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The morphology of the small intestinal mucosa is reflected by the degree of stimuli. Previous studies have come to different conclusion about whether the mucosa is equally symmetrical. The aim of the study is to investigate whether there are structural differences in the mesenteric versus antimesenteric mucosa in mice, rats, and humans. Jejunal biopsies from mice and rats were saved. Samples from human small intestine were obtained from patients undergoing Roux-en-Y gastric bypass surgery. Fixed samples were used to morphologically evaluate villus height and enlargement factor due to villi. The number of goblet cells, mast cells, enteroendocrine cells, and Paneth cells were histologically analyzed in the villus structure. Cell turnover was analyzed by Ki-67 staining. There was a significant increased villi height and villus enlargement factor antimesenterically in mice, rats, and human small intestines. The distribution of goblet cells, mast cells, and Paneth cells were equal while the number of enteroendocrine cells was increased antimesenteric in the human samples. The crypt mitotic activity was almost 20% higher in the antimesenteric part of jejunum. In summary we found longer villi, greater surface enlargement, and increased number of enteroendocrine cells as well as increased cell turnover antimesenterically. These differences may be of importance in understanding normal gastrointestinal physiology in health and disease., (© 2022 The Authors. Physiological Reports published by Wiley Periodicals LLC on behalf of The Physiological Society and the American Physiological Society.)

Background and Aims: The conditions for jejunal glucose absorption in healthy subjects have not been thoroughly studied. In this study we investigated differences in the jejunal villi enlargement factor, as well as ultrastructural aspects of the surface enterocytes and mitochondria, comparing 2 weeks of high-carbohydrate (HCD) versus high-fat diets (HFD). We also measured the ketogenesis rate-limiting enzyme 3-hydroxy-3-methylglutaryl-CoA synthase (HMGCS2) in relation to jejunal mitochondria., Methods: A single-centre, randomized, unblinded crossover study in 15 healthy volunteers ingesting strictly controlled equicaloric diets (either HCD or HFD), with 60% energy from the respective source. An enteroscopy was carried out after 2 weeks of each diet and jejunal mucosal biopsies were acquired. Conventional histology, immunofluorescent staining, transmission electron microscopy and confocal microscopy were used., Results: The villi did not demonstrate any change in the epithelial enlargement factor. Despite an increased mitosis, there were no changes in apoptotic indices. However, the ultrastructural analysis demonstrated a significant increase in the enlargement factor at the bases of the villi. The mitochondria demonstrated increased amounts of cristae after the HFD. The confocal microscopy revealed increased HMGCS2 per mitochondrial marker at the top of the villi after the HFD compared to the HCD., Conclusion: There is a morphometric adaption in the jejunal mucosa following the 2-week diets, not only on a histological level, but rather on the ultrastructural level. This study supports the notion that mitochondrial HMGCS2 is regulated by the fat content of the diet and is involved in the expression of monosaccharide transporters.

The villi of human jejunum vary in size and shape during different functional conditions. In the base the lamina propria is isotonic with blood, in the tip hyperosmotic. Here we study electrophysiological and morphological effects of incubation in hypotonic, isotonic, or hypertonic solutions, and to test various isotonic fixatives for microscopy. Samples of jejunal mucosae, obtained during surgery in obese patients, were studied in Ussing chambers where electrical parameters were registered during incubation in Krebs solution at various osmolarities, and during fixation in formaldehyde, glutaraldehyde, or osmium tetroxide (OsO 4 ). The same fixatives were used for other jejunal specimens that were fixed directly for light microscopy. Morphometry was carried out to determine size and height of villi, proportion of lamina propria, and surface enlargement due to villi. Ussing chamber incubation in fluids with low osmolarity resulted in increased electrical resistance and epithelial swelling. Opposite results were obtained at high osmolality. Fixation was faster in formaldehyde than in glutaraldehyde or OsO 4 . In biopsies processed directly for light microscopy the proportions of lamina propria of the mucosa, and of lamina propria of villi, were significantly larger in biopsies fixed in formaldehyde than after fixation in glutaraldehyde or OsO 4 . The villus tips sometimes ended with a bleb with prominent spaces between the epithelial cells. In summary, jejunal villi swell in vitro when exposed to hypotonic solutions, and shrink in hypertonic solutions. Much of the morphological changes occurring during fixation can be related to the physiological hyperosmolar milieu in villus tips., (© 2018 Wiley Periodicals, Inc.)

Objective: Barrett's esophagus (BE) is a risk factor for esophageal adenocarcinoma. In addition to its classical endocrine character known for hemodynamic regulation, the renin-angiotensin system (RAS) can be associated with inflammation, wound healing, and cancer. The aim of this study was to explore a potential expression of the RAS in BE, with or without the presence of dysplasia., Material and Methods: Biopsy material was prepared for western blotting and immunohistochemistry. Non-BE patients (controls) were compared with BE patients regarding RAS in the squamous epithelium. In the columnar BE mucosa, RAS expression was studied in patients with and without dysplasia. Key components of the 'classical' RAS were assessed: the angiotensin-converting enzyme (ACE) and the angiotensin II subtype 1 and 2 receptors (AT1R and AT2R)., Results: The presence of RAS factors was confirmed in the esophageal mucosa of both control and BE patients. ACE protein expression was 48% lower (p = 0.001) whereas AT1R was 45% higher (p = 0.039) in the squamous epithelium of BE patients compared to epithelia from non-BE controls. In the metaplastic intestinal-like epithelium, AT1R expression was 37% higher in BE patients with confirmed dysplasia than in patients without dysplasia (p = 0.009). Immunohistochemistry showed an altered distribution of RAS proteins in BE patients with dysplasia., Conclusions: The differential RAS expression observed may prove to be useful as a biomarker or a pharmaceutical target.

Background: According to textbooks, the human gut mucosa measures 260-300 m(2), that is, in the order of a tennis court. However, the quantitative data are incomplete and sometimes conflicting., Objectives: To review the literature regarding the mucosal surface area of the human digestive tract; to collect morphometric data from the parts of the gut where such data are missing; and to recalculate the mucosal surface area of the intestine in man., Methods: With focus on the intestine, we carried out morphometry by light and electron microscopy on biopsies from healthy adult volunteers or patients with endoscopically normal mucosae., Results: Literature review of intubation or radiological methods indicates an oroanal length of ∼5 m, two-third of which refers to the small intestine. However, there is a considerable variation between individuals. The inner diameter of the small intestine averages 2.5 cm and that of the large intestine averages 4.8 cm. The mucosa of the small intestine is enlarged ∼1.6 times by the plicae circulares. Morphometric data obtained by light and electron microscopy of biopsies demonstrate that villi and microvilli together amplify the small intestinal surface area by 60-120 times. Surface amplification due to microvilli in the colon is ∼6.5 times. The mean total mucosal surface of the digestive tract interior averages ∼32 m(2), of which about 2 m(2) refers to the large intestine., Conclusion: The total area of the human adult gut mucosa is not in the order of tennis lawn, rather is that of half a badminton court.

