Cobalamin, folate, methylmalonic acid, homocysteine, and gastritis markers in dementia.

The prevalence of dementia disorders, cobalamin and/or folate deficiency as well as gastritis increases with age. To investigate whether there is an association between these conditions, plasma homocysteine (Hcy), serum methylmalonic acid, serum cobalamin and blood folate concentrations were measured. Gastritis was indirectly diagnosed by measuring serum antibodies against H,K-ATPase, HELICOBACTER PYLORI and intrinsic factor, using enzyme-linked immunosorbent assays. The studied groups consisted of 47 patients with Alzheimer's disease (AD), 9 with AD pathology in combination with additive vascular lesions, 59 with vascular dementia, 8 who were cognitively impaired, and 101 control cases. Plasma Hcy concentrations were significantly elevated in the dementia groups, with the highest levels in patients with vascular pathology. We conclude that hyperhomocysteinemia is a common finding in patients with dementia disorders of different etiologies. The markers for gastritis did not contribute to an elucidation of a possible connection between this condition, dementia disorders, or cobalamin/folate deficiency.

Immunolocalization of cholecystokinin-2 receptors in rat gastric mucosa.

BACKGROUND: Gastrin exerts trophic effects on the gastric mucosa by mechanisms not yet completely elucidated. Our aim was to localize the cholecystokinin-2 (CCK2) receptor in epithelial cells of foetal and adult rat stomachs in order to determine the cell types that are directly affected by gastrin. METHODS: Gastric tissue was subjected to indirect double immunofluorescence staining with antiserum against the C-terminal decapeptide of the CCK2 receptor and antibodies against 5' bromo-2-deoxyuridine, which had been injected into the rats I h before they were killed, the acid pump H,K-ATPase, the membrane-cytoskeletal linker ezrin, pepsin/pepsinogen or histidine decarboxylase. RESULTS: Undifferentiated foetal gastric epithelial cells expressed CCK2 receptors, whereas stem cells of adult gastric glands did not exhibit immunoreactivity. However, other epithelial cells in the progenitor zone of adult gastric glands did express CCK2 receptors. Some of these cells were faintly stained for H,K-ATPase; pepsin/pepsinogen was also detected in this region. Parietal cells in the isthmus/pit region of the glands contained ezrin, and some showed weak immunoreactivity for the CCK2 receptor. As expected, enterochromaffin-like cells also expressed CCK2 receptors. CONCLUSION: Our findings are consistent with the hypothesis that a CCK2 receptor mediates direct effects of gastrin on gastric epithelial cells during both stomach organogenesis and adult life.

Characterization of oxyntic glands isolated from the rat gastric mucosa.

A simple and reproducible method for isolating oxyntic glands from the rat gastric mucosa was developed. The mucosa was incubated with pronase and EGTA, and then treated mechanically to release glands that were separated from single cells by sedimentation. Parietal cells were identified by immunostaining using a monoclonal antibody against H,K-ATPase. The glandular cells appeared morphologically intact. By careful control of the conditions of gland isolation, long glandular structures comprising hundreds of cells surrounding the lumen were obtained. Intraperitoneal injection of Br-deoxyuridine in the rat 1.5 h before the isolation procedure resulted in glands with a labeling of cells in their neck region. The glands were viable, as demonstrated by their ability to respond to various hormones. Histamine dose-dependently stimulated the acid formation which was measured as the accumulation of [14C]aminopyrine. At 100 microM histamine the accumulation was increased 5-10-fold. At 100 nM, pentagastrin potentiated the histamine stimulated accumulation by approximately 40% but pentagastrin alone did not stimulate. The oxyntic glands obtained by the present procedure appear useful for studies on cell physiology, including regulation of acid secretion, cellular interactions, and possibly also differentiation and proliferation mechanisms since long glandular fragments that contained the proliferative zone could be isolated.

The oligomeric nature of Na/K-transport ATPase.

