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PubMed2002

Expression and localization of AQP5 in the stomach and duodenum of the rat.

The expression, localization, and regulation of aquaporin 5 (AQP5), a member of the water channel family of proteins, was investigated in tissues of the rat gastrointestinal tract. Reverse transcriptase--polymerase chain reaction (RT--PCR) detected AQP5 mRNA in the lower stomach and duodenum. DNA sequencing confirmed that the cDNA fragment amplified had the complete sequence of the AQP5 cDNA fragment. Western blot analysis indicated the expression of a 27 kDa molecular mass AQP5 protein in the lower stomach and duodenum, which size was the same as that found for the protein in the submandibular gland and lungs. By immunohistochemistry using the IgG affinity-purified AQP5 antibody, the pyloric gland and Brunner's gland were primarily stained in the lower stomach and duodenum, respectively; a strong staining appeared in the apical and lateral membranes in both glands. These results indicate that AQP5 is present in the rat lower stomach and duodenum where it may be involved in a water transport mechanism. These results also support the idea that AQP5, and probably other aquaporins, are involved in water secretion in the stomach and duodenum although the volume of water transported via AQPs is unclear.

Animals↗
PubMed1997

Influence of age on 1,25(OH)2-vitamin D3 activation of protein kinase C in rat duodenum.

We have studied age-related changes in the non-genomic regulation of protein kinase C (PKC) by 1,25-dihydroxy-vitamin D3 [1,25(OH)2D3] and their role in 1,25(OH)2D3-dependent calcium uptake in the rat duodenum. Treatment of duodenal mucosae from 3 month-old (young) rats with hormone physiological concentrations (0.1 nM) induced an acute and transient stimulation of total tissue PKC activity which was maximal at 1 min (+80%). The responses were evidenced up to 10 nM 1,25(OH)2D3. The duodenum from 22 to 24 month old (aged) rats exhibited higher basal PKC activity which was not significantly modified after addition of the hormone. In the young duodenum PKC activation by 1,25(OH)2D3 was dependent on extracellular Ca2+ influx as it could be abolished to a great extent by EGTA and the Ca2+ channel blocker verapamil. In addition, the Ca2+ ionophore A23187 elicited a marked stimulation of duodenal mucosae PKC in young rats but was without effects in aged animals. 1,25(OH)2D3 increased the influx of 45Ca2+ in duodenal mucosae of young rats in a dose-(0.1-1 nM) and time-(1-10 min) dependent fashion. This response to the hormone was impaired in aged animals. Similarly as 1,25(OH)2D3, the PKC activator dioctanoylglycerol (DOG) rapidly (1-5 min) increased [45Ca2+] influx in duodena from young rats whereas the response to DOG was blunted in senescent animals. Furthermore, PKC inhibitors (bisindolylmaleimide, staurosporine and compound H7) abolished 1,25(OH)2D3 stimulation of Ca2+ uptake in the young duodenum. These results suggest that 1,25(OH)2D3 regulates PKC activity in the mammalian duodenum by a non-genomic mechanism which involves the rapid influx of extracellular Ca2+, and that activation of PKC, in turn, mediates hormone stimulation of intestinal Ca2+ uptake. The data also indicates that 1,25(OH)2D3 regulation of Ca2+ transport through the PKC messenger system is impaired with aging.

Age Factors↗
PubMed1999

MRI of normal and abnormal duodenum using Half-Fourier Single-Shot RARE and gadolinium-enhanced spoiled gradient echo sequences.