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 The endocrine cells of the gastrointestinal (GI) tract and the pancreas, referred to as the enteroendocrine cells, secrete a large variety of peptides and amines that regulate functions of the digestive tract itself and of distant organs. Taken together, the enteroendocrine cells form the largest system of endocrine cells in the body, presently comprising 16 cell types. Many of them have been named after letters of the alphabet, but the names are only occasionally related to morphological or functional characteristics of the cell. In this review of the normal, adult, mammalian enteroendocrine cells, we summarize synonyms, functions, locations, structure, stored hormones/amines, receptors, and other cellular expressions. We propose that the enteroendocrine cells should be renamed after their most well-known hormone/amine and, when applicable, their anatomical location, with opportunities for future revisions.

Introduction: The aim of the present study was to map the distribution of representative protein components of the renin-angiotensin system (RAS) in the human gastric mucosa., Materials and Methods: Biopsies from the antral and corporal mucosa of healthy Helicobacter pylori negative and positive volunteers were assessed by histology, Western blot and immunohistochemistry for angiotensin II subtype 1 and 2 receptors (AT1R, AT2R) and other RAS components (angiotensinogen, renin, angiotensin converting enzyme, and neprilysin). Mucosal levels of myeloperoxidase (MPO) served as a protein marker of neutrophil infiltration., Results: AT1R and AT2R were located in a variety of cells in the human gastric mucosa, including AT1R on a subpopulation of endocrine cells in the antral mucosa. Angiotensinogen and renin were expressed by resident mesenchymal cells in lamina propria. All investigated RAS components were found in vascular endothelial cells. The AT1R protein expression was 3-4 times higher in the gastric mucosa of H. pylori positive subjects compared to the gastric mucosa of H. pylori negative subjects (p < 0.05). Gastric mucosal AT1R protein expression correlated positively with neutrophil infiltration (r = 0.7, p < 0.05)., Conclusions: Protein components of RAS are present in the human gastric mucosa. The results suggest an angiotensin II mediated impact on mucosal epithelial functions, antral endocrine properties, microvascular permeability, and gastric inflammation.

Aims: Roux-en-Y gastric bypass surgery is the most efficient treatment of morbid obesity, but the mechanisms of action are still poorly understood. The aim of this study was to explore the Roux-limb mucosa after gastric bypass surgery, focusing upon basic morphology and inflammation., Methods and Results: Jejunal mucosal samples from the Roux-limb were gathered from eight patients at time of surgery and 6-8 months postsurgery. Histological evaluation of inflammation and morphometric investigations were performed, cell proliferation was assessed using immunohistochemistry and inflammatory markers and angiotensin (Ang) II receptors were detected using Western blot. Cell proliferation increased and villous surface area decreased in the Roux-limb mucosa but no signs of active inflammation were observed after surgery. Protein analyses showed increased levels of nicotinamide adenine dinucleotide phosphate (NADPH)-oxidase, myeloperoxidase (MPO) and the Ang II type 1(AT(1)) receptor after surgery, whereas the levels of inducible nitric oxide synthase (iNOS), nitrotyrosine and the Ang II type 2(AT(2)) receptor remained constant., Conclusion: These results indicate that the phenotype of the jejunal mucosa changes once exposed to undigested food and the increased microbial load in the Roux-limb after surgery., (© 2010 Blackwell Publishing Limited.)

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.

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(1)) and type 2 (AT(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(1) and AT(2) receptors. Immunoreactivity to AT(1) and AT(2) was localized to stratum superficiale and spinosum in the epithelium. ACE, AT(1), and AT(2) were found in blood vessel walls. Transmucosal PD in vivo increased following administration of the AT(1) receptor antagonist candesartan. In Ussing preparations mean basal transmural PD was -6.4 mV, epithelial current (I(ep)) 34 muA/cm(2), and epithelial resistance (R(ep)) 321 Omega.cm(2). Serosal exposure to Ang II increased PD as a result of increased I(ep), whereas R(ep) was constant. Ang II given together with the selective AT(1)-receptor antagonist losartan, or AT(2) agonist C21 given alone, resulted in a similar effect. Ang II given in presence of the AT(2)-receptor antagonist PD123319 did not influence PD, but I(ep) decreased and R(ep) increased. In conclusion, Ang II receptors and ACE are expressed in the human esophageal epithelium. The results suggest that AT(2)-receptor stimulation increases epithelial ion transport, whereas the AT(1) receptor inhibits ion transport and increases R(ep).

Background & Aims: Angiotensin II is a potent activator of smooth muscles but has not been much investigated with regard to gastrointestinal motor activity. This study explores expression of the renin-angiotensin system (RAS) in human esophageal musculature and actions by Angiotensin II both in vitro and in vivo., Methods: Muscular specimens of esophageal body and lower esophageal sphincter were obtained from patients undergoing resection as a result of mucosal neoplasm. Healthy volunteers participated in functional examinations of esophageal motility assessed by high-resolution manometry and multiple transmucosal potential-difference measurements., Results: Gene transcripts of key components of RAS were found in the esophageal musculature. Immunohistochemistry revealed a distinct staining for Angiotensin II type 1 (AT(1)) receptors in the muscular bundles and blood-vessel walls, whereas Angiotensin II type 2 receptors were confined to blood vessels only. Angiotensin II caused concentration-dependent contractions in vitro, which were inhibited by the AT(1) receptor antagonist losartan but not by the Angiotensin II type 2 receptor antagonist PD123319. Administration of the AT(1) receptor antagonist candesartan reduced the amplitude of swallow-induced peristaltic contractions and both the length and pressure amplitude of baseline high-pressure zone at the esophagogastric junction. Neither swallow-induced axial movements, nor the contraction after transient lower esophageal sphincter relaxations, were influenced by candesartan pretreatment., Conclusions: The study demonstrates a local RAS in the musculature of the distal esophagus and that Angiotensin II is a potent stimulator of esophageal contractions via the AT(1) receptor. The results suggest that Angiotensin II participates in the physiological control of the human esophageal motor activity.