Since the discovery of Na/K-ATPase, evidence has accumulated to suggest that 1 mol of ATP hydrolysis occurs via the Na(+)-occluded ADP-sensitive phosphoenzyme, the K(+)-sensitive phosphoenzyme and the K(+)-occluded enzyme accompanying active transport of 3Na(+) and 2K(+) according the Post-Albers scheme. However, some controversial issues have arisen concerning whether the functional unit of the enzyme is an alpha beta-protomer or a much higher oligomer, which would be related to the mechanism of transport, either sequential or simultaneous. Detailed studies of oligomer interaction and the reactivity of the enzyme and a comparison of the extent of phosphorylation with ligand-binding capacities in the presence or absence of ATP hydrolysis and others strongly suggest that the functional unit of the enzyme in the membrane is a tetraprotomer, (alpha beta)(4). They also suggest that each reaction intermediate of the Post-Albers scheme, respectively, reflects half of the site property of the intermediate and that another half binds ATP. These data may be useful not only to answer the long-standing question of whether the mechanism functions in the presence of both Na(+) and K(+) but also contribute to a better understanding of the mechanism of P-type pump ATPase in general.

Omeprazole and CYP2C19 polymorphism: effects of long-term treatment on gastrin, pepsinogen I, and chromogranin A in patients with acid related disorders.

BACKGROUND: The polymorphic enzyme CYP2C19 is of importance for the metabolism and effects of omeprazole during short-term treatment. AIM: To investigate the relationship between CYP2C19 genotype and the effects of long-term omeprazole treatment. MATERIAL AND METHODS: A total of 180 patients with acid related disorders were genotyped for wild type and mutated CYP2C19 alleles by allele-specific PCR amplification. Gastrin and chromogranin A were assessed by radioimmunoassays, and pepsinogen I and H. pylori serology were assessed by ELISA methods. RESULTS: In 108 of the patients, who received a single dose of 20 mg omeprazole, there was no difference in gastrin and chromogranin A concentrations between the three CYP2C19 genotypes. In 72 patients on long-term treatment (> 1 year) with 20 mg omeprazole daily, serum gastrin as well as plasma chromogranin A concentrations (mean +/- s.e.) were both about threefold higher in the wild type/mutated (52.1 +/- 7.6 pM and 7.3 +/- 1.3 nM (n=19), respectively) compared to wild type/wild type (14. 7 +/- 0.9 pM and 2.5 +/- 0.1 nM (n=52), respectively; both comparisons P=0.0001). In a single mutated/mutated patient on long-term treatment, both gastrin and chromogranin A were high (88 pM and 13.7 nM, respectively). Serum pepsinogen I concentration was significantly lower in wild type/mutated (n=19) patients on long-term treatment, compared with the corresponding wild type/wild type (n=49) group (147 +/- 19 microg/L vs. 193 +/- 12 microg/L, P=0. 04). CONCLUSION: Patients with one (and probably also with two) mutated CYP2C19 allele(s) on long-term treatment with omeprazole had significantly affected serum gastrin and pepsinogen I and plasma chromogranin A concentrations compared with patients with two normal alleles. This indicates that changes in gastric mucosal morphology during omeprazole treatment might be dependent upon the degree of the individual's capacity to metabolize omeprazole.

Prevalence of gastroduodenitis and Helicobacter pylori infection in a general population sample: relations to symptomatology and life-style.

Some benign and malignant diseases develop on the background of chronic gastritis or duodenitis. The present study was performed in order to determine the magnitude of these background changes with relations to symptomatology and life style in the general population. Examinations were performed in 501 volunteers (age 35-85 years). Fifty percent had gastritis; this was associated with H. pylori in 87%. H. pylori-negative gastritis was associated with regular use of NSAIDs [odds ratio 3.8 (1.6-9.9)]. Duodenitis, observed in 32%, was associated with H. pylori infection [odds ratio 2.3 (1.3-4.6)], previous cholecystectomy [odds ratio 3.6 (1.1-16.1)], and regular use of NSAIDs [odds ratio 3.0 (1.4-7.1)]. Neither gastritis nor duodenitis was associated with smoking or alcohol consumption. The rate of digestive symptoms did not differ between subjects with and without uncomplicated gastritis or duodenitis. In conclusion, half of this adult population had gastritis strongly associated with H. pylori infection. Gastritis without H. pylori infection was frequently associated with regular NSAID intake. One third had duodenitis, which was associated with H. pylori infection as well as with regular use of NSAIDs and previous cholecystectomy. Digestive symptoms were not overrepresented in uncomplicated gastritis or duodenitis.

Effects of cholecystokinin on acid formation in glands and cells isolated from rabbit and rat gastric mucosa.

