Bicarbonate or CO2?

Flear, C. T. G.

doi:10.1001/archinte.1984.04400020219047

Cited by 6 publications

(2 citation statements)

References 10 publications

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“…Spuriously elevated PCO, values multiplied by exponential pH factors in the Henderson-Hasselbalch formula will yield high bicarbonate values, and this likely explains the large 'basal' values in our experiment. Fortunately, in the range of electrolyte solutions tested, the accuracy of the pH/Pco2 method is unaffected by chemical differences between gastric juice and the buffer solutions used to define pH reference scales, by other forms of CO, in solution, and by alterations of pKa' or CY in different ionic solutions (24). The pH/Pco2 method can therefore be Measurement of GaJtric Bicarbonate 835 applied to the anacid stomach, but the data indicate that gastric bicarbonate will be underestimated (20).…”

Section: Discussionmentioning

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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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: Discussionmentioning

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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“…The presence of other ions in the system lead to the increase of K 1 and K 2 , e.g., values of equilibrium constants measured in sea water at 40 • C can reach K 1 = 2.1 × 10 −6 and K 2 = 2.3 × 10 −10 [83], comparing with calculated K 1 = 5.1 × 10 −7 and K 2 = 6.0 × 10 −11 . In biological systems they can vary significantly and are treated not as true thermodynamic constants, but rather as apparent dissociation constants determined experimentally from the measurements of pH, pCO 2 and dissolved CO 2 [84]. Several studies [85][86][87][88][89] revealed the variability of K 1 in human plasma in the range of 4.78 × 10 −7 to 1.58 × 10 −6 .…”

Section: Precipitation Of Carbonatesmentioning

confidence: 99%

Precipitation of Inorganic Salts in Mitochondrial Matrix

et al. 2020

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In the mitochondrial matrix, there are insoluble, osmotically inactive complexes that maintain a constant pH and calcium concentration. In the present paper, we examine the properties of insoluble calcium and magnesium salts, such as phosphates, carbonates and polyphosphates, which might play this role. We find that non-stoichiometric, magnesium-rich carbonated apatite, with very low crystallinity, precipitates in the matrix under physiological conditions. Precipitated salt acts as pH buffer, and, hence, can contribute in maintaining ATP production in ischemic conditions, which delays irreversible damage to heart and brain cells after stroke.

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