A model to explain uphill water transport in the mammalian stomach

Rehm, Warren S.; Butler, Charlotte; Spangler, S.G.; Sanders, Sue S.

doi:10.1016/s0022-5193(70)80008-x

Cited by 24 publications

(6 citation statements)

References 29 publications

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“…Two non-absorbable markers were utilized: ''C-polyethylene glycol, with an approximate molecular weight of 3650 (I4C-PEG, 2.5 pCi/l), infused into the stomach, and phenol red (50 mg/l. 1 ml/min) perfused into the proximal duodenum (20,30). It was therefore possible to quantitate the recovery of gastric secretions and also assess for any reflux of (bicarbonate-rich) duodenal secretions into the stomach.…”

Section: In Viuo Experimentsmentioning

confidence: 99%

“…Whereas parietal secretion is hyperosmotic relative to systemic plasma (12,27,30), since H+ are formed by hydration of C02, this relationship is incompletely understood and may vary with acid concentration and with daily variations in plasma osmolality. Furthermore, the discrepancy between calculated and measured osmolality of gastric juice introduces a substantial error in the osmolality-[H+] equation.…”

Section: Acidic Stomachmentioning

confidence: 99%

See 1 more Smart Citation

Measurement of Gastric Bicarbonate Secretion in the Human Stomach: Different Methods Produce Discordant Results

Odes

Hogan

Steinbach

et al. 1992

Scandinavian Journal of Gastroenterology

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Human gastric bicarbonate secretion has been measured by back-titration, from pH and pressure of carbon dioxide (PCO2) determinations (using the Henderson-Hasselbalch formula), and from equations based on gastric juice osmolality and [H+] (osmolality-[H+] method). Since these methods show large quantitative differences in their estimations of gastric bicarbonate secretion, we examined each to define the reasons for these discrepancies and establish guidelines for future work in this area. Bicarbonate recovery from 'non-parietal' secretions (0 to 80 mM HCO3) reacting with 'pure parietal secretion' (160 mM HCl) was studied both in vitro and in the pylorus-occluded healthy human stomach during acid suppression, exogenous acidification, and pentagastrin stimulation. The pH/PCO2 method estimated HCO3- accurately under anaerobic conditions in vitro, whereas the osmolality-[H+] method (with correction factors for osmolality incorporated by us) was accurate under aerobic conditions. In the acid-suppressed stomach back-titration was significantly more accurate than the pH/PCO2 method. In the exogenously acidified and pentagastrin-stimulated stomachs the pH/PCO2 method underestimated bicarbonates, and the osmolality-[H+] method was spuriously elevated in the low range and diminished at high bicarbonate concentrations. Estimates of 'basal' bicarbonate secretion (at zero added bicarbonate) were severalfold higher by the osmolality-[H+] method (5.26 +/- 0.33 mmol/h) than by the pH/PCO2 method (1.20 +/- 0.23 mmol/h) or back-titration (0.65 +/- 0.14 mmol/h). In conclusion, gastric bicarbonate was determined most correctly by back-titration in the acid-suppressed stomach, whereas measurement of bicarbonate in the acid-secreting stomach was not accurate with any method.

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Section: In Viuo Experimentsmentioning

confidence: 99%

Section: Acidic Stomachmentioning

confidence: 99%

Measurement of Gastric Bicarbonate Secretion in the Human Stomach: Different Methods Produce Discordant Results

Odes

Hogan

Steinbach

et al. 1992

Scandinavian Journal of Gastroenterology

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“…Of particular relevance to the present case is the mechanism of transcellular water transport in mammalian gastric mucosa proposed by Rehm, Butler, Spangler and Sanders [17]. Of particular relevance to the present case is the mechanism of transcellular water transport in mammalian gastric mucosa proposed by Rehm, Butler, Spangler and Sanders [17].…”