Objective: Cell division is brisk in the ulcer margin and many of the new cells will migrate over and cover the ulcer bed. The aim of this study was to determine how agents that promote or delay gastric ulcer healing influence cell proliferation in the gastric epithelium., Material and Methods: Acetic acid ulcers were produced in the rat gastric corpus; non-ulcer rats served as controls. All rats were given a continuous infusion of (3)H-thymidine. Some rats were also given gastrin or indomethacin, or infected with Helicobacter pylori. The rats were killed after 1, 2, 6 or 13 days, and the ulcer margin and undamaged corpus were excised for determination of labeling index (LI) by autoradiography. Antrum, duodenum and colon were also studied. Silver grain counting was carried out in some groups., Results: LI in the ulcer margin grew exponentially, reaching 84% after 6 days; gastrin increased, and indomethacin decreased LI significantly. In 6-day ulcer rats that were given 3H-thymidine only during the first day LI was 5%, while in those given 3H-thymidine only during the last day LI was 27%. LI and silver grain counting results indicated that during the first 6 days of healing the epithelial cells in the ulcer margin divide twice. In the undamaged epithelium of the 1-day ulcer rats LI was

Background: During the healing of gastric ulcers, extensive changes take place in the structure and proportion of the parietal cells in the ulcer margin. We aimed to determine whether these changes are influenced by compounds or by procedures that may promote or delay gastric ulcer healing., Methods: Acetic acid ulcers were produced in the rat gastric corpus; control rats were non-operated or sham-operated. All rats were provided with an osmotic minipump releasing 3H-thymidine for determination of the labelling index (LI). The rats were given omeprazole, gastrin or indomethacin, infected with Helicobacter pylori, or subjected to anterior vagotomy. They were killed after 1, 2, 6 or 13 days, and the ulcer margin and undamaged corpus wall were excised for histology. The proportion of parietal cells was calculated in relation to the total number, and the total volume, of the epithelial cells., Results: The parietal cells averaged 16%-21% of the number and 30%-32% of the volume of the epithelial cells in the unoperated control rats, but considerably less in the ulcer margin. This reduction was partially prevented by indomethacin. In the undamaged, dorsal epithelium the parietal cells increased to 23%-26% of the number, and 41%-47% of the volume, of the epithelial cells, both in the ulcer rats and in the sham-operated rats. The LI of the parietal cells was 6% in the undamaged epithelium of the 13-day ulcer rats, but close to 0% in all other groups examined., Conclusion: Indomethacin prevents much of the loss of parietal cells in the ulcer margin. In the undamaged epithelium of the ulcer rats there is an increased proportion of parietal cells. The new parietal cells are not formed directly from dividing cells, but are probably recruited from existing precursor cells.

Background: This study investigates bradykinin and nitric oxide as potential mediators of AT2-receptor-stimulated duodenal mucosal alkaline secretion. Duodenal mucosal alkaline secretion was measured in methohexital- and alpha-chloralose-anaesthetised rats by means of in situ pH-stat titration. Immunohistochemistry and Western blot were used to identify the BK2 receptors., Results: The AT2 receptor agonist CGP42112A (0.1 microg kg(-1) min(-1)) administered intravenously increased the duodenal mucosal alkaline secretion by approximately 50 %. This increase was sensitive to the selective BK2 receptor blocker HOE140 (100 ng/kg i.v.), but not to luminal administration of the NOS blocker L-NAME (0.3 mM). Mean arterial pressure did not differ between groups during the procedures. Immunohistochemistry showed a distinct staining of the crypt epithelium and a moderate staining of basal cytoplasm in villus enterocytes., Conclusion: The results suggest that the AT2-receptor-stimulated alkaline secretion is mediated via BK2 receptors located in the duodenal cryptal mucosal epithelium.

Background: Hypergastrinaemia stimulates cell proliferation in the oesophageal epithelium of the rat. In the present study, we tested whether hypergastrinaemia also affected cell turnover time and structure of the oesophageal epithelium., Methods: Seventy-two female adult Sprague-Dawley rats, divided into 12 equal groups, were given 3H-thymidine by infusion/injection. Groups 1-6 were control rats, groups 7-9 were provided with a minipump releasing synthetic rat gastrin-17, and groups 10-12 were given injections of omeprazole twice daily. The rats in the control groups were killed after 1 h, and after 1, 6, 9, 17 or 25 days. The rats given gastrin or omeprazole were killed after 1, 6 or 9 days. Tissue samples of oesophagus were processed for light microscopic autoradiography and the labelling index (LI) was calculated. Morphometric data of the oesophageal epithelium were also obtained, as well as plasma gastrin concentrations., Results: LI in the control rats increased continuously up to 9 days when about 90% of the cells were labelled. Extrapolation indicates a mean cell turnover time of 10.4 +/- 0.58 days. Plasma gastrin levels were significantly elevated in the rats given gastrin or omeprazole. In these animals, average cell turnover times were reduced to 9.1 +/- 0.11 and 9.4 +/- 0.18 days, respectively, and the epithelium was almost 20% thinner than in the controls. Moreover, in the gastrin-treated rats the number of epithelial cells/mm was decreased by almost 20%., Conclusion: Hypergastrinaemia reduces cell turnover time in rat oesophageal epithelium. This is independent of stimulation of acid secretion. The concomitant epithelial hypotrophy may be explained by a premature shedding of the epithelial cells or by acceleration of cell maturation.

To study the kinetics of glutaraldehyde fixation, fresh rabbit liver cubes were immersed in 3% buffered 3H-glutaraldehyde for various periods of time. Following weighing and a brief rinse in water, the tissues were solubilized, and the radioactivity was measured in a scintillation counter. Binding of the isotope was half-maximal after approximately 4 h and a plateau was reached after approximately 20 h. We also investigated the reversibility of glutaraldehyde fixation. Fixed liver cubes were weighed and immersed in water for various periods of time, and after solubilization, the radioactivity was determined. After rinsing for 48 h, approximately 95% of the radioactivity was lost from the tissue specimens, indicating that fixation with glutaraldehyde is largely reversible. Light and electron microscopy of specimens rinsed for 1 and 48 h showed essentially similar morphology. Rinsing for 48 h restored some of the immunoreactivity that was absent after rinsing for only 1 h.

