Pancreatic duct cells secrete HCO3(-) ions into a HCO3(-)-rich luminal fluid (~140 mmol/L in human) against at least a 6-fold concentration gradient. Candidate mechanisms for HCO3(-) transport across the apical membrane include Cl(-)-HCO3(-)exchange by an SLC26 anion transporter and diffusion via the HCO3(-) conductance of cystic fibrosis transmembrane conductance regulator (CFTR). Members of the SLC26 family are known to mediate Cl(-)-HCO3(-) exchange across the apical membrane of other epithelia and both SLC26A6 and SLC26A3 have been detected in pancreatic ducts. Co-expression studies have also revealed that murine slc26a6 and slc26a3 physically interact with CFTR through the STAS domain of slc26 and the R domain of CFTR, resulting in mutually enhanced activity. Other studies have indicated that these exchangers are electrogenic: slc26a6 mediating 1Cl(-)-2HCO3(-) exchange and slc26a3 mediating 2Cl(-)-1HCO3(-) exchange. Recent experiments using isolated pancreatic ducts from slc26a6(-)/(-) mice suggest that slc26a6 mediates most of the Cl(-)-dependent secretion of HCO3(-) across the apical membrane in the mouse and the data are consistent with the reported electrogenicity of slc26a6. However, the role of SLC26A6 in human pancreatic HCO3(-) secretion is less clear because human ducts are capable of secreting much higher concentrations of HCO3(-). The role of SLC26A6 must now be evaluated in a species such as the guinea pig which, like the human, is capable of secreting HCO3(-) at a concentration of ~140 mmol/L. From existing guinea pig data we calculate that a 1Cl(-)-2HCO3(-) exchanger such as slc26a6 would be unable to secrete HCO3(-) against such a steep gradient. On the other hand, the HCO3(-) conductance of CFTR could theoretically support secretion of HCO3(-) to a much higher concentrations. CFTR may therefore play a more important role than SLC26A6 in HCO3(-) secretion by the guinea pig and human pancreas.
Animals ; Bicarbonates ; metabolism ; Chloride-Bicarbonate Antiporters ; physiology ; Cystic Fibrosis Transmembrane Conductance Regulator ; physiology ; Guinea Pigs ; Humans ; Membrane Transport Proteins ; physiology ; Mice ; Pancreatic Ducts ; cytology ; secretion

1. 5-HT inhibits spontaneous fluid secretion as well as stimulated secretion with secretin (cAMP mediated) or ACh (Ca2+ mediated) in the isolated guinea pig pancreatic ducts. 2. The inhibitory effect of 5-HT is reversible and is dependent on the concentration in the range 0.01-0.1 microM, which is much lower than those that affect intestinal motility and secretion. 3. The 5-HT3 receptor in duct cells appears to mediate the inhibitory effect of 5-HT. 4. [Ca2+]i is unlikely to mediate the inhibitory effect of 5-HT.
5-Methoxytryptamine/pharmacology ; Acetylcholine/pharmacology ; Animal ; Calcium/metabolism ; Guinea Pigs ; Pancreatic Ducts/metabolism* ; Pancreatic Ducts/drug effects ; Secretin/pharmacology ; Serotonin/pharmacology ; Serotonin/metabolism* ; Serotonin/analogs & derivatives* ; Vasodilator Agents/pharmacology

No abstract available.
Animal ; Bicarbonates/metabolism* ; Biological Transport/physiology ; Pancreatic Ducts/metabolism* ; Perfusion

Purpose: Gastric neoplasia is a common manifestation of familial adenomatous polyposis (FAP). This study aimed to elucidate the clinical characteristics, endoscopic features including fundic gland polyposis (FGPsis), and treatment outcomes of gastric neoplasms (GNs) in patients with FAP. Materials and Methods: A total of 35 patients diagnosed with FAP, including nine patients from four pedigrees who underwent esophagogastroduodenoscopy (EGD), were investigated regarding patient characteristics, GN morphology, and treatment outcomes. Results: Twenty-one patients (60.0%) had 38 GNs; 33 (86.8%) and 5 (13.2%) were histologically diagnosed with adenocarcinoma and adenoma, respectively. There were no specific patient characteristics related to GNs.Nodule-type GNs were more prevalent in patients with FGP than without (52.2% vs. 0.0%, P=0.002) in the upper body of the stomach. Conversely, depressed-type GNs were fewer in patients with FGPsis than in those without (13.0% vs. 73.3%, P<0.001). Slightly elevated-type GNs were observed in both groups (34.8% vs. 20.0%, P=0.538). Even within pedigrees, the background gastric mucosa and types of GNs varied. In total, 24 GNs were treated with endoscopic submucosal dissection (ESD) and eight with endoscopic mucosal resection (EMR). EMR was selected for GNs with FGPsis because of the technical difficulty of ESD, resulting in a lower en bloc resection rate (62.5% vs. 100%, P=0.014). Conclusions Our study indicates the necessity of routine EGD surveillance in patients diagnosed with FAP. Notably, the morphology and location of GNs differed between patients with and without FGPsis. Endoscopic treatment and outcomes require more attention in cases of FGPsis.