The objective of this research was two-fold: First, to describe the normal and abnormal MR appearances of the duodenum using combined Half-Fourier Acquisition Single Shot RARE (HASTE) and gadolinium-enhanced standard and fat suppressed spoiled gradient echo (SGE) sequences. The second objective was to assess the ability of these combined sequences to detect and characterize duodenal diseases. MR examinations were performed on fifty consecutive patients with no clinical history of duodenal diseases, who were 1) imaged with HASTE and gadolinium-enhanced standard and fat suppressed SGE sequences and 2) referred to MR examination for reasons other than duodenal diseases, and were reviewed retrospectively to determine the normal MR appearances of the duodenum. A second population of patients with abnormal duodenum who were imaged with the same MR sequences were included in the second part of this study. This population was composed of 20 consecutive patients with subsequently proven duodenal abnormalities, including: malrotation (2), diverticula (4), intussusception (1), sprue (1), polyps (2), neurofibroma (1), lymphoma (1), Zollinger Ellison syndrome (1), metastatic disease (1), Crohn's disease (1), and wall thickening and duodenitis (5). Normal measurements of the duodenum are described. Abnormalities of wall thickness and duodenal masses required combined HASTE and gadolinium-enhanced SGE images to evaluate well. Abnormalities of the bowel lumen (e.g., diverticula and intussusception), and developmental variants (e.g., malrotation), were sufficiently visualized on HASTE images alone. Bowel inflammation was best shown on gadolinium-enhanced fat suppressed SGE images. HASTE and gadolinium-enhanced fat suppressed SGE sequences are complementary techniques for the demonstration of normal and abnormal duodenum. The combined use of both sequences allows evaluation of different aspects of bowel diseases; abnormalities of position, lumen, and contents are well shown on HASTE, while inflammation is best shown on gadolinium enhanced fat suppressed SGE, and wall thickening and masses are best evaluated with the combined use of both techniques.

Adolescent↗
PubMed2001

Strangulation of the duodenum by the uterus during late pregnancy in two cows.

Two Swiss Braunvieh cows in late pregnancy underwent surgery because of a rare form of ileus due to strangulation of the duodenum at its caudal flexure by the gravid uterus. The whole uterus had passed through a gap between the mesoduodenum and duodenum and with increasing weight had led to strangulation of the duodenum. This was possible since the mesoduodenum and both walls of the greater omentum adjacent to its caudal edge were not connected with the duodenum, probably due to a congenital inhibitory malformation. A transsection and an end-to-end anastomosis of the duodenum were necessary in both cases since it was impossible to retract the gravid uterus through the defect. Postoperative recovering was uneventful in both cows, which were discharged after seven and five days respectively and calved normally about two months later.

Anastomosis, Surgical↗
PubMed1998

Murine duodenum does not go through a "solid core" stage in its embryological development.

Embryological development of duodenum is believed to go through a "solid core" stage which subsequently vacuolizes. Failure of vacuolization is thought to be the cause of duodenal atresia. This study examines the embryological development of rat duodenum. Thirty-six time-mated Sprague-Dawley rats were studied. Six fetal duodenal specimens were obtained for each gestational day from day 9 to day 20. These specimens were fixed with formalin, sectioned, stained with haematoxylin and eosin and examined under microscope. The duodenal diameters and the lumen diameters at each gestational date were measured. The foregut started to form at the gestation stage of day 10. The lumen was narrowest on days 12 and 13, but the duodenum did not become a "solid core". No vacuolization was detected through out the development of the duodenum. Embryological development of rat duodenum did not go through a "solid core" stage.

Animals↗
PubMed1985

[Protein and amino acid metabolism in the digestive tract of growing young bulls. 2. Feed protein flow into the duodenum determined with 2,6-diaminopimelic acid as a marker for crude bacterial protein].

The experimental ascertainment of the pure feed protein flowing into the duodenum on the basis of the calculation of the difference between the NH3-free crude protein flowing into the duodenum and the bacterial crude protein determined by means of DAPA showed the following results after the testing of 28 different rations at a dry matter intake adequate to the production level: With a variation of the pure protein in the crude protein content of the ration between 40 and 90%, the quota of feed protein flowing into the duodenum is 52.5%, and with a variation of the pure protein in the crude protein content between 80 and 90% it is 40.6%. The quota of feed protein flowing into the duodenum shows a negative correlation to the apparent digestibility of the organic matter (y=231.7 -2.52x +/- 14.5). With a DM-intake adequate to the production level the quota of feed protein flowing into the duodenum is neither influenced by the flow rate (kg digesta/kg DM-intake) nor by the 'dilution rate' (g bacteria-free DMD/kg live weight 0.75/h).

Amino Acids↗
PubMed1986

Adaptation of the duodenum and ileum of the rat to mid-gut resection: enzyme activity and trace metal status.