Parasympathomimetics or cholinesterase inhibitors taken orally may relieve dry-mouth symptoms, but this route of administration is often associated with adverse systemic reactions. In the present study, an animal model was worked out aimed at stimulating the submucosal glands and avoiding systemic effects. In the anesthetized ferret, saliva from the parotid, sublingual and submandibular glands was prevented from reaching the mouth. Vehicle or physostigmine was applied topically for 10 min on the buccal and labial mucosa on one side, while the other side served as a control. Fluid from each side was collected every 5 min Mean basal secretion was 0.17 mg 5 min(-1). The response to physostigmine 0.1% did not exceed that of the vehicle. At higher concentrations the responses lasted 80-120 min. Peak secretion was nine (0.25% physostigmine), 13 (0.5% physostigmine) and 40 (1% physostigmine) times higher than baseline. At 1% physostigmine, the secretion from the control side was elevated, and a small flow from the duct-cannulated parotid gland occurred, indicating systemic effects. Arterial blood pressure was well maintained. Additional observations on the duct-cannulated zygomatic gland showed that secretion from this gland increased already within the 10-min period of application of physostigmine to the overlying mucosa. The distance between the mucosa and the zygomatic gland was only about 1 mm. Physostigmine-induced secretion was abolished by atropine. Local gland stimulation may be an attractive alternative for the treatment of dry mouth.

A large number of the population, especially the elderly, suffers from dry mouth. The aim of the present investigation was to stimulate the minor salivary glands by the topical application of the cholinesterase inhibitor physostigmine. In eight healthy subjects. 100 microl of the substance, in the concentration interval 2-8 mg/ml, was applied locally to the inside of the lower lip for 1 min. In a separate study comprising 12 dry-mouth patients. 10 ml of 0.4 1.6 mg/ml physostigmine was administered as a mouth rinse solution for 2 min. Secretion from the labial glands. assessed using the Periotron method, increased in a dose-dependent manner in response to physostigmine in both groups. Average peak secretion exceeded baseline by more than 50% throughout the 30- to 45-min observation period; from 1.71 to 2.62 microl cm(-2) min(-1) among the healthy subjects and from 1.17 to 1.84 microl cm 2 min among the dry mouth patients. No systemic effects were registered as reflected by ECG, heart rate or blood pressure. It is assumed that intraorally applied physostigmine diffuses through the oral mucosa and acts by preserving acetylcholine released from the cholinergic, parasympathetic nerves that innervate the minor salivary glands. The topical application of physostigmine to the oral mucosa may, therefore, be an interesting approach for the treatment of dry mouth.

An H+-K+-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+-K+-ATPase, HKalpha(1) and HKalpha(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+-K+-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 H+-K+-ATPase , HKalpha(1), HKalpha(2), and HKalpha(4), and the V-type H+-ATPase. Cortical and medullary tissue probed with antibodies against HKalpha(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 HKalpha(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+-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 HKalpha(2). These data indicate that HKalpha(1) and HKalpha(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.

Background: Our understanding of the pathophysiology of gastro-oesophageal reflux disease (GERD) in man is limited. The aim of the present study was to establish a long-term (>1 year) animal model for reflux oesophagitis which would allow us to study various aspects of the development of chronic reflux oesophagitis., Methods: Myotomy was carried out in the gastro-oesophageal junction in eight cats; seven other cats were sham-operated. Before the operation, and every 2 months thereafter, oesophagoscopy was carried out, biopsies were taken for histology, and manometry was performed to determine the lower oesophageal sphincter pressure (LESP). The cats were killed 1 year after the operation., Results: The myotomy operation resulted in a significantly decreased LESP. In oesophageal biopsies from these cats, there was a varying degree of oesophagitis starting already 2 months after surgery. In six of the eight myotomized cats there was hyperplasia of the stratum basale, and cardiac type metaplasia was observed in two cats. The control cats showed no significant changes in LESP or in the histology of the oesophagus., Conclusions: In cats followed for more than a year, myotomy in the gastro-oesophageal junction results in reflux oesophagitis similar to that seen in patients with chronic gastro-oesophageal reflux.

The mucosa of the esophagus consists of stratified squamous epithelium that has a considerable resistance to injury. Intercellular glycoconjugates appear to constitute a major permeability barrier in the superficial portion of the esophageal mucosa. In the present study, we used a panel of lectins to investigate the differences in glycoconjugate production among different mammalian species. A battery of 12 lectins was used to study binding in sections from the esophagus of 6 mammalian species, including man. In general, the strongest staining was obtained in the stratum superficiale and the weakest staining in the stratum germinativum. In rabbit esophagus, exposure to pepsin/HCl produced a superficial damage to the epithelium, a considerable decrease in electrical resistance and a decreased staining of the esophageal epithelium with selected lectins. Pretreatment of the esophageal mucosa with sucrose octasulfate, a compound with protective properties, prevented, to some extent, the decrease in resistance and lectin staining.

The aim of the present study was to investigate responses from the gastric mucosa of rats during long-term H. pylori infection. Twenty-four Sprague-Dawley rats were inoculated with a mouse-adapted strain of human H. pylori (vacA+, cagA+), 16 uninfected rats served as controls. Three to six rats from each group were killed two weeks or two, six, or 12 months later. At sacrifice, blood was sampled and the gastric mucosa was taken for bacterial culture, histology, immunocytochemistry and in situ hybridization. H. pylori colonized the antrum in 23/24 inoculated rats; with time the density of bacteria increased. The inflammation in the antral mucosa was mild to moderate and was dominated by infiltration of lymphocytes and macrophages. Serum H. pylori-specific IgG2a was significantly increased in the infected rats. The frequency of epithelial cell apoptosis was significantly increased in the early months of infection. The mucosal expression of trefoil peptide mRNA remained unchanged. We conclude that after one year of H. pylori infection in rats, the mucosal responses were rather mild, indicating that the animals may adapt to the infection by mechanisms which remain to be identified.

