicobacter properties of MX1 in-vitro. Both test compounds had similar range of MICs to Helicobacter pylori, from 4 to 64 microgram bismuth mL-1. The cytoprotective, antisecretory, anti-acidic and anti-Helicobacter properties of the new agent MX1 warrant further more extensive pharmacological and clinical trials.

Role of local motility changes in the pathogenesis of duodenal ulcers induced by cysteamine in rats

The possible role of local motility in the pathogenesis of duodenal ulcers was investigated in rats using cysteamine. Duodenal motor activity was measured as intraluminal pressure recordings by means of a balloon positioned in the proximal duodenum. Subcutaneous administration of cysteamine (100 mg/kg) produced two linear bandlike lesions in the proximal duodenum within 6 hr. This dose of cysteamine significantly increased gastric acid secretion in acute fistula rats, and decreased duodenal HCO3- secretion caused by acid. During this period, this agent inhibited gastric motility but did produce markedly enhanced contractions in the duodenum. The changes in duodenal motility appeared within 5-10 min and were dose-dependent for cysteamine (10-100 mg/kg). Pretreatment with subcutaneously administered atropine (10 mg/kg), 16,16-dmPGE2 (30 micrograms/kg) or dopamine (10 or 30 mg/kg) significantly reduced the development of duodenal lesions caused by cysteamine, the inhibition being 86.8%, 49.7%, 54.5% or 67.8%, respectively. In the presence of cysteamine, dopamine had minimal effect on both acid and HCO3- secretion, while atropine or 16,16-dmPGE2 markedly inhibited acid secretion or increased HCO3- secretion, respectively. The enhanced duodenal motility induced by cysteamine was blocked partially by atropine and only slightly by 16,16-dmPGE2. Dopamine showed a dose-dependent inhibition on the duodenal hypermotility following cysteamine, and at 30 mg/kg almost completely abolished the development of contractions. These results suggest that abnormal hypermotility in the duodenum may be partly involved in the pathogenesis of cysteamine-induced duodenal ulcers.