Activities of the enzymes lactase, sucrase, maltase, alkaline phosphatase, and superoxide dismutase (SOD) were measured in mucosa of duodenum and ileum of the rat after 70% resection of mid-small intestine or sham operation (transection). We also measured the concentrations of zinc, copper, and manganese in several tissues to assess trace metal homeostasis postresection. Resection resulted in decreased specific activities of disaccharidases and alkaline phosphatase in duodenum, while specific activities remained unchanged in ileum. Specific activity of total SOD (the sum of Cu-Zn and Mn SOD) and Mn SOD was the same in duodenum after resection but was markedly increased in ileum. Tissue trace metal concentrations changed minimally. Because of postresection mucosal growth, total segmental activity of disaccharidases and alkaline phosphatase was the same in duodenum and increased in ileum of resected compared to transected rats. Segmental activity of total SOD and Mn SOD doubled in duodenum and trebled in ileum of resected as compared to transected rats. Thus, total segmental enzyme activity is maintained or increased postresection by increased enterocyte proliferation rate and mucosal growth.

Alkaline Phosphatase↗
PubMed1978

Retrograde movement of digesta in the duodenum of the chick: extent, frequency, and nutritional implications.

Movement of digesta from the duodenum to the gizzard of chicks was assessed by injection of 99mTc-diethyl-triamino-pentaacetic acid via an indwelling cannula in the hepatic bile duct. The change in location of isotope with time was followed with a Gamma Camera. About 40% of the injected isotope refluxed to the gizzard within 2 minutes of injection. Clearance of the isotope from the gizzard had a T1/2 of some 20 minutes. Some possible implications of retrograde movement of digesta were examined. Cholesterol, bile salts and pancreatic enzymes were found in the gizzard at 10% to 20% of duodenal concentrations. The proteolysis and lipolysis in the gizzard and duodenum were determined in chicks fed a duet containing 91Y as a non-absorbed reference substance. Thirty percent of the feed triglycerides were found hydrolysed in the gizzard as compared to 50% to 60% in the duodenum. Proteins were 30% to 50% trichloroacetic acid soluble in the gizzard reaching almost 70% in the duodenum. A small net secretion of both fatty acids and protein was observed in the gizzard, probably due to reflux of endogenous secretions from the duodenum. The nutritional significance of these results is discussed.

Animal Nutritional Physiological Phenomena↗
PubMed1975

Villous tumors of the duodenum.

Villous tumors of the duodenum are rare, but treatment may be problematic because of their association with invasive adenocarcinoma. Two cases of villous tumor of the duodenum are described and 39 other reported cases are reviewed. Presenting symptoms were bleeding 27%; obstruction 24%; jaundice 22% and vague dyspepsia 20%. Diagnosis may be made by radiographic barium contrast evaluation of the duodenum, especially with the addition of air contrast hypotonic studies and by fibro-optic endoscopy. Twenty-seven per cent of villous tumors of the duodenum are associated with adenocarcinoma. Invasive tumor is more common in patients over 50 years old (35%), in tumors of the third and fourth portions of the duodenum (44%) and in tumors over 4 cm in diameter (30%). Local excision is the treatment of choice for benign lesions. Pancreatico-duodenectomy is recommended for tumors which include invasive carcinoma in patients without distal metastases.

Adenocarcinoma↗
PubMed1995

Impairment of nitrergic-mediated relaxation of rat isolated duodenum by experimental diabetes.