In some species, including man and mouse, bile salt-stimulated lipase (BSSL) in milk catalyzes the hydrolysis of triacylglycerides into glycerol and free fatty acids, a reaction that is of particular importance during suckling. The enzyme is also secreted by the pancreas (referred to as carboxyl-ester hydrolase, CEH). We wished to localize sources and storage sites for BSSL/CEH in rats, in wild-type mice, and in transgenic mice producing recombinant human BSSL in milk. Immunoreactivity against several BSSL fragments was strong in the pancreatic acinar cells and moderate in the absorptive cells of the small intestine and in salivary duct cells of the mice, as well as in rats. Sections from lactating mammary glands of mouse, but not rat, also showed immunoreactivity for BSSL; the signal was strongest in the transgenic mice. Radioactive riboprobes for BSSL mRNA hybridized on sections of rat and mouse pancreatic acinar cells, and mouse mammary glands (both wild-type and transgenic). Using RT-PCR, it was possible to amplify BSSL mRNA from wild-type mouse pancreas and mammary gland, from rat submandibular glands, and, in a few cases, from rat liver. In transgenic mice, the BSSL mRNA was highly expressed only in lactating mammary gland, but could be detected in a few other organs as well.

Background: Our aim was to infect rats with Helicobacter pylori and to study the effects of the infection on the gastric mucosa in normal and in ulcer-operated rats., Methods: A mouse-adapted H. pylori (cagA-, VacA-) strain was inoculated into 23 rats. Another 20 uninfected rats served as controls. Two months later a gastric ulcer was induced in some rats. The animals were killed 3, 6, or 15 days after the ulcer operation. Tissues were taken for histology and for culture of H. pylori. Serum antibodies were determined., Results: All inoculated rats were infected by H. pylori after 2 months, mainly in the antrum. In these rats a mild to moderate chronic inflammation and a significantly increased frequency of apoptotic cells were observed in the antrum and in the ulcer margin, the ulcer healing was delayed, and the serum level of H. pylori-specific Ig was increased., Conclusions: H. pylori infection in rats was successful and was accompanied by a mild to moderate mucosal inflammation. Gastric ulcer healing was delayed in infected rats, probably due to the inflammation and the increased apoptosis in epithelium.

Background: Helicobacter pylori is associated with peptic ulcer disease. In the present study, the influence of VacA and CagA- H. pylori on gastric ulcer healing was studied in the rat., Methods: Twenty-four rats with acetic-acid-induced gastric ulcer were divided into two groups and given either vehicle (Brucella broth) or H. pylori suspension by gavage every 12 h for 7 days. The animals were killed 1 and 8 days after the last H. pylori gavage (i.e. 10 and 17 days after the induction of the ulcer). One hour before death, 3H-thymidine was given intraperitoneally. Tissue samples from the stomach (including the ulcer area) and the duodenum were processed for determination of labelling index and apoptotic cells., Results: Compared with the vehicle-treated controls, the ulcer area in H. pylori-inoculated rats was significantly larger, the epithelial apoptotic cells in the ulcer margin and intact corpus were more numerous, while the cell proliferation of gastroduodenal epithelium was slightly, but not significantly, increased by H. pylori gavage., Conclusion: Gastric ulcer healing was delayed after the inoculation of VacA- and CagA- H. pylori in the rat, possibly as a result of excess cell loss by apoptosis.

Gastrin/CCK-B receptors are involved in the regulation of several types of cells of the gastric mucosa, including the parietal cells, the ECL cells and the D cells. In this study, we aimed at localizing such receptors in the gastric mucosa. For this purpose, we prepared monospecific antibodies against two sequences of the canine gastrin/CCK-B receptor. Sections of formalin-fixed, paraffin-embedded corpus and antrum from dog and guinea-pig were immunostained with these antibodies. In parallel, sections were stained with antibodies against somatostatin. Staining with gastrin/CCK-B receptor antibodies was observed in a few, small epithelial cells in the bottom part of the corpus mucosa. Immunoreactive cells of the antral mucosa were structurally similar, but more frequent. The same cells also stained with somatostatin antibodies. In addition one of the gastrin/CCK-B antibodies reacted with canine submucosal smooth muscle cells. No staining was observed in sections exposed to antibodies that were pre-absorbed with the corresponding antigen. We conclude that gastrin/CCK-B receptors are present in D cells of the gastric mucosa and in submucosal smooth muscle cells.

Cholinergic stimulation of receptors in the oxyntic mucosa results in secretion of mucus, pepsinogen and hydrochloric acid. There has been speculation as to the cellular localization of these receptors in the mucosa and as to which subtype is present in the different cell types. In the present study, utilizing radioactive riboprobes for the M1 muscarinic receptor subtype, we carried out in situ hybridization to determine which cells of the gastric corpus transcribe mRNA for this receptor. The antisense M1 probe hybridized strongly on the zymogen cells and, to a lesser extent, on the surface mucous cells and the muscle layers. Control sections from brain also displayed specific hybridization.

During the healing of experimental gastric ulcers in the oxyntic mucosa, there is a dedifferentiation of the glands in the ulcer margin: previous studies have shown that the parietal cells lose their capacity to produce HCl, and mucous cells replace the zymogen cells. Primarily, we wished to investigate whether or not the glands of the ulcer margin transcribe mRNA for pepsinogen; secondly we also wanted to locate such transcription in other parts of the gastroduodenal epithelium. For this purpose, we first established the baseline for distribution of pepsinogen mRNA in normal rats. We then studied its location in the margin of ulcers in the corpus region after 1-15 days of healing. Formaldehyde-fixed paraffin sections were used for in situ hybridization of mRNA for pepsinogen C, utilizing radioactive riboprobes. The normal gastroduodenal mucosa showed widespread hybridization: the signal was particularly strong in the zymogen cells; weaker signals were obtained from the mucous neck cells, and the cells of the cardiac, antral, and Brunner glands. Specific hybridization was weak or absent in the ulcer margin during the entire period studied. It is concluded that the capacity to produce pepsinogen C is significantly reduced or absent in the gastric ulcer margin during the first 15 days of healing; this should reduce the risks of peptic attack on the delicate scar and margin tissues during ulcer healing.

We investigated if hypergastrinemia exerted any influence on the proliferation of gastroduodenal epithelium during the healing of ulcers in rats. A mucosal ulcer was induced in the corpus region of the stomach in three groups of rats, which were then given vehicle, omeprazole (400 mumol/kg/day), or gastrin-17 (60 nmol/kg/day) for three or six days. A fourth group of unoperated rats served as controls. One hour before killing, [3H]thymidine was injected. The ulcer margin and corresponding control tissues were excised and processed for light microscopic determination of epithelial labeling index (LI), mitotic index, and apoptotic index. LI was also determined in other parts of the gastroduodenal mucosa. Three and six days after the ulcer operation, the LI in the vehicle-treated ulcer rats was significantly increased in the ulcer margin and in the duodenum, in comparison with the intact controls. In the ulcer margin, the mitotic index was significantly increased, in parallel with the LI; the apoptotic index remained at the control level. The LI in the ulcer margin was increased further after administration of omeprazole or gastrin-17, which elevated the plasma gastrin levels by 5-15 times. It is concluded that hypergastrinemia may increase cell proliferation in the ulcer margin, which may accelerate the rate of healing.