Isolated gastric glands and isolated cells prepared from rabbit and rat were studied to analyse the influence of cholecystokinin octapeptide (CCK 8) on histamine stimulated parietal cell acid formation as assessed by [14C]aminopyrine sequestered in acid tissue compartments. In rabbit gastric glands, CCK 8 evoked 32+/-6% (P<0. 01) inhibition of histamine stimulated acid formation, whereas in glands prepared from rat no inhibition was recorded. Instead, CCK 8 seemed to induce a variable increase of the histamine stimulation in rat gastric glands as the aminopyrine accumulation was increased by 110+/-46% (P<0.1). Further studies on cell preparations derived from rabbit gastric mucosa revealed dual properties of CCK 8, eliciting either inhibition or stimulation of the parietal cell depending on the presence of endocrine cells. The results show that paracrine communication may be effective in glandular preparations, but seems to vary depending on species.

Helicobacter pylori-antigen-binding fragments expressed on the filamentous M13 phage prevent bacterial growth.

Colonization of the human stomach by Helicobacter pylori is associated with the development of gastritis, duodenal ulcer, mucosa-associated lymphoid tissue (MALT) lymphoma, and gastric cancer. H. pylori-antigen-binding single-chain variable fragments (ScFv) were derived from murine hybridomas producing monoclonal antibodies and expressed as a g3p-fusion protein on a filamentous M13 phage. The recombinant ScFv-phage reacted specifically with a 30-kDa monomeric protein of a H. pylori surface antigen preparation and by means of immunofluorescence microscopy the phage was shown to bind to both the spiral and coccoid forms of the bacterium. In vitro, the recombinant phage exhibited a bacteriocidal effect and inhibited specifically the growth of all the six strains of H. pylori tested. When H. pylori was pretreated with the phage 10 min before oral inoculation of mice, the colonization of the mouse stomachs by the bacterium was significantly reduced (P<0.01). The results suggest that genetic engineering may be used to generate therapy-effective phages.

Expression of extracellular matrix proteins in the fetal rat gastric mucosa.

At gestational day 16 the epithelium of the rat stomach consists of a stratified layer of undifferentiated cells, and two days later glandular structures appear. The present study was carried out to identify extracellular matrix proteins that could be involved in the epithelial cell proliferation and differentiation processes that occur in the fetal rat stomach during this period. For comparative purposes the expression of the same components in the adult gastric mucosa was examined. Pregnant Sprague-Dawley rats received an intraperitoneal injection of 5-bromo-2'-deoxyuridine to label proliferating cells. One, 3.5, or 6 h post-injection the stomachs were excised and immediately frozen. The specimens were sectioned and stained with hematoxylin and eosin or for 5-bromo-2'-deoxyuridine, cytokeratin no. 8, H,K-ATPase, and the extracellular matrix proteins fibronectin, laminin, and collagens type I and IV. A stratified layer of proliferating cells was observed in the epithelium of the fetal stomachs, while in adult stomachs proliferating cells were detected in the isthmus/neck region of the glands. Cytokeratin, an epithelial cell marker, was sparse at gestational day 16 but abundant both at gestational day 18 and in the isthmus/neck region of gastric glands of the adult stomach. The parietal cell marker H,K-ATPase could not be detected in the fetal stomachs during this period. Fibronectin was observed in the stroma of both fetal and adult stomachs. Collagen type I could only be detected in the stroma close to the oesophagus at gestational day 16. Two days later, collagen type I was abundant in the lamina propria, the submucosa and in the serosa of the fetal stomachs. In adult tissue collagen type I was detected in the surface epithelium, the submucosa and in the serosa of the stomach. Collagen type IV and laminin were expressed in the lamina propria, the basement membranes around blood vessels, muscle cells, and nerve bundles, as well as in the serosa of both 16- and 18-day-old fetal and adult rat stomachs. In conclusion, a high cell proliferation rate was observed in the epithelium at both gestational days 16 and 18. The increased expression of cytokeratin observed during this period indicates that the epithelial character of the embryonic cells becomes more distinct, while the remarkable change in the expression of collagen type I might reflect an important role of collagen type I in the development of the gastric epithelium.

Acid-labile ATP and/or ADP/P(i) binding to the tetraprotomeric form of Na/K-ATPase accompanying catalytic phosphorylation-dephosphorylation cycle.