1. Diabetes mellitus is associated with changes in gastrointestinal motility. The effects of experimental diabetes, induced by streptozotocin administration to rats 3-4 weeks previously, on the nitric oxide (NO)-mediated (nitrergic) relaxation of the duodenum have now been investigated. 2. The non-adrenergic, non-cholinergic (NANC) relaxation of the isolated duodenum induced by nicotine (0.3-10 microM) or the nicotinic agonist, 1,1-dimethyl-4-phenylpiperazinium (DMPP; 10 microM) was inhibited by the NO synthase inhibitor, NG-nitro-L-arginine (3-100 microM). 3. This nitrergic relaxation induced by nicotine or DMPP of the duodenum from diabetic rats was substantially smaller than that of the tissue from control rats. 4. By contrast, the relaxation of the duodenum from diabetic rats to the NO donor, nitroprusside (0.3-10 microM) was similar to that of control tissue, whereas the relaxation to ATP (0.1-3 microM) was enhanced to a small but significant degree. 5. Incubation of duodenal tissue from control rats at 4 degrees C for 72 h, which leads to neuronal disruption, significantly attenuated the relaxation to nicotine or DMPP whereas the relaxation induced by nitroprusside or ATP was not affected. Comparable cold-storage did not affect the endothelium-dependent relaxation of rat aortic rings induced by acetylcholine (0.01-2 microM). 6. The calcium-dependent NO synthase activity in duodenal tissue, determined by the conversion of radiolabelled L-arginine to citrulline, was significantly reduced in cold-stored tissue and in tissue obtained from diabetic rats. 7. These findings in the rat duodenum indicate that a reduction in intestinal NO synthase activity is associated with an impairment of the NANC relaxation. A defect in the intestinal nitrergic innervation could thus contribute to the motility dysfunction observed in diabetes.

Adenosine Triphosphate↗
PubMed1995

Inhibitory action of PPADS on relaxant responses to adenine nucleotides or electrical field stimulation in guinea-pig taenia coli and rat duodenum.

1. The effect of pyridoxalphosphate-6-azophenyl-2',4'-disulphonic acid (PPADS) on the relaxant response to adenine nucleotides was examined in the carbachol-contracted guinea-pig taenia coli and rat duodenum, two tissues possessing P2y-purinoceptors. In addition, in the taenia coli PPADS was investigated for its effect on relaxations evoked by adenosine, noradrenaline and electrical field stimulation. In order to assess the selectivity of PPADS between P2-purinoceptor blockade and ectonucleotidase activity, its influence on ATP degradation was studied in guinea-pig taenia coli. 2. The resulting rank order of potency for the adenine nucleotides in guinea-pig taenia coli was: 2-methylthio ATP >> ATP > alpha,beta-methylene ATP with the respective pD2-values 7.96 +/- 0.08 (n = 23), 6.27 +/- 0.12 (n = 21) and 5.88 +/- 0.04 (n = 24). 3. In guinea-pig taenia coli, PPADS (10-100 microM) caused a consistent dextral shift of the concentration-response curve (CRC) of 2-methylthio ATP and ATP resulting in a biphasic Schild plot. A substantial shift was only observed at 100 microM PPADS, the respective pA2-values at this particular concentration were 5.26 +/- 0.16 (n = 5) and 5.15 +/- 0.13 (n = 6). Lower concentrations of PPADS (3-30 microM) antagonized the relaxant effects to alpha,beta-methylene ATP in a surmountable manner. An extensive shift of the CRC was produced only by 30 microM PPADS (pA2 = 5.97 +/- 0.08, n = 6), and the Schild plot was again biphasic. 4. The relaxant responses to electrical field stimulation (80 V, 0.3 ms, 5 s, 0.5-16 Hz) in guinea-pigtaenia coli were concentration-dependently inhibited by PPADS (10-100 microM).5. In guinea-pig taenia coli, the potency of ATP in inducing relaxation appeared to be independent of its rate of degradation by ecto-nucleotidases, since the Km-value (366 microM) obtained in the enzyme assay was much higher than the functional EC50-value (0.45 microM) of ATP. PPADS (3-100 microM) was only weakly active in inhibiting ecto-nucleotidase activity leaving a residual activity of 81.8 +/- 5.1% at 100 microM.Enzyme inhibition by PPADS was concentration-independent and non-competitive.6. In rat duodenum, the rank order of potency was: 2-methylthio ATP >ATP> >alpha,beta-methylene ATP,the respective pD2-values being 6.98 +/- 0.04 (n = 76), 6.26 +/- 0.02 (n = 6) and 4.83 +/- 0.02 (n = 6). Among these agonists, 2-methylthio ATP displayed the lowest apparent efficacy.7. The CRC of 2-methylthio ATP in rat duodenum was shifted to the right by PPADS (10-100 microM) ina concentration-dependent manner, and Schild analysis gave a pA2-value of 5.09 +/- 0.06 (slope = 1.02,n=14).8 PPADS was without any effect on the carbachol-induced contraction in guinea-pig taenia coli or rat duodenum and on the relaxation to noradrenaline or adenosine in guinea-pig taenia coli.9 In conclusion, the antagonistic properties of PPADS at the taenia coli and rat duodenum P2y-purinoceptors were different from those recently described at the P2x-subtype: inhibition of P2y-purinoceptor-mediated responses was observed at higher concentrations (3-100 microM vs. 1-10 (30) microM).Furthermore, we conclude that in addition to the classical P2y-subtype, which is largely PPADS-resistant,the guinea-pig taenia coli may be endowed with a distinct relaxation-mediating P2-purinoceptor subtype which is sensitive to PPADS.