Background: This study aimed at determining the turnover rate of parietal cells after inhibition of acid secretion., Methods: Rats were given omeprazole (80 mumol/kg) by gavage once daily or ranitidine (1200 mumol/kg) by osmotic minipump for 5 days. Control rats received saline only. All rats were also given 3H-thymidine by osmotic minipumps. The animals were killed, 5, 14, 28, or 56 days after the start of the 3H-thymidine infusion. After formaldehyde fixation by perfusion through the aorta, light microscopic autoradiography was carried out on plastic sections of the oxyntic mucosa to determine the labeling index of the parietal cells., Results: The average turnover rate in the control rats was calculated to be 0.61% per day, corresponding to a mean turnover time of 164 days. In the rats given inhibitors of acid secretion, the turnover rates did not differ significantly from those of the control group., Conclusion: Inhibition of gastric acid secretion did not significantly change the turnover rate of the parietal cells.

The hormone gastrin stimulates acid secretion by releasing histamine from gastric enterochromaffin-like (ECL) cells and induces ECL cell proliferation in vivo. This study uses a > 90% pure ECL cell preparation in culture to compare gastrin effects on histamine release, histidine decarboxylase (HDC) activity, and DNA synthesis. Gastrin and the cholecystokinin octapeptide (CCK-8, nonsulfated) induced histamine release from ECL cells (24-96 h of primary culture) within 5 min of incubation [concentration eliciting 50% of maximal response (EC50), 4 and 2 x 10(-11) M, respectively]. The CCK-B antagonist L-365,260 inhibited this effect [concentration inhibiting 50% of maximal response (IC50), 2 x 10(-8) M], whereas the CCK-A antagonist L-364,718 (10(-8) M) and the tyrosine kinase inhibitor genistein (10(-4) M) had no effect. Histamine release was associated with a biphasic elevation of intracellular Ca2+. Gastrin stimulated HDC activity two- to threefold after 60 min of incubation (EC50, 10(-10) M). Gastrin also increased DNA synthesis in ECL cells, with an EC50 of 1.7 x 10(-12) M as measured by the incorporation of 5-bromo-2'-deoxyuridine (BrdU). Positive nuclear immunostaining increased two- to threefold in up to 20% of ECL cells after 48-96 h of incubation. This effect was inhibited by L-365,260 (IC50, 5 x 10(-9) M) and by genistein (10(-4) M) but was not altered by L-364,718 (10(-8) M). The antisecretory drugs omeprazole, lansoprazole, and pantoprazole did not affect BrdU incorporation in isolated ECL cells. In conclusion, acute and chronic gastrin effects on the ECL cell are mediated via CCK-B receptors but differ in apparent receptor affinity and signal transduction pathways.

The H+,K(+)-ATPase member of the phosphorylating ion motive ATPases is composed of two subunits, a large alpha-subunit composed of about 1030 amino acids and a smaller beta-subunit consisting of about 290 amino acids. By biochemical and immunological methods both subunits have been found in high abundance in the gastric parietal cell. In the present study in situ hybridization was used for localizing and comparing concentrations of the mRNA for the two subunits in the gastric epithelium. For this purpose 3H-labelled probes were preferred. Hybridization was detected only in the parietal cells. The older parietal cells in the bottom of the mucosa gave a weaker hybridization signal than the younger parietal cells closer to the surface. The margin of experimental ulcers, where the parietal cells are of low differentiation, showed very weak, if any, hybridization. The differences observed in hybridization densities may reflect differences in mRNA synthesis or stability. It is conceivable that older parietal cells, as well as parietal cells of low differentiation, produce relatively small amounts of H+,K(+)-ATPase.

A parotid acinar degranulation of approximately 60 and 40% was observed in cats under pentobarbitone anaesthesia after a 90-min period of continuous stimulation of the parasympathetic auriculo-temporal nerve at 10 Hz in the absence and presence of atropine, respectively. Atropine completely abolished the large fluid response of the gland to the nerve stimulation. In the non-atropinized cats, bethanechol, infused into the carotid artery at a dose rate evoking a salivary flow similar to that in response to parasympathetic nerve stimulation, caused an acinar degranulation of approximately 25% and acinar vacuolation. Vasoactive intestinal peptide (VIP; 0.5 microgram kg-1 min-1 also infused into the carotid artery for 90 min) caused an acinar degranulation of the same magnitude as the parasympathomimetic drug but the peptide did not give rise to any fluid secretion or vacuole formation. The experiments were performed in the presence of alpha- and beta-adrenoceptor blockers. Thus, in parotid glands of the cat, producing no overt secretion of fluid, non-adrenergic, non-cholinergic (NANC) mechanisms may be at work causing exocytosis of the acinar granules. These mechanisms are also likely to contribute to the secretion of granules in response to parasympathetic nerve activity in the absence of blockade of the classical autonomic receptors.

1. Female adult rats were subjected to sympathetic denervation of the parotid glands by bilateral removal of the superior cervical ganglion 10-12 days before acute experiments. The sympathectomy was in some of the experimental groups combined with either bilateral adrenal medullectomy, treatment with the sensory neurotoxin capsaicin or parasympathetic denervation of the gland by cutting the auriculotemporal nerve. 2. Food but not water was withheld for 29-32 h before acute experiments. All animals were given an intraperitoneal injection of phentolamine (2 mg kg-1) and propranolol (1 mg kg-1) and, when appropriate, also atropine (1 mg kg-1). Then the experimental animals were fed their ordinary food of hard chow for 60-90 min. Thereafter, these animals and their non-fed controls were killed, and the parotid glands were removed and used for either morphometric assessment or measurement of amylase activity. 3. In the atropinized rats subjected to sympathectomy alone, eating reduced the numerical density of acinar secretory granules by 50% and the total activity of amylase by 55%; the corresponding figures were, when sympathectomy was combined with adrenal medullectomy, 51 and 63%. Also, in atropinized animals subjected to sympathectomy and capsaicin pretreatment, eating reduced the numerical density of acinar granules and the total amylase activity, in this case by 45 and 35%, respectively. 4. In the atropinized rats subjected to sympathectomy and parasympathectomy, eating caused no change in the numerical density of acinar granules but reduced the total amylase activity by 35%. 5. In the non-atropinized rats subjected to sympathectomy alone, eating reduced the numerical density of acinar granules by 22%, while there was no change in the total amylase activity. 6. In conclusion, eating evoked a reflex activation of the sympathectomized parotid gland that engaged non-adrenergic non-cholinergic receptors of the acinar cells. The present results give weight to a physiological role for non-adrenergic non-cholinergic parasympathetic mechanisms in salivary secretion under reflex conditions.