The Na/K-ATPase has been shown to bind 1 and 0.5 mol of (32)P/mol of alpha-chain in the presence [gamma-(32)P]ATP and [alpha-(32)P]ATP, respectively, accompanied by a maximum accumulation of 0.5 mol of ADP-sensitive phosphoenzyme (NaE1P) and potassium-sensitive phosphoenzyme (E2P). The former accumulation was followed by the slow constant liberation of P(i), but the latter was accompanied with a rapid approximately 0.25 mol of acid-labile P(i) burst. The rubidium (potassium congener)-occluded enzyme (approximately 1.7 mol of rubidium/mol of alpha-chain) completely lost rubidium on the addition of sodium + magnesium. Further addition of approximately 100 microM [gamma-(32)P]ATP and [alpha-(32)P]ATP, both induced 0.5 mol of (32)P-ATP binding to the enzyme and caused accumulation of approximately 1 mol of rubidium/mol of alpha-chain, accompanied by a rapid approximately 0.5 mol of P(i) burst with no detectable phosphoenzyme under steady state conditions. Electron microscopy of rotary-shadowed soluble and membrane-bound Na/K-ATPases and an antibody-Na/K-ATPase complex, indicated the presence of tetraprotomeric structures (alphabeta)(4). These and other data suggest that Na/K-ATP hydrolysis occurs via four parallel paths, the sequential appearance of (NaE1P:E.ATP)(2), (E2P:E.ATP:E2P:E. ADP/P(i)), and (KE2:E.ADP/P(i))(2), each of which has been previously referred to as NaE1P, E2P, and KE2, respectively.

Direct evidence for in vivo reversible tyrosine phosphorylation of the N-terminal domain of the H/K-ATPase alpha-subunit in mammalian stomach cells.

In vivo reversible phosphorylation of Tyr-7 and Tyr-10 of the pig stomach H/K-ATPase alpha-chain was initially demonstrated in mammals, rat, rabbit, and pig, in the presence of vanadate + H(2)O(2). In vitro phosphorylation has also been unequivocally demonstrated via the use of protease inhibitors during membrane H/K-ATPase preparation. An amphoretic detergent permitted each intrinsic kinase to phosphorylate each fusion protein containing the requisite Tyr residues, along with a reduction in alpha-chain phosphorylation. These and other data suggest that some important enzyme systems are present in the apical membrane and that they are in sufficient proximity to participate in the reversible phosphorylation of the amino terminal soluble domain of the alpha-chain with an unknown physiological function in the membrane embedded H/K-ATPase.

Asymptomatic Helicobacter pylori gastritis is associated with increased sucrose permeability.

Our aim was to investigate whether there are changes in permeability to sucrose in asymptomatic Helicobacter pylori gastritis. Nineteen asymptomatic subjects with Helicobacter pylori-associated gastritis with no or mild mucosal atrophy and 19 age- and sex-matched normal controls were studied by peroral load of sucrose (100 g). The fraction of the given oral dose of sucrose excreted in urine was increased in subjects with Helicobacter pylori gastritis (median 0.08% versus 0.04% in controls). Sucrose excretion was not related to atrophy, intestinal metaplasia, or inflammation in the gastric mucosa. However, sucrose permeability was related to the degree of inflammatory (neutrophil) activity, since moderate activity was associated with higher sucrose excretion than mild activity (median 0.13% vs 0.07%). Asymptomatic Helicobacter pylori gastritis was associated with an increased sucrose permeability, which could be a sign of gastric mucosal leakage. This could have implications for the diseases and complications associated with Helicobacter pylori infection.

Protein kinase-dependent phosphorylation of H,K ATPase-containing membranes from rat and pig stomachs.

Previously H,K ATPase preparations from pig stomach were shown to contain intrinsic protein kinase activities which phosphorylated specific tyrosine and serine residues in the N-terminal of the alpha-chain of H,K ATPase (Togawa et al. 1996). In the present investigation, pig H,K ATPase-containing membrane preparations were compared with rat preparations. In contrast to results obtained with the alpha-subunit of H,K ATPase from pig, phosphorylation was not observed in the rat enzyme. Addition of rat preparations to the pig preparations resulted in decreased phosphorylation in pig preparations. To follow the phosphorylation of membrane proteins in vivo, 32P-loaded gastric cells prepared from rat were stimulated with several secretagogues. Proteins with molecular weights of about 120 and 80 kDa were markedly phosphorylated upon stimulation, but the alpha-subunit of H,K ATPase was not. These results suggest that phosphorylation of tyrosine or serine residues of H,K ATPase found in pig H,K ATPase preparations may not be involved in the acid secretion pathway.