Adenosine↗
PubMed1996

Characterization of P1-purinoceptors on rat isolated duodenum longitudinal muscle and muscularis mucosae.

1. P1-purinoceptors mediating relaxation of the rat duodenum longitudinal muscle and contraction of the rat duodenum muscularis mucosae were characterized by the use of adenosine and its analogues, 5'-N-ethylcarboxamidoadenosine (NECA), N6-cyclopentyl-adenosine (CPA), N6-(phenylisopropyl)adenosine (R-PIA), 2-chloroadenosine (2-CADO) and 2-p-((carboxyethyl)phenethylamino)-5'-carboxamidoadenosine (CGS21680), as well as the P1-purinoceptor antagonist 8-phenyltheophylline (8-PT) and the A1-selective antagonist, 1,3-dipropyl-8-cyclopentylxanthine (DPCPX). 2. In the rat duodenum longitudinal muscle, the order of potency of the adenosine agonists was CPA > NECA > adenosine > CGS21680. DPCPX antagonized responses to CPA and NECA at a concentration of 1 nM suggesting that they are acting at A1 receptors. A Schild plot versus CPA gave a slope near to unity (slope = 0.955) and a pA2 of 9.8 confirming that CPA was acting via A1 receptors. Schild analysis for DPCPX versus NECA, however, gave a slope of 0.674 suggesting that NECA was acting on both A1 and A2 receptors. CGS21680, a selective A2a agonist, was much less potent than adenosine suggesting that the A2 receptors are of the A2b subtype. 3. In the rat duodenum muscularis mucosae, the order of potency of the adenosine agonists was NECA > or = R-PIA = CPA > 2-CADO > adenosine, and DPCPX antagonized responses to CPA and NECA at a concentration of 1 microM. CGS21680, at a concentration of 10 microM, had no effect on this tissue. This suggests the presence of A2 receptors in this tissue and that they are of the A2b subtype. 4. These results are in agreement with previous studies in the whole duodenum showing the presence of A1 and A2b receptors causing relaxation, and this shows that the longitudinal muscle dominates the response of the whole tissue. In addition, a contractile A2b receptor has been revealed on the muscularis mucosae, the first time this subtype has been reported to elicit an excitatory response in a smooth muscle preparation.

Adenosine↗
PubMed1982

The effect of antrectomy on the number of gastrin-immunoreactive cells in the canine duodenum.

The number of gastrin-immunoreactive cells in the duodenum was assessed by immunohistochemistry in 10 dogs that had been subjected to antrectomy with gastroduodenostomy (Billroth I), in 4 dogs in which an antrectomy with gastrojejunostomy (Billroth II) had been performed and in 4 unoperated controls. Gastrin-immunoreactive cells were found only in dogs that had been subjected to antrectomy ad modum Billroth I and then only within the first 30 mm of the duodenum, i.e. in the duodenal bulb. The gastrin cells occurred scattered on the villi, in the crypts and within the glands of Brunner. In 3 of the dogs patches of antral-type mucosa occurred within the first 10 mm of the duodenum. All dogs in which gastrin-immunoreactive cells were found have in a previous study been shown to have a markedly increased tissue concentration of gastrin in the proximal third of the duodenum compared to unoperated controls. In the dogs subjected to antrectomy ad modum Billroth II in which no cells were observed the level of gastrin in duodenal tissue has been found to be moderately elevated compared to that of control dogs. The results indicate that the increased gastrin concentration in the proximal third of the duodenum following antrectomy ad modum Billroth I corresponds to an increase in the number of gastrin-immunoreactive cells in the duodenal bulb.