The hypothesis that intestinal fluid secretion is driven by Cl- has been tested by investigating the effects of NPPB (5-nitro-2-(3-phenyl-propylamino)-benzoate), a blocker of Cl- channels in nephrons, and the loop diuretic bumetanide, an inhibitor of the Na+, K+, 2Cl(-)-co-transporter. Both NPPB (IC50 (inhibitory concentration) approximately 100 microM) and bumetanide (IC50 approximately 2 microM) inhibited stimulated short-circuit current (Isc) in monolayers of a colonic cell line T84. NPPB also inhibited 36Cl- uptake by these cells, indicating that NPPB acts as a Cl- channel blocker in the T84 cells. NPPB (300 microM) and bumetanide (10 microM) abolished both stimulated Isc and Cl- secretion in isolated rat colonic mucosa. As judged by autoradiography, [3H]NPPB was found both in the crypts and at the surface after exposure of either side to the compound. In line with these results, NPPB and bumetanide reduced stimulated fluid secretion in everted colon sacs from the rat. In the anaesthetized rat model, neither bumetanide nor NPPB affected the net fluid transport. After luminal administration of [3H]NPPB to the rat, radioactivity was found mainly in the villus tips, whereas no labelling was found in the crypts. NPPB was bound to plasma protein (99%), and the inhibitory effects of both NPPB and bumetanide on Isc in T84 cells and fluid secretion in the colonic sacs decreased in the presence of albumin, again indicating that the compounds might not reach the in vivo target, or that the mechanism for fluid secretion in vivo may not be explained solely by the secretion of Cl-.

Background: In vivo studies have suggested an important role for gastric enterochromaffinlike (ECL) cells in mediating acid secretion. Direct evidence for this function is lacking and requires a preparation of highly purified ECL cells. This work investigates the possible role and mechanism of histamine release from the ECL cell in the peripheral regulation of acid secretion, using purified ECL cells from rat fundic mucosa., Methods: A combination of elutriation and density-gradient centrifugation was used to purify rat fundic ECL cells. Enrichment was determined by the presence of acidic vacuoles containing a V type adenosine triphosphatase, electron microscopy, immunostaining, and histamine content and release., Results: ECL cells were enriched at least 65-fold with respect to the fundic epithelium. Gastrin (EC50 0.2 nmol/L) and cholecystokinin octapeptide (nonsulfated, EC50 0.04 nmol/L) stimulated histamine release in a time- and dose-dependent manner, suggesting a CCK-B receptor subtype, confirmed by the inhibition of gastrin/CCK stimulation with the CCK-B antagonist L365,260. Somatostatin also inhibited gastrin-mediated histamine release. Single cell imaging showed that gastrin elevated intracellular cytosolic calcium concentration biphasically. Carbachol and the C kinase activator 120-tetradecanoylphorbol-13-acetate also stimulated histamine release. Epinephrine (blocked by propranolol), forskolin, and dibutyryl-5'-cyclic adenosine monophosphate were also effective, implicating a beta-adrenergic pathway. The H3 agonist R-alpha-methyl-histamine inhibited, whereas the H3-antagonist thioperamide potentiated gastrin/CCK stimulated histamine release., Conclusions: These in vitro results support a central role for the ECL cell in the peripheral regulation of gastric acid secretion.

The parietal cells, which are responsible for the production of gastric HCl acid, are uniquely equipped for high-gradient ion transport. Adequate energy is supplied by oxidative metabolism in the mitochondria, which occupy an exceptionally high proportion of the cytoplasmic volume. Another characteristic feature is the secretory canaliculi. These are tortuous small channels lined by microvilli which penetrate all parts of the cytoplasm and which expand during stimulation of secretion. The activity of the parietal cell is controlled by receptors for acetylcholine, histamine and gastrin on the basolateral cell membrane. Stimulation of these receptors modulates the levels of protein kinases in the cell and brings about the changes from resting to stimulated structure. A key role in the production of acid is played by the gastric acid pump, also known as the H+, K(+)-ATPase, which exports hydrogen ions in 1:1 exchange for potassium ions. This protein is a member of the P-type ATP-driven ion pumps and appears to be uniquely located in the parietal cell. The gastric acid pump is found in the tubulovesicular membranes of the resting cell and moves to the membrane lining the secretory canaliculus when acid secretion is stimulated. Functional acid secretion also requires the presence of KCl pathways in the secretory membrane in order to supply the acid pump with a source of potassium ions. For each hydrogen ion secreted across the secretory membrane, one bicarbonate ion is generated in the cytoplasm and is transported across the basolateral membrane in exchange for chloride. The movement of ions across the apical membrane is followed osmotically by water, resulting in the secretion of 160 mM HCl from the parietal cell.

Initiation of acid secretion in the gastric mucosa is accompanied by a morphological transformation in which the acid pump, the H+/K(+)-ATPase, translocates from a cytoplasmic vesicular location to the secretory surface lining the canaliculi. Associated with the morphological changes, activation of K+ and Cl- pathways are necessary to supply K+ to the extracytoplasmic face of the pump. Although the pump in the secretory membrane is known to secrete acid, it is not known whether activation of the KCl pathway occurs in the tubulovesicular membrane prior to the formation of the canaliculus, or when the pump is in the secretory membrane. The cellular site of activation of acid secretion in the rabbit gastric parietal cell was investigated using the covalent binding of [3H]omeprazole as a probe of acid secretion in rabbit gastric glands that were undergoing stimulation in vitro. This compound depends on an acidic environment for activation and covalent binding to the H+/K(+)-ATPase. Electron microscopic autoradiography showed that activation of the enzyme occurred only when it was present in the canalicular membrane and not when it was present in the cytoplasmic tubulovesicular membrane. Hence there is likely to be a physical separation of K+ and/or Cl- pathways from the ATPase in the resting cell, and stimulation of acid secretion is dependent on colocalization of these pathways in the canalicular membrane.