Identification of Helicobacter in gastric biopsies by PCR based on 16S rDNA sequences: a matter of little significance for the prediction of H. pylori-associated gastritis?

The aim of the present study was to correlate molecular evidence of the presence of Helicobacter pylori in gastric biopsy samples, based on analysis of 16S rDNA, vacuolating toxin (vacA), urease A (ureA) and cagA genes, with the clinical, histological and serological findings in patients with H. pylori-associated gastritis. Fresh biopsy samples were collected from the gastric antrum and corpus of 22 asymptomatic volunteers with or without H. pylori-associated gastritis. Total DNA was extracted from the biopsy material and subjected to 16S rDNA PCR amplification, Southern blotting and 16S rDNA sequence analysis of the PCR products. The vacA, ureA and cagA genes were characterised by PCR amplification and Southern blot analysis. Based on partial 16S rDNA sequence analysis, DNA belonging to the genus Helicobacter was detected in gastric biopsy samples from 20 of 22 subjects, including seven of nine histologically and serologically normal controls. Six of 20 partial 16S rDNA sequences revealed variations within variable regions V3 and V4 that deviated from those of the H. pylori type strain ATCC 4350T and, therefore, possibly represented other species of Helicobacter. VacA genes identical with those of the type strain were found predominantly in the subjects with H. pylori gastritis, and all the patients except one were found to be cagA-positive. There was no evidence of false positive PCR reactions. In conclusion, the PCR-based molecular typing methods used here were apparently too sensitive when applied to the detection of H. pylori in human gastric tissues. The lack of quantitative analysis makes them inappropriate as clinical tools for the diagnosis of H. pylori-associated gastritis, despite the fact that they provide a qualitative and sensitive tool for the detection and characterisation of H. pylori in the gastrointestinal tract.

Proliferation and differentiation of cells from explants of fetal rat stomach.

The current understanding of the mechanisms controlling the proliferation and differentiation of the stem cells of the gastric oxyntic glands is limited. The aim of the present study was to develop a method for investigating proliferation and differentiation of undifferentiated cells from fetal rat stomach. Outgrowth of cells was initiated from explants of 16-day-old fetal rat stomachs. At this stage of the fetal development the gastric epithelial cells are undifferentiated. The explants were cultured in DMEM/F-12 medium supplemented with fetal calf serum only, or fetal calf serum combined with either hydrocortisone or pentagastrin. Morphological characterization by means of light microscopy, dye staining and immunostaining was used to identify the growing cells. Both hydrocortisone and pentagastrin accelerated the differentiation towards H,K-ATPase-positive cells, mucus-producing cells and other epithelial cells. H,K-ATPase-positive cells, which were identified by immunostaining with a monoclonal antibody reacting with the alpha-subunit of the H,K-ATPase, grew on top of the confluent layer of epithelioid and fibroblastoid cells. With this method in vitro investigations of the mechanisms of proliferation and differentiation of gastric mucosal cells are possible. Although by different mechanisms, both hydrocortisone and pentagastrin appear to play a regulatory role in these processes.

Detection of spiral and coccoid forms of Helicobacter pylori using a murine monoclonal antibody.

Helicobacter pylori is the major cause of gastritis. The aim of this investigation was to develop a specific antibody, which recognizes both coccoid and spiral forms of Helicobacter pylori and to test this antibody on gastric biopsy sections known to harbour coccoid bacteria. Murine monoclonal antibodies against glycine-acid extracts of five strains of Helicobacter pylori were raised. Immunofluorescence and immunoelectron microscopy showed that one antibody of the IgG1 subclass was specific for both the spiral and coccoid forms. It reacted with a 28 kDa protein that was present in all the five strains tested. Using this antibody in an indirect immunofluorescence assay of formalin-fixed antral and corpus biopsy specimens from Helicobacter pylori-associated gastritis patients showed that nine of the nine antral and five of six corpus specimens harboured the coccoid form of Helicobacter pylori. This technique thus provides a rapid and specific detection of both the spiral and coccoid forms.

Ser-27, Tyr-10 and Tyr-7 in the alpha-chain of pig stomach H+,K(+)-ATPase as Ca(2+)-dependent phosphorylatable sites by intrinsic and extrinsic protein kinases.

