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Only few studies have been devoted to the actions of the renin-angiotensin system (RAS) in the human gastrointestinal tract. The present study was undertaken to elucidate the expression and action of RAS in the human esophageal mucosa. Mucosal specimens with normal histological appearance were obtained from healthy subjects undergoing endoscopy and from patients undergoing esophagectomy due to neoplasm. Gene and protein expressions of angiotensin II (Ang II) receptor type 1 ([AT.sub.1]) and type 2 ([AT.sub.2]) and angiotensin-converting enzyme (ACE) were analyzed. In vivo functionality in healthy volunteers was reflected by assessing transmucosal potential difference (PD). Ussing chamber technique was used to analyze the different effects of Ang II on its [AT.sub.1] and [AT.sub.2] receptors. Immunoreactivity to [AT.sub.1] and [AT.sub.2] was localized to stratum superficiale and spinosum in the epithelium. ACE, [AT.sub.1], and [AT.sub.2] were found in blood vessel walls. Transmucosal PD in vivo increased following administration of the [AT.sub.1] receptor antagonist candesartan. In Ussing preparations mean basal transmural PD was -6.4 mV, epithelial current ([I.sub.ep]) 34 [micro]A/[cm.sup.2], and epithelial resistance ([R.sub.ep]) 321 [ohms] x [cm.sup.2]. Serosal exposure to Ang II increased PD as a result of increased [I.sub.ep], whereas [R.sub.ep] was constant. Ang II given together with the selective [AT.sub.1]-receptor antagonist losartan, or [AT.sub.2] agonist C21 given alone, resulted in a similar effect. Ang II given in presence of the [AT.sub.2]-receptor antagonist PD123319 did not influence PD, but [I.sub.ep] decreased and [R.sub.ep] increased. In conclusion, Ang II receptors and ACE are expressed in the human esophageal epithelium. The results suggest that [AT.sub.2]-receptor stimulation increases epithelial ion transport, whereas the [AT.sub.1] receptor inhibits ion transport and increases [R.sub.ep]. potential difference; epithelial current; epithelial resistance doi: 10.1152/ajpgi.00255.2009.

A comparative study of the influence of gastrin effects on histamine release, histidine decarboxylase (HDC) activity and DNA synthesis in pure enterochromaffin-like (ECL) cells shows that gastrin and cholecystokinin octapeptide (CCK-8) stimulate the release of histamine within 5 min of incubation and the release is associated with the biphasic elevation of intracellular Ca2+. Stimulation of HDC activity by gastrin occurs after 60 min of incubation and increase in DNA synthesis by gastrin has an EC50 of 1.7 times 10 to the power of -12 M.

Abstract Background The role of the renin-angiotensin system in gastric physiology and disease has as yet been sparsely explored. The first aim of the study was to investigate the baseline presence and location of angiotensin II receptors (AT1R and AT2R) in the stomach of the Mongolian gerbil. A second aim was to elucidate whether the presence of H. pylori infection is associated with changes in the expression of these receptors. Methods H. pylori-negative and H. pylori-infected (strain SS1 or TN2GF4) male Mongolian gerbils were investigated. The stomachs were examined at six or 12 months after inoculation by the use of immunohistochemistry, western blot and microscopic morphometry. Results AT1R and AT2R were located in a variety of cells in the gerbil gastric wall, including a subpopulation of endocrine cells in the antral mucosa and inflammatory cells infiltrating H. pylori-infected stomachs. Gerbils infected with the SS1 strain showed a significantly increased antral AT1R protein expression and an increased number of infiltrating polymorphonuclear leucocytes (PMNs) at 12 months. The AT1R protein expression correlated with the number of PMNs and the antral expression of myeloperoxidase. Conclusions Angiotensin II receptors are present in a variety of cells in the gastric wall of the Mongolian gerbil. The results indicate an influence dependent on the H. pylori strain on the gastric AT1R expression and a relationship between gastric AT1R expression and mucosal PMNs infiltration.

