Transport model of the human Na+-coupled l-ascorbic acid (vitamin C) transporter SVCT1

2008 ◽  
Vol 294 (2) ◽  
pp. C451-C459 ◽  
Author(s):  
Bryan Mackenzie ◽  
Anthony C. Illing ◽  
Matthias A. Hediger
Keyword(s):  
Ascorbic Acid ◽  
Steady State ◽  
Vitamin C ◽  
Transport Model ◽  
Enzymatic Reactions ◽  
Acid Transport ◽  
Steady State Current ◽  
Charge Translocation ◽  
The Impact ◽  
Ascorbic Acid Transport

Vitamin C (l-ascorbic acid) is an essential micronutrient that serves as an antioxidant and as a cofactor in many enzymatic reactions. Intestinal absorption and renal reabsorption of the vitamin is mediated by the epithelial apical l-ascorbic acid cotransporter SVCT1 (SLC23A1). We explored the molecular mechanisms of SVCT1-mediated l-ascorbic acid transport using radiotracer and voltage-clamp techniques in RNA-injected Xenopus oocytes. l-Ascorbic acid transport was saturable ( K0.5 ≈ 70 μM), temperature dependent ( Q10 ≈ 5), and energized by the Na+ electrochemical potential gradient. We obtained a Na+-l-ascorbic acid coupling ratio of 2:1 from simultaneous measurement of currents and fluxes. l-Ascorbic acid and Na+ saturation kinetics as a function of cosubstrate concentrations revealed a simultaneous transport mechanism in which binding is ordered Na+, l-ascorbic acid, Na+. In the absence of l-ascorbic acid, SVCT1 mediated pre-steady-state currents that decayed with time constants 3–15 ms. Transients were described by single Boltzmann distributions. At 100 mM Na+, maximal charge translocation ( Qmax) was ≈25 nC, around a midpoint ( V0.5) at −9 mV, and with apparent valence ≈−1. Qmax was conserved upon progressive removal of Na+, whereas V0.5 shifted to more hyperpolarized potentials. Model simulation predicted that the pre-steady-state current predominantly results from an ion-well effect on binding of the first Na+ partway within the membrane electric field. We present a transport model for SVCT1 that will provide a framework for investigating the impact of specific mutations and polymorphisms in SLC23A1 and help us better understand the contribution of SVCT1 to vitamin C metabolism in health and disease.

Requirement for Na(+)-dependent ascorbic acid transport in osteoblast function

1995 ◽  
Vol 268 (6) ◽  
pp. C1430-C1439 ◽  
Author(s):  
R. T. Franceschi ◽  
J. X. Wilson ◽  
S. J. Dixon
Keyword(s):  
Ascorbic Acid ◽  
Vitamin C ◽  
Disulfonic Acid ◽  
Acid Transport ◽  
Transport Activity ◽  
Intracellular Accumulation ◽  
Extracellular Medium ◽  
Isoascorbic Acid ◽  
Transport Inhibitors ◽  
Ascorbic Acid Transport

Ascorbic acid is necessary for expression of the osteoblast phenotype. We examined whether Na(+)-dependent transport is required for MC3T3-E1 preosteoblast cells to respond to vitamin C and investigated the role of membrane transport in the intracellular accumulation and function of ascorbate. MC3T3-E1 cells were found to possess a saturable, stereoselective, Na(+)-dependent ascorbic acid transport activity that is sensitive to the transport inhibitors sulfinpyrazone, 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid, and phloretin. Transport activity showed no competition with glucose or 2-deoxyglucose and was not inhibited by cytochalasin B, indicating that it is distinct from known hexose transporters. On addition of 100 microM ascorbic acid to the extracellular medium, intracellular concentrations of 10 mM were reached within 5-10 h and remained constant for up to 24 h. A good correlation was observed between intracellular ascorbic acid concentration and rate of hydroxyproline synthesis. Although ascorbic acid was transported preferentially compared with D-isoascorbic acid, both isomers had equivalent activity in stimulating hydroxyproline formation once they entered cells. Marked stereoselectivity for extracellular L-ascorbic acid relative to D-isoascorbic acid was also seen when alkaline phosphatase and total hydroxyproline were measured after 6 days in culture. Moreover, ascorbic acid transport inhibitors that prevented intracellular accumulation of vitamin blocked the synthesis of hydroxyproline. Thus Na(+)-dependent ascorbic acid transport is required for MC3T3-E1 cells to achieve the millimolar intracellular vitamin C concentrations necessary for maximal prolyl hydroxylase activity and expression of the osteoblast phenotype.

scholarly journals Ascorbic Acid Changes Growth of Food-Borne Pathogens in the Early Stage of Biofilm Formation

