5-Hydroxytryptamine (serotonin, 5-HT) is a hormone and neurotransmitter regulating gastrointestinal functions. 5-HT receptors are widely distributed in gastrointestinal mucosa and the enteric nervous system. Duodenal acidification stimulates not only the release of both 5-HT and secretin but also pancreatic exocrine secretion. We investigated the effect of 5-HT receptor antagonists on the relea...

Graded doses of 0-1, 0-3, 0-9, and 2-7 clinical units/kg/h of pure synthetic secretin were infused over 60 minute periods in six healthy volunteers. Duodenal bicarbonate output and pH were recorded and plasma secretin and motilin levels were measured by radioimmunoassay. During the infusions plasma motilin fell in a dose dependent manner to a nadir of 35%. This fall was linearly correlated with...

The rate of gastric secretion probably depends upon a balance between secretory and inhibitory stimuli; increase of the former or decrease of the latter may lead to excessive acid production (Thompson, 1962). As a possible cause of duodenal ulcer more attention has hitherto been given to increased excitatory than to impaired inhibitory mechanisms. Inhibitory processes originating in the duodenu...

Luminal acidification provides the strongest physiological stimulus for duodenal HCO3- secretion. Various neurohumoral mechanisms are believed to play a role in acid-stimulated HCO3- secretion. Previous studies in the rat and human duodenum have shown that guanylin and Escherichia coli heat-stable toxin, both ligands of the transmembrane guanylyl cyclase receptor [guanylate cyclase C (GC-C)], a...

Although early studies attributed an important role to acid in the pathogenesis of duodenal ulcer pain, recent reports are conflicting. The aim of the present study is to determine whether direct acidification of the duodenal ulcer crater in symptomatic patients reproduces ucler pain. Patients with endoscopically diagnosed duodenal ulcers were studied. No premedication or sedation was given. A ...

PRESHAW, R. M., A. R. COOKE, AND M. I. GROSSMAN. Quantitative aspects of response of canine pancreas to duodenal acid&ation. Am. J. Physiol. 2 IO(~) : 629-634. I g66.-The pancreatic response to the introduction of hydrochloric acid into the duodenum at various rates was studied in conscious dogs. The flow rate of pancreatic secretion and the bicarbonate output were found to be related to the am...

To investigate the role of the mucus-bicarbonate barrier in the prevention of duodenal ulcer recurrence, duodenal mucosal neutralizing capacity and mucosal prostaglandin (PG) synthesis were examined in 5 normal controls (NC) and 12 duodenal ulcer (DU) patients. DU patients were divided into non-recurrent (NR,7) and recurrent (R,5) groups based on endoscopic follow-up study. The recovery time (R...

Secretin is an enterogastrone that inhibits gastric acid secretion and motility. Recently, it was reported that secretin inhibited gastric emptying via a capsaicin (Cap)-sensitive vagal afferent pathway. However, a possible role of the sensory afferent pathway in secretin-inhibited acid secretion has not been clarified. We investigated whether or not the acid secretion suppressed by secretin is...

The endocrine cells of the human duodenal bulb were observed under the electron microscope in biopsy tissues taken by normal procedure and after luminal acidification. 1. The endocrine cells in this portion were found more frequently than in the lower part of the duodenum previously examined by our research group. 2. At least 9 types of endocrine cells were distinguished by their fine structure...

HCO(3)(-) secretion, which is believed to neutralize acid within the mucus gel, is the most studied duodenal defense mechanism. In general, HCO(3)(-) secretion rate and mucosal injury susceptibility correlate closely. Recent studies suggest that luminal acid can lower intracellular pH (pH(i)) of duodenal epithelial cells and that HCO(3)(-) secretion is unchanged during acid stress. Furthermore,...