Animals↗
PubMed1981

Secretin release from the isolated, vascularly perfused pig duodenum.

1. A method for the isolation and vascular perfusion of the porcine pancreas and duodenum was developed. 2. The oxygen consumption of the whole preparation was similar to that of the pancreas alone, and since the duodenal arteriovenous oxygen deficit was similar to that of the total preparation, it was concluded that the duodenum respired adequately. 3. The duodenum rapidly absorbed luminally administered radioactive glucose, and this absorption was strongly inhibited by ouabain and phloridzin. 4. The duodenum secreted secretin rapidly in response to hydrochloric acid, but did not respond to any other luminal stimuli, including lipids, proteins, carbohydrates and bile. Neither was secretin release stimulated by intra-arterially injected acetylcholine. 5. By gel permeation chromatography the release immunoreactive secretin behaved identically to pure natural secretin, indicating that the tissue form and the circulating form have identical molecular size. 6. It is concluded that this model offers an unique opportunity to study the endocrine secretion of the duodenum.

Animals↗
PubMed1995

Tyrosine phosphorylation in the human duodenum.

Many growth factor receptors including the epidermal growth factor receptor function through tyrosine kinase activity. The aim of this study was to examine the constitutive level of tyrosine phosphorylation in the normal duodenum and in the hyperproliferative coeliac duodenum. A flow cytometric assay was devised using monoclonal antibody to phosphorylated (but not native) tyrosine residues to determine the levels of tyrosine phosphorylation in both CD3 positive intraepithelial lymphocytes and CD3 negative epithelial cells obtained by EDTA treatment of endoscopically obtained duodenal biopsy specimens. In addition, immunohistochemistry was performed on 18 formalin fixed coeliac duodenal biopsy specimens and eight control specimens. Tyrosine phosphorylation could be detected by flow cytometry on duodenal enterocytes and this expression was up regulated by pretreatment with epidermal growth factor. Tyrosine phosphorylation decreased with progression from the villus to the crypt, however, and was virtually undetectable on crypt enterocytes. Immunohistochemistry of the coeliac duodenum showed virtually absent tyrosine phosphorylation in the crypt. Increased tyrosine phosphorylation was detected in the infiltrating T cells. In conclusion, tyrosine phosphorylation in the duodenum is confined to the non-proliferative villous epithelium and is virtually undetectable in the proliferative crypt compartment. These findings suggest that tyrosine kinase activity is not a significant factor in the regulation of crypt cell proliferation in the human duodenum either in normal subjects or in coeliac disease patients.

CD3 Complex↗
PubMed1996

Circadian gastric acidity in Helicobacter pylori positive ulcer patients with and without gastric metaplasia in the duodenum.

BACKGROUND: The presence of gastric metaplasia allows helicobacter pylori to colonise the duodenum and this condition is thought to be acquired as a response to acid hypersecretion. This functional disorder, however, is present only in a subgroup of duodenal ulcer patients and, in addition, surface gastric metaplasia has been frequently found in the proximal duodenum of normal subjects and patients with non-ulcer dyspepsia, who cannot be certainly considered as acid hypersecretors. AIMS: To clarify the role of acid in inducing gastric type epithelium in the duodenum. This study aimed at assessing whether the pattern of circadian gastric acidity differs between H pylori positive duodenal ulcer patients with and without duodenal gastric metaplasia. PATIENTS: Seventy one patients with duodenal ulcer confirmed by endoscopy and who were found to be positive for H pylori infection by histology on antrum biopsy specimens were enrolled into this study. METHODS: Gastric type epithelium in the duodenum was found in 49 of 71 ulcer patients (69%). Continuous 24 hour gastric pH metry was performed in 50 healthy subjects and in the two subgroups of duodenal ulcer patients with and without gastric metaplasia in the duodenum. Gastric acidity was calculated for 24 hours (1700-1659), night (2000-0759) and day-time (0800-1959). RESULTS: Ulcer patients without gastric metaplasia showed a significantly higher gastric acidity (p < 0.001) than controls for every time interval considered, while the ulcer subgroup with gastric metaplasia was more acid than healthy subjects (p < 0.001) during the whole 24 hour period and the daytime. There was no difference between the two subgroups of duodenal ulcer patients with and without gastric metaplasia during the various time segments analysed. CONCLUSION: The findings confirm that the circadian gastric acidity of duodenal ulcer patients is higher than that of controls. As there is no difference in gastric pH between duodenal ulcer patients with and without gastric metaplasia, gastric hyperacidity is not specific to patients with duodenal gastric metaplasia. It is probable that this histological change is a non-specific response to mucosal injury resulting from various factors and not exclusively to acid.