When pig stomach membrane H+,K(+)-ATPase preparations were incubated with [gamma-32P]ATP, Mg2+ and Ca2+, reversible phosphorylation of specific Tyr and Ser residues in the N-terminal alpha-chain of H+,K(+)-ATPase occurred without any detectable phosphorylation in other regions of the alpha-chain. Mild tosylphenylalanyl chloromethyl ketone trypsin treatment followed by reverse-phase column chromatography yielded three radioactive peptide peaks. The first peak contained both Tyr10(32P) and Tyr7(32P) and the second peak contained Tyr10(32P). The third peak contained Ser27(32P) which was also obtained after trypsin treatment of partially purified H+,K(+)-ATPase preparations phosphorylated with protein kinase-C + Ca2+ or protein kinase-A. This is the first demonstration of Ca2(+)-dependent phosphorylation of the alpha-chain of H+,K(+)-ATPase by protein kinases.

Interactions between Ca2+- and cAMP-dependent stimulatory pathways in parietal cells.

Isolated rat parietal cells were used to investigate the role of intracellular Ca2+ in the action of cAMP-dependent secretagogues and cross talk between cAMP- and Ca2+ -dependent stimulatory pathways. Aminopyrine accumulation (an index of acid produced and trapped by the parietal cells), cytosolic free Ca2+, morphological transformation and cell viability were used to investigate parietal cell function and stimulation. The increase of cytosolic free Ca2+ promoted by gastrin, or carbachol, was abolished by the intracellular Ca2+ chelator 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA, 10 microM). Also, the morphological transformations induced by dibutyryladenosine 3':5'-cyclic monophosphate (DBcAMP), gastrin, and Sp-adenosine-cyclic-3', 5'-monophosphothioate (Sp-cAMPS) were completely abolished by BAPTA (10 microM). In aminopyrine accumulation the action of 1 mM DBcAMP was dose-dependently reduced by BAPTA. The Ca2+ ionophore A23187 alone, in the range of 1 pM to 1 microM, had no effect but it dose-dependently potentiated the action of 1 mM DBcAMP in aminopyrine accumulation. The inhibitory actions of BAPTA on DBcAMP- and histamine-stimulated aminopyrine accumulation were dose-dependently reversed by A23187. Histamine-stimulated protein kinase activity and viability parameters as cellular lactate dehydrogenase (LDH) and trypan blue exclusion were not changed by BAPTA. These results indicated that in isolated parietal cells: (1) the action of cAMP-dependent secretagogues in aminopyrine accumulation and morphological transformation are dependent on cytosolic free Ca2+; (2) Ca2+ -induced morphological transformation is essential for aminopyrine accumulation; (3) a threshold level of one second messenger is required for stimulation of aminopyrine accumulation by the other second messenger.

Gastrin and carbachol require cAMP to elicit aminopyrine accumulation in isolated pig and rat parietal cells.

The role of endogenous adenosine 3',5'-cyclic monophosphate (cAMP) in the mechanisms of action of gastrin and carbachol on aminopyrine accumulation in isolated pig and rat parietal cells was investigated. In pig cells, pentagastrin (100 nM) alone stimulated aminopyrine accumulation, an action significantly reduced by the protein kinase A inhibitor Rp-adenosine 3',5'-cyclic monophosphothioate (Rp-cAMP[S]; 100 microM). In rat cells, gastrin-17 (100 nM) was incapable of stimulating aminopyrine accumulation, but it potentiated the action of histamine (100 microM). Carbachol (10 microM) stimulated aminopyrine accumulation and potentiated the action of histamine, and its action was potentiated in a dose-dependent manner by Sp-adenosine 3',5'-cyclic monophosphothioate (Sp-cAMP[S]; a cAMP analogue) in both species. The effect of carbachol was dose dependently reduced by Rp-cAMP[S]. The basal cAMP in pig parietal cells was 3.5-fold higher than that in rat parietal cells. Histamine (100 microM) and 3-isobutyl-1-methylxanthine (IBMX; 100 microM) only slightly elevated the cAMP content (1.2- to 2.9-fold the basal level) in both pig and rat parietal cells. Their combination, however, increased the cAMP level by 8- to 38-fold, but it did not increase aminopyrine accumulation above that elicited by histamine alone. Gastrin did not alter the cAMP levels in parietal cells of either of the two species. Both gastrin and carbachol increased cytosolic free Ca2+ in enriched pig and rat parietal cells.(ABSTRACT TRUNCATED AT 250 WORDS)