Hydration and Ion Pairing in Aqueous Sodium Oxalate Solutions

Buchner, Richard; Samani, F.; May, Peter M.; Sturm, P. von; Hefter, Glenn

doi:10.1002/cphc.200390064

Cited by 44 publications

(53 citation statements)

References 24 publications

(51 reference statements)

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“…21 In addition, oxalate forms soluble complexes with Na ϩ , Ca ϩϩ , and Mg ϩϩ that can increase its calculated size. 22 Mannitol has an estimated size of 4.2 Å 18 and has been demonstrated to traverse the size-independent "leak" pathway. 23 To test the hypothesis that oxalate traverses the claudin-based pores, we used Madin-Darby canine kidney (MDCK) II cells with inducible expression of claudin-10a.…”

Section: Effect Of Inducing Claudin-10a Expression On Tight Junction mentioning

confidence: 99%

Net Intestinal Transport of Oxalate Reflects Passive Absorption and SLC26A6-mediated Secretion

Knauf

Ko²,

Jiang³

et al. 2011

Journal of the American Society of Nephrology

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Mice lacking the oxalate transporter SLC26A6 develop hyperoxalemia, hyperoxaluria, and calciumoxalate stones as a result of a defect in intestinal oxalate secretion, but what accounts for the absorptive oxalate flux remains unknown. We measured transepithelial absorption of [14 C]oxalate simultaneously with the flux of [ 3 H]mannitol, a marker of the paracellular pathway, across intestine from wild-type and Slc26a6-null mice. We used the anion transport inhibitor DIDS to investigate other members of the SLC26 family that may mediate transcellular oxalate absorption. Absorptive flux of oxalate in duodenum was similar to mannitol, insensitive to DIDS, and nonsaturable, indicating that it is predominantly passive and paracellular. In contrast, in wild-type mice, secretory flux of oxalate in duodenum exceeded that of mannitol, was sensitive to DIDS, and saturable, indicating transcellular secretion of oxalate. In Slc26a6-null mice, secretory flux of oxalate was similar to mannitol, and no net flux of oxalate occurred. Absorptive fluxes of both oxalate and mannitol varied in parallel in different segments of small and large intestine. In epithelial cell lines, modulation of the charge selectivity of the claudin-based pore pathway did not affect oxalate permeability, but knockdown of the tight-junction protein ZO-1 enhanced permeability to oxalate and mannitol in parallel. Moreover, formation of soluble complexes with cations did not affect oxalate absorption. In conclusion, absorptive oxalate flux occurs through the paracellular "leak" pathway, and net absorption of dietary oxalate depends on the relative balance between absorption and SLC26A6-dependent transcellular secretion. 22: 224722: -225522: , 201122: . doi: 10.1681 Nephrolithiasis is the second most common chronic kidney condition after hypertension and demonstrates a rising prevalence and association with chronic kidney disease. 1 Calcium oxalate (CaOx) is the predominant component of most stones, and the level of urinary oxalate is an important risk factor for CaOx nephrolithiasis. 2,3 The amount of urinary oxalate depends on the net effect of metabolic production, intestinal absorption, and renal excretion. 4 The integral role of the intestine in oxalate homeostasis becomes most evident in diseases of intestine. Inflammatory bowel disease and small-bowel resections are conditions that are strongly associated with hyperoxaluria and CaOx nephrolithiasis. 5 New insight into the importance of the intestine in the pathogenesis of CaOx nephrolithiasis has come from studies of anion transporter SLC26A6. Slc26a6-null mice have a defect in in- J Am Soc Nephrol

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Section: Effect Of Inducing Claudin-10a Expression On Tight Junction mentioning

confidence: 99%

Net Intestinal Transport of Oxalate Reflects Passive Absorption and SLC26A6-mediated Secretion

Knauf

Ko²,

Jiang³

et al. 2011

Journal of the American Society of Nephrology

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“…These characteristics make DRS particularly apt for the study of ion-pairing processes. In favorable cases, it is also possible to determine the kinetics of ion pair formation and dissociation [17] and even structural information [18]. On the downside, DR spectra in aqueous solutions at moderate frequencies are dominated by the solvent-water response, which must be carefully subtracted to reveal the (usually much smaller) ionpair contributions.…”

Section: Measurement Of Equilibrium Constantsmentioning

confidence: 99%

When spectroscopy fails: The measurement of ion pairing

Hefter

2006

Pure and Applied Chemistry

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115

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Spectroscopic techniques such as UV/vis, NMR, and Raman are powerful tools for the investigation of chemical speciation in solution. However, it is not widely recognized that such techniques do not always provide reliable information about ion association equilibria. Specifically, spectroscopic measurements do not in general produce thermodynamically meaningful association constants for non-contact ion pairs, where the ions are separated by one or more solvent molecules. Such systems can only be properly quantified by techniques such as dielectric or ultrasonic relaxation, which can detect all ion-pair types (or equilibria), or by traditional thermodynamic methods, which detect the overall level of association. Various types of quantitative data are presented for metal ion/sulfate systems in aqueous solution that demonstrate the inadequacy of the major spectroscopic techniques for the investigation of systems that involve solvent-separated ion pairs. The implications for ion association equilibria in general are briefly discussed.

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“…For example, in recent years DRS has been used to establish the simultaneous presence of all three ion-pair types as well as triple ions in aqueous solutions of several 2:2 electrolytes Chen et al, 2005;Akilan et al, 2006a;Akilan et al, 2006b). DRS has also been used to evaluate the kinetics of ion pair formation/dissociation (Buchner et al, 2003;Tromans et al, 2004), to deduce structural information about solvent-separated IPs (Buchner and Hefter, 2002), and to determine the thermodynamic parameters for the individual steps in Scheme (II) (Akilan et al, 2006a;Akilan et al, 2006b).…”

Section: Introductionmentioning

confidence: 99%