Matrix extracellular phosphoglycoprotein causes phosphaturia in rats by inhibiting tubular phosphate reabsorption.
BACKGROUND
Matrix extracellular phosphoglycoprotein (MEPE), first isolated from tumour-derived tissue from a patient with oncogenic hypophosphataemia, is a putative phosphatonin that has received much less attention than fibroblast growth factor-23. To date, its effect on renal tubular phosphate reabsorption remains undefined.


METHODS
A renal clearance study was performed in anaesthetized rats infused intravenously with a range of doses of MEPE.


RESULTS
MEPE had no effect on glomerular filtration rate (inulin clearance) but caused rapid, dose-dependent increases in absolute and fractional phosphate excretion, wholly attributable to reduced phosphate reabsorption. At a maximal dose, MEPE increased fractional phosphate excretion more than 2-fold, whereas no change was observed in time controls.


CONCLUSIONS
The results lend support to the hypothesis that MEPE contributes to the phosphaturia of oncogenic hypophosphataemia and of hypophosphataemic rickets.
Dobbie
Hamish
H
Department of Physiology and Centre for Nephrology, University College London, Hampstead Campus, Rowland Hill Street, London NW3 2PF, UK.
Unwin
Robert J
RJ
Faria
Nuno J R
NJ
Shirley
David G
DG
D000042:Absorption; D000818:Animals; D016326:Extracellular Matrix Proteins / Q000502:physiology*; D006023:Glycoproteins / Q000502:physiology*; D007015:Hypophosphatemia, Familial / Q000209:etiology*; D007684:Kidney Tubules / Q000378:metabolism*; D008297:Male; D010710:Phosphates / Q000378:metabolism*; D010750:Phosphoproteins / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley
D016326:Extracellular Matrix Proteins; D006023:Glycoproteins; C417185:Mepe protein, rat; D010710:Phosphates; D010750:Phosphoproteins