Magnesium stimulates renal phosphate reabsorption

Tools

Item Type:	Article
Title:	Magnesium stimulates renal phosphate reabsorption
Creators Name:	Thumfart, J., Jung, S., Amasheh, S., Kraemer, S., Peters, H., Sommer, K., Biber, J., Murer, H., Meij, I.C., Querfeld, U., Wagner, C.A. and Mueller, D.
Abstract:	In the kidney, about 80% of the filtered phosphate (Pi) is reabsorbed along the proximal tubule. Changes in renal Pi reabsorption are associated with modulation of the sodium dependent Pi cotransporter NaPi Type IIa (NaPi-IIa) and Type IIc (NaPi-IIc) protein abundance in the brush border membrane (BBM) of proximal tubule cells. NaPi-IIa is mainly regulated by dietary Pi intake and parathyroid hormone (PTH). The purpose of the present study was to elucidate the effect of alteration in dietary magnesium (Mg(2+)) intake on renal Pi handling. Urinary Pi excretion and renal expression of NaPi-IIa and NaPi-IIc were analyzed in rats fed with normal (0.2%) or high Mg(2+) (2.5%) diet. High Mg(2+) diet resulted in decreased renal Pi excretion and increased protein expression of NaPi-IIa and NaPi-IIc. Serum FGF-23 (fibroblast growth factor 23) levels were unchanged under high Mg(2+) diet. Serum PTH levels were slightly decreased under high Mg(2+) diet. To examine whether the observed changes in renal Pi reabsorption are PTH dependent, NaPi-IIa and NaPi-IIc expression were also analyzed in parathyroidectomized (PTX) rats fed with normal or high Mg(2+) diet. In PTX rats Mg(2+) had no significant effect on renal Pi excretion or NaPi-IIa protein expression. Mg(2+) increased NaPi-IIc protein expression in PTX rats. This experiment shows for the first time on the molecular level how Mg(2+) stimulates renal Pi reabsorption. Under high Mg(2+) diet NaPi-IIa expression is dependent on PTH levels, whereas NaPi-IIc expression seems to be independent from PTH levels. Key words: magnesium, NaPi-IIa, posphate reabsorption, NaPi-IIc.
Keywords:	Parathyroid Hormone, Animal Feed, Fibroblast Growth Factors, Immunohistochemistry, Kidney, Linoleic Acids, Magnesium, Parathyroid Hormone, Parathyroidectomy, Phosphates, Messenger RNA, Type IIa Sodium-Phosphate Cotransporter Proteins, Type IIc Sodium-Phosphate Cotransporter Proteins, gamma-Linolenic Acid, Animals, Rats
Source:	American Journal of Physiology Renal Physiology
ISSN:	0363-6127
Publisher:	American Physiological Society
Volume:	295
Number:	4
Page Range:	F1126-1133
Date:	9 October 2008
Official Publication:	https://doi.org/10.1152/ajprenal.00353.2007
PubMed:	View item in PubMed

Repository Staff Only: item control page