Calciotropic hormones raise the chemically detectable [Pi] in UMR 106-06 osteoblast-like cells.
Uptake of orthophosphate (Pi) by osteoblast-like cells is known to be stimulated by parathyroid hormone (PTH), but effects on intracellular [Pi] have not been investigated. Here we show in rat osteoblast-like cells (UMR 106-06) that PTH (10(-11) to 10(-7) M) increases both 32Pi uptake and cellular [Pi] by up to 50 per cent. 1,25 Dihydroxyvitamin D3 (1,25D) (10(-12) to 10(-6) M) and salmon calcitonin (CT) (10(-12) to 10(-6) g ml-1) also increased cellular [Pi] (by up to 60 per cent), but the percentage increases in total cellular 32Pi uptake were smaller. The effects of 1,25D were transient (observable at 80 min and 6 h but not 24 h), and were also observed with 24,25 dihydroxy- and 25 hydroxyvitamin D3. Transient degradation of organic phosphorus pools to Pi might contribute to this increased [Pi]. These pools remain to be identified but were not shown to be phospholipids. Foetal bovine serum also affected cellular [Pi]. Care is therefore needed in distinguishing direct hormonal effects on cellular [Pi] from indirect effects arising from changes in the rate of cell growth.
Ahmado
A
A
Department of Human Metabolism and Clinical Biochemistry, Medical School, Sheffield, U.K.
Khouja
H I
HI
Kemp
G J
GJ
Guilland-Cumming
D F
DF
Russell
R G
RG
Bevington
A
A
D015650:24,25-Dihydroxyvitamin D 3 / Q000494:pharmacology; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D001790:Blood Physiological Phenomena; D002112:Calcifediol / Q000494:pharmacology; D002116:Calcitonin / Q000494:pharmacology; D002117:Calcitriol / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002417:Cattle; D008563:Membrane Lipids / Q000378:metabolism; D010006:Osteoblasts / Q000187:drug effects* / Q000378:metabolism; D010281:Parathyroid Hormone / Q000494:pharmacology*; D010710:Phosphates / Q000378:metabolism*; D010743:Phospholipids / Q000378:metabolism; D051381:Rats; D015290:Second Messenger Systems / Q000187:drug effects; D014407:Tumor Cells, Cultured
D008563:Membrane Lipids; D010281:Parathyroid Hormone; D010710:Phosphates; D010743:Phospholipids; D015650:24,25-Dihydroxyvitamin D 3; C028815:salmon calcitonin; D002116:Calcitonin; D002117:Calcitriol; D002112:Calcifediol; D002118:Calcium