Section: Ji = -D [Ci (D In A~/d X) + Zi(f/rt) C~ (D (~/D X)~ + CI V*mentioning

confidence: 73%

Ion-mediated water flow

et al. 1973

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Anomalous osmotic water flows may be the basis of the hypotonicity of gastric juice sampled at low rates of secretion. The anomalous osmotic flows of water produced by the exchange of hydrogen and a series of cations across the three membranes used in the electroosmotic studies (Paper I) have been obtained. The solvent flow results in part from the momentum imparted by the moving ions to the water contained in the membrane matrix. The physical parameters that regulate the rate of bi-ionic exchange and the accompanying anomalous osmotic solvent flows are: the hydration states of the membranes; the molarities of the membranes and the mobilities of the exchanging ions which are a function of ion size. Each ion in the exchange produces a flow of liquid. Assuming that the ions do not interact with one another in the membrane, the anomalous osmotic flux was assumed to be the sum of the water flows produced by each permeant ion. The anomalous osmotic flux produced by a bi-ionic exchange was calculated from electroosmotic coefficients ([EO]eatlon and lEO]c1) and the ion-exchange rates. The calculated values were all 10 to 60 % less than the observed values. Part of these differences may have resulted from concentration gradients in unstirred boundary layers adjacent to the membrane which caused an osmotic flow of water in the direction of net water movement. As in the stomach, the sodium-hydrogen exchange produced a hypotonic solution.Berkowitz and Janowitz [2] recently reported that when isoosmotic HC1 is in contact with the resting gastric mucosa, H disappears and an almost

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“…There has been speculation about the causes of hyposmolality in general (47, 64, 65, 155) and about the cause of the hyposmolality of gastric luminal contents in particular (6,37,120,139,146). 'Hyposmolality' in the context of 'exchange-diffusion' has been explained by assuming that during 'exchange' of hydrogen for sodium ions across the gastric mucosa, some degree of hyposmo lality of the luminal contents may result from the greater rate of diffusion of hydrogen ions out of the lumen than sodium ions into the lumen (120,146).…”

Section: Mechanisms O F Hyposmolalitymentioning

confidence: 99%

“…'Hyposmolality' in the context of 'exchange-diffusion' has been explained by assuming that during 'exchange' of hydrogen for sodium ions across the gastric mucosa, some degree of hyposmo lality of the luminal contents may result from the greater rate of diffusion of hydrogen ions out of the lumen than sodium ions into the lumen (120,146). It has also been suggested that the structural organisation of the gastric mucosa, particularly of the gastric pits, contributes to the hyposmolality resulting from different mobilities of the two cations (120).…”

Section: Mechanisms O F Hyposmolalitymentioning

confidence: 99%

Back-Diffusion – Fact or Fiction?

Þjóðleifsson

Wormsley

1977

Digestion

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Alterations in the concentration of acid in gastric juice secreted at different flow rates and disappearance of acid from the gastric lumen, when the gastric mucosa is exposed to acid luminal contents, have been interpreted as indicating ‘back-diffusion’ of acid into the gastric mucosa from the luminal contents. The loss of acid from the gastric contents increases when the mucosa is exposed to certain drugs or is diseased, giving rise to the suggestion that the increased degree of ‘back-diffusion’ of acid indicates mucosal damage, reflecting a breakdown of the gastric mucosal ‘barrier’ to back-diffusion of acid from the gastric lumen. The change in the ‘barrier’ properties of the gastric mucosa has been found to be associated with change in the electrical properties of the mucosa, so that alterations of the transmucosal potential difference has been considered to denote gastric mucosal damage. The case for every one of these hypotheses and for their underlying assumptions is discussed and found wanting for lack of direct evidence.

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A model to explain uphill water transport in the mammalian stomach

Cited by 24 publications

References 29 publications

Measurement of Gastric Bicarbonate Secretion in the Human Stomach: Different Methods Produce Discordant Results

Measurement of Gastric Bicarbonate Secretion in the Human Stomach: Different Methods Produce Discordant Results

Ion-mediated water flow

Back-Diffusion – Fact or Fiction?

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