An [H.sup.+]-[K.sup.+]-ATPase contributes to hydrogen secretion and potassium reabsorption by the rat and rabbit collecting ducts. Transport of these ions appears to be accomplished by one or both of two isoforms of the [H.sup.+]-[K.sup.+]-ATPase, HK [[Alpha].sub.1] and HK [[Alpha].sub.2], because both isoforms are found in the collecting ducts and transport of hydrogen and potassium is attenuated by exposure to inhibitors of these transport proteins. To evaluate whether an [H.sup.+]-[K.sup.+]-ATPase is present in the human kidney, immunohistochemical studies were performed using normal human renal tissue probed with antibodies directed against epitopes of three of the known isoforms of the [HK.sup.+]-[K.sup.+]-ATPase, HK [[Alpha].sub.1], HK [[Alpha].sub.2], and HK [[Alpha].sub.4], and the V-type [H.sup.+]-ATPase. Cortical and medullary tissue probed with antibodies against HK [[Alpha].sub.1] showed cytoplasmic staining of intercalated cells that was less intense than that observed in the parietal cells of normal rat stomach stained with the same antibody. Also, weak immunoreactivity was detected in principal cells of the human collecting ducts. Cortical and medullary tissue probed with antibodies directed against HK [[Alpha].sub.4] revealed weak, diffuse staining of intercalated cells of the collecting ducts and occasional light staining of principal cells. Cortical and medullary tissue probed with antibodies directed against the [H.sup.+]-ATPase revealed staining of intercalated cells of the collecting ducts and some cells of the proximal convoluted tubules. By contrast, no discernible staining was noted with the use of the antibody against HK [[Alpha.sub.2]. These data indicate that HK [[Alpha].sub.1] and HK [[Alpha].sub.4] are present in the collecting ducts of the human kidney. In this location, these isoforms might contribute to hydrogen and potassium transport by the kidney. renal hydrogen-potassium-adenosinetriphosphatase; hydrogen; potassium; immunohistochemistry

This study investigated the distribution of Pb, Cd, Cr, Fe, Cu and Zn in the whole tissues of oysters (Saccostrea cucullata) and mussels (Perna viridis) collected from the three river basins of the coastal area in Chanthaburi Province, Thailand. The heavy metal concentrations in oysters followed the order: Zn>Fe>Cu>Cd>Cr>Pb, whereas in the mussels it was: Fe>Zn>Cu>Cr>Cd>Pb. The concentrations of Cu and Zn in the oysters were higher than the permission standard, and the bioconcentration factor (BCF) study revealed the ability of the oysters to accumulate the heavy metals. The results of depuration found that Cu and Zn levels in both oysters and mussels were below the permission standard after the end of the process. The time of depuration was related to the levels of Cu and Zn with the higher r values and the relationship of the depuration study obtained from the results of multiple regression analysis. [ABSTRACT FROM AUTHOR]

The sediment samples from 24 stations in coastal area of Chanthaburi Province were collected during March 2012 to March 2013 and analyzed for heavy metal contents (Pb, Cd, Cr, Fe, Cu and Zn), pH, organic matters and grain sizes. The correlation analyses showed that heavy metal concentrations were affected by the content of organic matter and the size of clay particles. The evaluation of the quality of sediment was carried out using the geoaccumulation index (Igeo) and the enrichment factor (EF) as well as the comparison with those in the Thailand's sediment quality guideline (SQG) values. The results of the geoaccumulation index and the enrichment factor values of the heavy metals content in the sediments revealed that the study area was unpolluted and not enriched, respectively. The relationship between the heavy metals concentration and the organic matter, and the clay particle was proposed by using the multiple regression equations. [ABSTRACT FROM AUTHOR]

Objective. Components of the renin-angiotensin system (RAS) were recently discovered in the esophagus, which could be of interest in relation to gastroesophageal reflux disease (GERD). The present study was undertaken to confirm and further investigate the expression of RAS in healthy and refluxed exposed human esophageal mucosae. Methods. Esophageal biopsies were obtained from healthy subjects ( n = 34) and individuals with erosive reflux disease (ERD, n = 28). Evaluation of general morphology and histological signs of reflux as well as investigation of gene transcript, protein expression and localization of various RAS components using RT-PCR, ELISA, western blot and immunohistochemistry were performed. Physiological effects of the AT2R were investigated in Ussing chamber experiments. Results. The study confirmed histological signs of reflux in ERD and expression of ACE, AT1R, AT2R and CatD in all examined specimens. In addition, the main effector peptide AngII, the pro-hormone AGT, the Mas receptor and the angiotensin-forming enzymes renin, CMA, CatG and NEP were present. Individuals with reflux disease had higher transcription activity of ACE and AT1R, increased protein levels of AT2R and lower levels of MasR. AT2R stimulation increased the ion currents in healthy epithelium, whereas epithelium from individuals with reflux disease exhibited no significant response. Conclusions. The study demonstrated that a local RAS is present in the human esophageal epithelium. Some RAS components were significantly altered in individuals diagnosed with ERD suggesting involvement in the pathophysiology of GERD. [ABSTRACT FROM AUTHOR]