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Regulation of the phosphate (Pi) concentration in UMR 106 osteoblast‐like cells: Effect of Pi, Na + and K +
Author(s) -
Kemp Graham J.,
Khouja Hamed I.,
Ahmado Abdulla,
Russell R. Graham G.,
Bevington Alan
Publication year - 1993
Publication title -
cell biochemistry and function
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.933
H-Index - 61
eISSN - 1099-0844
pISSN - 0263-6484
DOI - 10.1002/cbf.290110103
Subject(s) - pi , extracellular , osteoblast , phosphate , chemistry , ouabain , phosphorus , biochemistry , sodium , in vitro , organic chemistry
Osteoblast‐like cells possess Na‐dependent transporters which accumulate orthophosphate (Pi) from the extracellular medium. This may be important in bone formation. Here we describe parallel measurements of Pi uptake and cellular [Pi] in such cells from the rat (UMR 106–01 and UMR 106–06) and human (OB), and in non‐osteoblastic human fibroblasts (Detroit 532 (DET)). In UMR 106–01, cellular [Pi] was weakly dependent on extracellular [Pi] and higher than expected from passive transport alone. [ 32 Pi]‐uptake was inhibited by Na deprivation, but paradoxically increased on K deprivation. With Na, 87 per cent of cellular 32 P was found in organic phosphorus pools after only 5 min. Na deprivation also decreased cellular [Pi], in both UMR 106–01 and DET, but the decrease was smaller than that in [ 32 Pi]‐uptake. Ouabain decreased [ 32 Pi]‐uptake and cellular [Pi] in DET, but not in UMR 106–01. Regulation of cellular [Pi] is therefore at least partly dependent on Na/Pi co‐transport, but this does not seem to be an exclusive property of osteoblasts.