Pharmacological activities of t-amyloxy-carbonyl tryptophanyl-methionyl-asparatyl-phenylalanine amide

Inhibitory effect of DS-4574, a mast cell stabilizer with peptidoleukotriene receptor antagonism, on gastric acid secretion in rats

We examined the inhibitory effect of DS-4574 (6-(2-cyclohexylethyl)[1,3,4]thiadiazolo[3,2-alpha]-1,2,3- triazolo[4,5-d] pyrimidin-9(3H)-one), a mast cell stabilizer with peptidoleukotriene receptor antagonism, on gastric acid secretion stimulated by several secretagogues in rats. In anesthetized rats with acute gastric fistulas, DS-4574 (50 mg/kg, intraduodenal) significantly inhibited gastric acid secretion induced by both carbachol (50 micrograms/kg, s.c.) and pentagastrin (75 micrograms/kg, s.c.) but not by histamine (2.5 mg/kg, s.c.). In unanesthetized pylorus-ligated rats, DS-4574 (10 and 25 mg/kg, intraduodenal) markedly suppressed increases in gastric acid output and histamine leakage into the gastric juice produced by carbachol (0.1 mg/kg, s.c.) or pentagastrin (1 mg/kg, s.c.). When the relationship between acid output and histamine leakage elicited by carbachol and pentagastrin was assessed, there was a close correlation (r = 0.84) that was highly significant (P < 0.01). In the in vitro study with rat gastric tissues, DS-4574 (10(-7)-10(-5) M) had no effect on the K(+)-dependent ATPase activity or on aminopyrine uptake into mucosal preparations containing parietal cells stimulated by carbachol (10(-5) M), histamine (10(-4) M), or dibutyryl-cyclic AMP (10(-3) M). These results suggest that the effect of DS-4574 may be mediated by inhibition of endogenous histamine from histamine-storing cells in the stomach.

Gastric acid stimulating action of cysteamine in the rat

Cysteamine was previously found to produce duodenal ulcers in rats. In the present study, the effect of cysteamine on gastric secretion was studied. Cysteamine administered by a parenteral or intraduodenal route induced a marked and sustained increase in gastric secretion in conscious and in anesthetized rats. The response to cysteamine or its metabolite, cystamine, appeared gradually and the maximum response was observed in 2 or 3 hr after the administration. The response to cysteamine was completely inhibited by vagotomy and inhibited dose-dependently by atropine methylbromide or hexamethonium. Cysteamine stimulated gastric acid secretion in conscious rats with chronic gastric fistula but not in rats with denervated gastric pouch. Tissue histamine levels in the gastric mucosa, abdominal muscle and whole blood were not affected by cysteamine. These results suggest that a cholinergic mechanism is involved in the gastric secretion induced by cysteamine.