2020 ◽  
Vol 8 (4) ◽  
pp. 553
Author(s):  
Jana Przekwas ◽  
Natalia Wiktorczyk ◽  
Anna Budzyńska ◽  
Ewa Wałecka-Zacharska ◽  
Eugenia Gospodarek-Komkowska
Keyword(s):  
Ascorbic Acid ◽  
Vitamin C ◽  
Food Industry ◽  
Early Stage ◽  
Food Additives ◽  
Bacterial Biofilm ◽  
Biofilm Inhibition ◽  
E Coli ◽  
Food Borne ◽  
The Impact

Since bacterial biofilm may contribute to the secondary contamination of food during the manufacturing/processing stage there is a need for new methods allowing its effective eradication. Application of food additives such as vitamin C already used in food industry as antioxidant food industry antioxidants may be a promising solution. The aim of this research was evaluation of the impact of vitamin C (ascorbic acid), in a range of concentrations 2.50 µg mL−1–25.0 mg mL−1, on biofilms of Staphylococcus aureus, Escherichia coli, and Listeria monocytogenes strains isolated from food. The efficacy of ascorbic acid was assessed based on the reduction of optical density (λ = 595 nm). The greatest elimination of the biofilm was achieved at the concentration of vitamin C of 25.0 mg mL−1. The effect of the vitamin C on biofilm, however, was strain dependent. The concentration of 25.0 mg mL−1 reduced 93.4%, 74.9%, and 40.5% of E. coli, L. monocytogenes, and S. aureus number, respectively. For E. coli and S. aureus lower concentrations were ineffective. In turn, for L. monocytogenes the biofilm inhibition was observed even at the concentration of 0.25 mg mL−1. The addition of vitamin C may be helpful in the elimination of bacterial biofilms. Nonetheless, some concentrations can induce growth of the pathogens, posing risk for the consumers’ health.

scholarly journals Endocrine Regulation of Ascorbic Acid Transport and Secretion in Luteal Cells1

1996 ◽  
Vol 54 (2) ◽  
pp. 399-406 ◽  
Author(s):  
Biljana Musicki ◽  
Pinar H. Kodaman ◽  
Raymond F. Aten ◽  
Harold R. Behrman
Keyword(s):  
Ascorbic Acid ◽  
Endocrine Regulation ◽  
Acid Transport ◽  
Ascorbic Acid Transport

Ascorbic Acid Transport by Isolated Bovine Adrenal Cortical Cells*

Endocrinology ◽  
1980 ◽  
Vol 106 (3) ◽  
pp. 811-817 ◽  
Author(s):  
FRANCES M. FINN ◽  
PHILLIP A. JOHNS
Keyword(s):  
Ascorbic Acid ◽  
Acid Transport ◽  
Cortical Cells ◽  
Adrenal Cortical Cells ◽  
Ascorbic Acid Transport

Mitochondrial ascorbic acid transport is mediated by a low-affinity form of the sodium-coupled ascorbic acid transporter-2

2014 ◽  
Vol 70 ◽  
pp. 241-254 ◽  
Author(s):  
Carola Muñoz-Montesino ◽  
Francisco J. Roa ◽  
Eduardo Peña ◽  
Mauricio González ◽  
Kirsty Sotomayor ◽  
...  
Keyword(s):  
Ascorbic Acid ◽  
Acid Transport ◽  
Acid Transporter ◽  
Ascorbic Acid Transport

scholarly journals Unintended Consequence of High-Dose Vitamin C Therapy for an Oncology Patient: Evaluation of Ascorbic Acid Interference With Three Hospital-Use Glucose Meters

2020 ◽  
pp. 193229682093218
Author(s):  
Brooke M. Katzman ◽  
Brandon R. Kelley ◽  
Gayle R. Deobald ◽  
Nikki K. Myhre ◽  
Sean A. Agger ◽  
...  
Keyword(s):  
Ascorbic Acid ◽  
Vitamin C ◽  
High Dose ◽  
Oncology Patient ◽  
Glucose Meter ◽  
High Doses ◽  
The Impact ◽  
Very High ◽  
High Dose Vitamin ◽  
Hospital Use

The use of high-dose vitamin C in cancer care has offered promising results for some patients. However, the intravenous (IV) doses used for these patients can reach concentrations that interfere with some strip-based glucose meters. We characterized the impact of vitamin C interference, from standard to the very high doses used for some cancer protocols, using three different hospital-use glucose meters. For two of the three devices tested, increasing concentrations of ascorbic acid caused false elevations in the glucose measurements. The third glucose meter did not provide inaccurate results, regardless of the vitamin C concentration present. Rather, above a certain threshold, the device generated error messages and no results could be obtained.

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