The Biochemical Modifications of the Brush Border Membrane Induced by Vitamin D and Parathyroid Hormone in their Actions on Phosphate Transport
Since the development of techniques for the preparation and isolation of brush border membrane vesicles (BBMV),1,2 from the luminal cell membrane of renal tubular epthelial cells considerable progress has been made in our understanding of renal tubular cell phosphate transport. A sodium dependent co-transport system capable of moving phosphate uphill against an electrochemical gradient has been characterized in BBMV. The stoichiometry of the carrier mechanism remains controversial. According to one report, it is either 2Na+:HPO 4 −2 or Na+:H2PO4−, dependent upon the charge of the phosphate species present in the bathing fluid, and phosphate transfer is electroneutral.3 However, others have reported that at pH 6 the stoichiometry is 2Na:H2PO4− and the carrier may be electrogenic at low pH.4,5 Carrier activity increases as the pH of the medium is increased in the range of 6.0–8.5.3–5 Thus, a mechanism of secondary active phosphate transport in the renal tubular brush border membrane (BBM) has been partially characterized.
KeywordsBrush Border Membrane Phosphate Transport cAMP Dependent Protein Kinase Phosphate Uptake Hypotonic Solution
Unable to display preview. Download preview PDF.
- 8.H. Murer, C. Evers, R. Stoll and R. Kinne, The effect of parathyroid hormone (PTH) and dietary phosphate on the sodium-dependent phosphate transport system located in the rat renal brush border membrane, in: “Current Problems in Clinical Biochemistry,” W. G. Guder and W. Schmidt, eds., Hans Hubor Publishers, Bern (1979).Google Scholar
- 10.T. P. Dousa and S. A. Kempson, Regulation of renal brush border membrane transport of phosphate, Mineral Electrolyte Metab. 7: 113 (1982).Google Scholar
- 15.T. A. Noland, Jr. and H. L. Henry, Parathyroid hormone, vitamin D and the regulation of protein phosphorylation in chick kidney cells, in: “Vitamin D. Chemical, Biochemical and Clinical Endocrinology of Calcium Metabolism,” A. W. Norman, K. Schaefer, D. V. Herrath and H.-G. Grigoleit, eds., Walter de Gruyter & Co., Berlin (1982).Google Scholar
- 23.C. T. Liang, J. Barnes, R. Balakir, L. Cheng and B. Sacktor, In vitro stimulation of phosphate uptake in isolated chick renal cells by 1,25-dihydroxycholecalciferol, Proc. Natl. Acad. Sci. 79:3532 (1982).Google Scholar
- 25.B. Kurnik and K. A. Hruska, Effects of 1,25(OH)2D3 on phosphate transport in a normocalcemic normophosphatemic rat model of vitamin D deficiency, (Submitted for publication).Google Scholar
- 30.S. Khalifa, S. Mills and K. A. Hruska, Stimulation of calcium uptake by parathyroid hormone in renal brush border membrane vesicles: relationship to membrane phosphorylation, J. Biol. Chem. (submitted for publication).Google Scholar
- 34.G. W. Snedecor and W. G. Cochran, Statistical Methods, The Iowa State University Press, Ames (1967).Google Scholar