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Intestinal phosphate absorption is mediated by multiple transport systems in rats.
Am J Physiol Gastrointest Liver Physiol. 2017 Apr 01; 312(4):G355-G366.AJ

Abstract

Apical inorganic phosphate (Pi) transport in the small intestine seems to be mainly mediated by the sodium/Pi cotransporter NaPi2b. To verify this role, we have studied the combined effects of pH, phosphonoformate, and Pi deprivation on intestinal Pi transport. Rats were fed, ad libitum, three fodders containing 1.2, 0.6, or 0.1% Pi for 1, 5, or 10 days. Pi deprivation (0.1%) increased both sodium-activated and sodium-independent Pi transport in brush-border membrane vesicles from the duodenum and jejunum for all three times. Alkaline pH inhibited Pi transport, despite the increasing concentration of [Formula: see text] (NaPi2b substrate), whereas acidity increased transport when the concentration of the PiT1/PiT2 substrate, [Formula: see text], was at its highest. The effect of Pi deprivation was maximal at acid pH, but both basal and upregulated transport were inhibited (70%) with phosphonoformate, an inhibitor of NaPi2b. PiT2 and NaPi2b protein abundance increased after 24 h of Pi deprivation in the duodenum, jejunum, and ileum, whereas PiT1 required 5-10 days in the duodenum and jejunum. Therefore, whereas transporter expressions are partially correlated with Pi transport adaptation, the pH effect precludes NaPi2b, and phosphonoformic acid precludes PiT1 and PiT2 as the main transporters. Transport and transporter expression were also inconsistent when feeding was limited to 4 h daily, because the 1.2% Pi diet paradoxically increased Pi transport in the duodenum and jejunum, but NaPi2b and PiT1 expressions only increased with the 0.1% diet. These findings suggest the presence of a major transporter that carries [Formula: see text] and is inhibited by phosphonoformate.NEW & NOTEWORTHY The combined effects of dietary inorganic phosphate (Pi) content, pH, and phosphonoformate inhibition suggest that the resulting apical Pi transport in the small intestine cannot be fully explained by the presence of NaPi2b, PiT1, or PiT2. We provide evidence of the presence of a new sodium-coupled Pi transporter that uses [Formula: see text] as the preferred substrate and is inhibited by phosphonoformate, and its expression correlates with Pi transport in all assayed conditions.

Authors+Show Affiliations

Department of Toxicology, University of Zaragoza, Zaragoza, Spain; and.Department of Toxicology, University of Zaragoza, Zaragoza, Spain; and. Division of Renal Diseases and Hypertension, Department of Medicine, University of Colorado Denver, Aurora, Colorado.Department of Toxicology, University of Zaragoza, Zaragoza, Spain; and.Division of Renal Diseases and Hypertension, Department of Medicine, University of Colorado Denver, Aurora, Colorado.Department of Toxicology, University of Zaragoza, Zaragoza, Spain; and sorribas@unizar.es.

Pub Type(s)

Journal Article

Language

eng

PubMed ID

28232455

Citation

Candeal, Eduardo, et al. "Intestinal Phosphate Absorption Is Mediated By Multiple Transport Systems in Rats." American Journal of Physiology. Gastrointestinal and Liver Physiology, vol. 312, no. 4, 2017, pp. G355-G366.
Candeal E, Caldas YA, Guillén N, et al. Intestinal phosphate absorption is mediated by multiple transport systems in rats. Am J Physiol Gastrointest Liver Physiol. 2017;312(4):G355-G366.
Candeal, E., Caldas, Y. A., Guillén, N., Levi, M., & Sorribas, V. (2017). Intestinal phosphate absorption is mediated by multiple transport systems in rats. American Journal of Physiology. Gastrointestinal and Liver Physiology, 312(4), G355-G366. https://doi.org/10.1152/ajpgi.00244.2016
Candeal E, et al. Intestinal Phosphate Absorption Is Mediated By Multiple Transport Systems in Rats. Am J Physiol Gastrointest Liver Physiol. 2017 Apr 1;312(4):G355-G366. PubMed PMID: 28232455.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Intestinal phosphate absorption is mediated by multiple transport systems in rats. AU - Candeal,Eduardo, AU - Caldas,Yupanqui A, AU - Guillén,Natalia, AU - Levi,Moshe, AU - Sorribas,Víctor, Y1 - 2017/02/23/ PY - 2016/07/04/received PY - 2017/01/30/revised PY - 2017/02/04/accepted PY - 2017/2/25/pubmed PY - 2017/6/27/medline PY - 2017/2/25/entrez KW - NaPi2b KW - Pi deprivation KW - Pi transport KW - PiT1 KW - PiT2 KW - pH dependence KW - small intestine SP - G355 EP - G366 JF - American journal of physiology. Gastrointestinal and liver physiology JO - Am J Physiol Gastrointest Liver Physiol VL - 312 IS - 4 N2 - Apical inorganic phosphate (Pi) transport in the small intestine seems to be mainly mediated by the sodium/Pi cotransporter NaPi2b. To verify this role, we have studied the combined effects of pH, phosphonoformate, and Pi deprivation on intestinal Pi transport. Rats were fed, ad libitum, three fodders containing 1.2, 0.6, or 0.1% Pi for 1, 5, or 10 days. Pi deprivation (0.1%) increased both sodium-activated and sodium-independent Pi transport in brush-border membrane vesicles from the duodenum and jejunum for all three times. Alkaline pH inhibited Pi transport, despite the increasing concentration of [Formula: see text] (NaPi2b substrate), whereas acidity increased transport when the concentration of the PiT1/PiT2 substrate, [Formula: see text], was at its highest. The effect of Pi deprivation was maximal at acid pH, but both basal and upregulated transport were inhibited (70%) with phosphonoformate, an inhibitor of NaPi2b. PiT2 and NaPi2b protein abundance increased after 24 h of Pi deprivation in the duodenum, jejunum, and ileum, whereas PiT1 required 5-10 days in the duodenum and jejunum. Therefore, whereas transporter expressions are partially correlated with Pi transport adaptation, the pH effect precludes NaPi2b, and phosphonoformic acid precludes PiT1 and PiT2 as the main transporters. Transport and transporter expression were also inconsistent when feeding was limited to 4 h daily, because the 1.2% Pi diet paradoxically increased Pi transport in the duodenum and jejunum, but NaPi2b and PiT1 expressions only increased with the 0.1% diet. These findings suggest the presence of a major transporter that carries [Formula: see text] and is inhibited by phosphonoformate.NEW & NOTEWORTHY The combined effects of dietary inorganic phosphate (Pi) content, pH, and phosphonoformate inhibition suggest that the resulting apical Pi transport in the small intestine cannot be fully explained by the presence of NaPi2b, PiT1, or PiT2. We provide evidence of the presence of a new sodium-coupled Pi transporter that uses [Formula: see text] as the preferred substrate and is inhibited by phosphonoformate, and its expression correlates with Pi transport in all assayed conditions. SN - 1522-1547 UR - https://www.unboundmedicine.com/medline/citation/28232455/Intestinal_phosphate_absorption_is_mediated_by_multiple_transport_systems_in_rats_ L2 - https://journals.physiology.org/doi/10.1152/ajpgi.00244.2016?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub=pubmed DB - PRIME DP - Unbound Medicine ER -