Adult↗
PubMed1982

Surface epithelial HCO3(-) transport by mammalian duodenum in vivo.

Duodenal surface epithelial transport of HCO3(-) was measured by direct titration in anesthetized animals. Alkalinization of the lumen occurred in all species, although basal rates varied considerably: rats (approximately 10), cats (approximately 15), pigs (approximately 25), dogs (approximately 25), guinea pigs (approximately 40), and rabbits (approximately 170 mueq.cm-1.h-1). In cats duodenum transported HCO3(-) at a greater basal rate than jejunum (approximately 5 mueq.cm-2.h-1) and developed a higher transmucosal electrical potential difference (PD, lumen negative). Luminal application of 10 mM HCl for 5 min produced a sustained increase in the rate of duodenal HCO3(-) transport that was accompanied by a rise in appearance of E-like prostaglandin immunoreactivity in the lumen and a decrease in DNA release. In cats pretreated with indomethacin (10 mg/kg iv), acid caused only a transient increase in HCO3(-) transport. Exogenous prostaglandin E2 (1-12 microM, luminal) increased basal HCO3(-) transport in cats, rats, and dogs but had no effect on this transport in guinea pigs and rabbits. However, prostaglandin E2 increased HCO3(-) transport and PD in guinea pigs pretreated with inhibitors of tissue cyclooxygenase activity (indomethacin or aspirin) or gastric H+ secretion (cimetidine). Thus the continuous exposure of the duodenum of herbivores to HCl discharged from the stomach may itself stimulate HCO3(-) transport via an increase in endogenous prostaglandin levels and render exogenous prostaglandins ineffective. Secretin (1-15 CU/kg iv) was without effect in both cats and guinea pigs. In guinea pigs, intravenous glucagon (120-360 micrograms.kg-1.h-1) or gastric inhibitory peptide (5 micrograms/kg) both increased HCO3(-) transport but not PD. Hence, prostaglandin-stimulated and hormone-stimulated mechanisms of HCO3(-) transport probably occur in mammalian duodenum as found previously in the isolated amphibian duodenum. The results suggest that epithelial HCO3(-) transport is a major mechanism of acid disposal, and thus mucosal protection, in mammalian duodenum under the control of hormones and endogenous prostaglandins.

Animals↗
PubMed1983

Measurement of cholecystokinin octapeptide-induced motility of rat antrum, pylorus, and duodenum in vitro.

Motor effects of cholecystokinin octapeptide (CCK-OP) on rat antrum, pylorus, and duodenum have been studied in vitro under standard conditions. Intraluminal pressure changes were simultaneously measured at the three locations using a perfusion manometric system with a novel intraluminal pressure-sensor device. This device comprised an acrylic cast of the rat gastroduodenal tract containing the perfusion catheters that reached the surface of the cast with their outlets in the antrum, pylorus, and duodenum. A selective and sensitive intraluminal local pressure measurement was achieved with this pressure sensor due to its shape. CCK-OP increased base-line pressure in the antrum, pylorus, and duodenum; frequencies of phasic contractions in the antrum and pylorus; and amplitudes in the duodenum. The peptide also decreased contraction amplitudes in the antrum and pylorus and frequency of phasic contractions in the duodenum. It is concluded that the novel intraluminal pressure sensor is a useful tool for measuring local pressure changes in the gastroduodenal tract of the rat. In this experimental model, effects of CCK-OP on antral, pyloric, and duodenal base-line pressure are comparable with those observed in isolated muscle strips and in the intact organ of humans, dogs, and opossums. A different behavior, however, was observed in the force of antral and frequency of duodenal phasic contractions.

Animals↗