Biopsy specimens from the oxyntic mucosa were obtained on 210 occasions from 76 patients with the Zollinger-Ellison syndrome (ZES) before and during omeprazole treatment. One-micrometer sections were examined by light microscopy, and in 5% linear hyperplasia of endocrine cells was observed. Morphometry was carried out in 91 of the specimens and showed a significant increase of the mean endocrine cell density in comparison with both young, healthy subjects and patients suffering from active peptic ulcer disease (PUD). No metaplasia, dysplasia, or neoplasia was detected in patients with ZES, and the mean mucosal thickness and parietal cell density remained normal. The parietal cells often displayed endosome-like structures, and occasionally there were lingulate cytoplasmic projections into the gland lumen. Electron microscopic morphometry was carried out in specimens from nine patients with ZES and did not show any significant differences in the parietal cells in comparison with healthy subjects.

Parietal cells from rabbit gastric mucosa, enriched to greater than 90% purity, were used to study the effect of the H+,K(+)-ATPase inhibitor omeprazole on DNA in vitro. In this preparation, omeprazole undergoes acid-catalyzed conversion to its active form, the sulfenamide, which subsequently binds to luminal SH groups of the H+,K(+)-ATPase and thereby inhibits acid secretion. In the parietal cell fraction the S-phase inhibitor hydroxyurea (HU) decreased [3H]thymidine uptake by 40% as measured by liquid scintillation counting (LSC), presumably due to inhibition of scheduled DNA synthesis in contaminating stem cells. In the presence of HU, irradiation with ultraviolet light (UV) or treatment with the gastric carcinogen, 1-methyl-3-nitro-1-nitrosoguanidine (MNNG) increased [3H]thymidine uptake by a factor of 5. Autoradiography of isolated, stimulated parietal cells showed that UV irradiation and MNNG treatment increased the average number of silver grains over the nuclei 18-fold and 4-fold, respectively. In contrast, treatment of histamine-stimulated parietal cells with omeprazole or ranitidine in concentrations 100 times the IC50 value for inhibition of acid secretion in the parietal cells did not increase [3H]thymidine incorporation above the control levels, measured either by LSC or by autoradiography. Extracted DNA from stimulated parietal cells treated with [3H]omeprazole or [3H]MNNG showed no binding of [3H]omeprazole but considerable binding of [3H]MNNG. It is concluded that parietal cells can undergo DNA repair, but there is no indication that omeprazole, or its acid-derived metabolites, should cause any damage to DNA, nor does it bind to DNA in its target cell, where the highest concentrations of omeprazole and its acid-derived products are found.

The present study was aimed at assessing whether epidermal growth factor (EGF) and its receptors are present in the gastric mucosa during the healing of gastric ulcers. Immunohistochemical, immunochemical and functional studies were performed in rats after induction of ulcers in the oxyntic mucosa. Controls, which included non-operated and sham-operated animals, displayed only rare cells in the bottom of the oxyntic glands showing EGF-like immunoreactivity. Within one day after ulcer induction, a markedly increased number of chief cells in undamaged mucosa showed intense staining. Concomitantly, there was an increased immunoreactivity for EGF receptors in the mucous neck cells. Maximal immunostaining for both compounds was observed at 3 days after ulcer induction; augmented staining was still demonstrable after 3 weeks. RIA revealed significantly increased EGF concentration in the oxyntic mucosa three days after ulcer induction, and at this stage stimulated gastric acid secretion, measured in a parallel group of chronic fistula rats, indicated significant inhibition. The transient increases in EGF-like and EGF receptor immunoreactivities may stimulate gland cell proliferation. The local release of EGF-like substances may also serve to reduce gastric acidity and thereby promote ulcer healing.

A pronase digestion procedure for the isolation of gastric mucosal cells was evaluated for its usefulness in measuring unscheduled DNA synthesis (UDS). The method has been claimed to be suited for assessing the genotoxicity potential of compounds. Compounds were given orally to rats. After 13 h [3H]thymidine was injected and after another hour the animals were killed. The dissected stomachs were treated with pronase for 45 min and the incorporation of radioactivity into DNA was determined. Autoradiography was also performed both on the mucosa and on the isolated cell suspension. The cell suspensions were found to include cells undergoing normal replicative (S phase) DNA synthesis. Of all cells isolated, 4.8 +/- 0.6% consisted of S phase cells. The total amount of DNA recovered (corresponding to the number of cells isolated) was variable and ranged from 20 to 671 micrograms DNA, i.e. approximately 30-fold variation. Neither omeprazole (10, 30 and 80 mg/kg) nor ranitidine (215 mg/kg) had any effect on [3H]thymidine incorporation. The known carcinogen 1-methyl-3-nitro-1-nitrosoguanidine (MNNG) increased incorporation. Refeeding of fasted animals increased incorporation of [3H]thymidine almost 4-fold, showing that animal feeding status influences incorporation. Hydroxyurea, the selective inhibitor of S phase DNA synthesis, inhibited [3H]thymidine incorporation in control and omeprazole-treated animals as well as that induced by MNNG by 92-98%. The results clearly show that the pronase digestion procedure used releases cells undergoing normal, replicative DNA synthesis and can therefore neither be used for measurements of UDS nor for the assessment of the genotoxic potential of drugs.

For 2 weeks four groups of adult female rats were given daily peroral doses of 400 mumols/kg of one of the following inhibitors of gastric acid secretion: omeprazole, SCH 28080, SCH 32651, or ranitidine; additional control rats were given vehicle only. Six rats in each group were killed 2 h after the last dose and another six in each group at 48 h. Samples of the gastric corpus wall were processed for light and electron microscopy. The maximal reduction of stimulated acid secretion in parallel gastric fistula rats was 100%, 90%, 40%, and 85%, respectively. Forty-eight hours after the last dose only SCH 28080 produced significant inhibition of acid secretion. 'Vacuolation' of parietal cells was occasionally observed in paraffin sections. Such 'vacuoles', which were not found in plastic sections, probably represent dilated secretory canaliculi. A small number of lucid parietal cells--presumably in the process of desquamation--were seen in all groups of rats; their proportion was significantly higher 2 h after the last dose of ranitidine, SCH 28080, or SCH 32651 than in the controls. Forty-eight hours after the last dose the proportion of such degenerating parietal cells was about the same in all groups.