The OH−/H+ concept of acid-base balance: Historical development

Rahn, Hermann; Howell, B.J.

doi:10.1016/0034-5687(78)90087-7

Cited by 21 publications

(7 citation statements)

References 8 publications

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“…The water vapor pressure range used here is between 0.1 and 22 Torr. The temperature inside the chamber was measured as 22 °C, and the saturation water vapor pressure at this temperature is 22.7 Torr . The RH was calculated by dividing the corresponding water vapor pressure by the saturation vapor pressure.…”

Section: Methodsmentioning

confidence: 99%

“…The temperature inside the chamber was measured as 22 °C, and the saturation water vapor pressure at this temperature is 22.7 Torr. 30 The RH was calculated by dividing the corresponding water vapor pressure by the saturation vapor pressure. After each change of water vapor pressure in the system and prior to the STXM measurements at a particular RH, a typical delay time of approximately 5 min was necessary to ensure particles are at equilibrium with the surrounding water vapor and obtain stable and reproducible STXM images and NEXAFS spectra of individual particles.…”

Section: ' Experimental Sectionmentioning

confidence: 99%

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Spectroscopic Evidence of Keto−Enol Tautomerism in Deliquesced Malonic Acid Particles

2011

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Scanning transmission X-ray microscopy combined with near-edge X-ray absorption fine structure spectroscopy (STXM/NEXAFS) and optical microscopy coupled with Fourier transform infrared spectroscopy (micro-FTIR) have been applied to observe hygroscopic growth and chemical changes in malonic acid particles deposited on substrates. The extent of the hygroscopic growth of particles has been quantified in terms of the corresponding water-to-solute ratios (WSR) based on STXM/NEXAFS and micro-FTIR data sets. WSR values derived separately from two applied methods displayed a remarkable agreement with previous data reported in the literature. Comparison of NEXAFS and FTIR spectra acquired at different relative humidity (RH) shows efficient keto-enol tautomerization of malonic acid, with the enol form dominating at higher RH. The keto-enol equilibrium constants were calculated using relevant peak intensities in the carbon and oxygen K-edge NEXAFS spectra as a function of RH. We report strong dependence of the equilibrium constant on RH, with measured values of 0.18 ± 0.03, 1.11 ± 0.14, and 2.33 ± 0.37 corresponding to 2, 50, and 90% RH, respectively. Enols are important intermediates in aldol condensation reactions pertaining to formation and atmospheric aging of secondary organic aerosol (SOA). The present knowledge assumes that constituents of atmospheric deliquesced particles undergo aqueous chemistry with kinetic and equilibrium constants analogous to reactions in bulk solutions, which would estimate absolute dominance of the keto form of carboxylic acids. For instance, the keto-enol equilibrium constant of malonic acid in diluted aqueous solution is <10(-4). Our results suggest that in deliquesced micrometer-size particles, carboxylic acids may exist in predominantly enol forms that need to be explicitly considered in atmospheric aerosol chemistry.

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Section: Methodsmentioning

confidence: 99%

Section: ' Experimental Sectionmentioning

confidence: 99%

Spectroscopic Evidence of Keto−Enol Tautomerism in Deliquesced Malonic Acid Particles

2011

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“…It would be better to consider [H + ] increasing and [H + ] decreasing conditions and standard physiological conditions. Rahn and Howell (1978), acknowledging that they were unwittingly reincarnating a view first proposed in 1919 by Benjamin Moore, argued that the ratio of OH À /H + is a critical value for the determination of the ionized sites on proteins. In biological solutions, the ratio of OH À /H + is generally between 7 and 8 to 1 which gives an alkaline pH as defined above (Rahn and Howell 1978).…”

Section: What Is An Acid?mentioning

confidence: 99%

“…Rahn and Howell (1978), acknowledging that they were unwittingly reincarnating a view first proposed in 1919 by Benjamin Moore, argued that the ratio of OH À /H + is a critical value for the determination of the ionized sites on proteins. In biological solutions, the ratio of OH À /H + is generally between 7 and 8 to 1 which gives an alkaline pH as defined above (Rahn and Howell 1978). The ratio concept nicely explains adaptations in bodily fluids that occur with temperature changes (Howell et al 1970).…”

Section: What Is An Acid?mentioning

confidence: 99%

Intracellular pH regulation and the acid delusion

Magder

Samoukovic

2021

Can. J. Physiol. Pharmacol.

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The concentration H+ ([H+]) in intracellular fluid (ICF) must be maintained in a narrow range in all species for normal protein functions. Thus, mechanisms regulating ICF are of fundamental biological importance. Studies on the regulation of ICF [H+] have been hampered by use of pH notation,failure to consider the roles played by differences in the concentration of strong ions ( SID), the conservation of mass, the principle of electrical neutrality and that [H+] and [HCO3-] are dependent variables. This argument is based on the late Peter Stewart’s physical- chemical analysis of [H+] regulation reported in this journal nearly forty years ago. We start by outlining the principles of Stewart’s analysis and then provide a general understanding of its significance for regulation of ICF [H+]. The system may initially appear complex, but it becomes evident that changes in SID dominanate regulation of [H+]. The primary strong ions are Na+, K+ and Cl-, and a few organic strong anions. The second independent variable, PCO2, can easily be assessed. The third independent variable, the activity of intracellular weak acids ([Atot]), is much more complex but largely plays a modifying role. Attention to these principles potentially will provide new insights into ICF pH regulation.

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“…Also, the metabolites inorganic phosphate (Pi), ATP, and ADP are weak acid anions that contribute to [A tot ]. Most of the H + "produced" by metabolic and physicochemical reactions does not remain free in solution, but binds to negatively charged sites on weak acids and bases, primarily intracellular proteins (122,247 To determine the physicochemical origins of [H + ] i changes in skeletal muscle, it is necessary to measure as many independent variables as possible in biopsies of muscle taken before exercise, during exercise (optional), and at the cessation of exercise. It may also be desirable to continue with recovery from exercise, since recovery processes have received little attention and hence are less well understood.…”

Section: Muscle Intracellular Fluidmentioning

confidence: 99%

Effects of Gas Exchange on Acid‐Base Balance

Lindinger

Heigenhauser

2012

Comprehensive Physiology

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This paper describes the interactions between ventilation and acid-base balance under a variety of conditions including rest, exercise, altitude, pregnancy, and various muscle, respiratory, cardiac, and renal pathologies. We introduce the physicochemical approach to assessing acid-base status and demonstrate how this approach can be used to quantify the origins of acid-base disorders using examples from the literature. The relationships between chemoreceptor and metaboreceptor control of ventilation and acid-base balance summarized here for adults, youth, and in various pathological conditions. There is a dynamic interplay between disturbances in acid-base balance, that is, exercise, that affect ventilation as well as imposed or pathological disturbances of ventilation that affect acid-base balance. Interactions between ventilation and acid-base balance are highlighted for moderate- to high-intensity exercise, altitude, induced acidosis and alkalosis, pregnancy, obesity, and some pathological conditions. In many situations, complete acid-base data are lacking, indicating a need for further research aimed at elucidating mechanistic bases for relationships between alterations in acid-base state and the ventilatory responses.

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The OH−/H+ concept of acid-base balance: Historical development

Cited by 21 publications

References 8 publications

Spectroscopic Evidence of Keto−Enol Tautomerism in Deliquesced Malonic Acid Particles

Spectroscopic Evidence of Keto−Enol Tautomerism in Deliquesced Malonic Acid Particles

Intracellular pH regulation and the acid delusion

Effects of Gas Exchange on Acid‐Base Balance

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