title: Effects of cortisol and fluoride on ion-transporting ATPase activities in cultured osteoblastlike cells.
abstract: Na+,K+-ATPase, HCO3(-)-ATPase, Ca2+,Mg2+,-ATPase, Ca2+-ATPase, and alkaline phosphatase activities were measured in cultures of osteoblastlike cells treated with fluoride and cortisol separately and in combinations. Low concentrations of cortisol increased HCO3- -ATPase (10(-11) to 10(-18) M cortisol) and alkaline phosphatase (10(-11) to 10(-9) M cortisol) activities, but higher cortisol concentrations reduced these activities. Na+,K+-ATPase, Ca2+,Mg2+-ATPase, and Ca2+-ATPase activities tended only to be reduced by cortisol. Fluoride (10(-6) and 5 X 10(-6) M) increased HCO3(-)-ATPase and alkaline phosphatase activities, but these activities were similar to controls in the presence of 10(-5) M fluoride. Ca2+,Mg2+-ATPase activity was decreased and Na+,K+-ATPase activity was increased as the concentration of fluoride increased (10(-6) to 10(-5) M). Preliminary experiments with fluoride indicated that lower concentrations (10(-7) M) were without effect. Cortisol concentrations of 10(-9) and 10(-8) M were chosen for studies with combinations of cortisol and fluoride because the effects of these concentrations on alkaline phosphatase activity were opposite, i.e. 10(-9) M increased whereas 10(-8) M decreased activity. Fluoride concentrations of 10(-6), 5 X 10(-6), and 10(-5) M were chosen because a peak of alkaline phosphatase activity occurred at 5 X 10(-6) M fluoride. Higher (10(-4) M) and lower (10(-7) M) fluoride concentrations were without effect. The effects of combinations of cortisol and fluoride depend on the enzyme activity measured. Fluoride (10(-6) M) combined with cortisol (10(-9) M) produced a peak of Na+,K+-ATPase activity. The increased activity obtained with all concentrations of fluoride alone was preserved when fluoride was combined with 10(-8) M cortisol, although the activity tended to be reduced at 5 X 10(-6) and 10(-5) M fluoride. HCO3(-)-ATPase activity was increased by fluoride combined with 10(-8) M cortisol and decreased by fluoride combined with 10(-9) M cortisol compared to the activities obtained with fluoride alone. The decrease in Ca2+,Mg2+-ATPase activity caused by fluoride alone was prevented by 10(-9) and enhanced by 10(-8) M cortisol, although all treatments produced the same activity at 10(-5) M fluoride. Ca2+-ATPase activity tended to be increased by combinations of fluoride and cortisol, but significantly so only at 10(-5) M fluoride in combinations with 10(-8) and 10(-9) M cortisol.(ABSTRACT TRUNCATED AT 400 WORDS)
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D001842:Bone and Bones / Q000166:cytology*; D002118:Calcium / Q000378:metabolism; D000252:Calcium-Transporting ATPases / Q000378:metabolism; D002478:Cells, Cultured; D005459:Fluorides / Q000494:pharmacology*; D006854:Hydrocortisone / Q000494:pharmacology*; D010006:Osteoblasts / Q000187:drug effects* / Q000201:enzymology; D011817:Rabbits; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism
chemical_list: D000469:Alkaline Phosphatase; D000251:Adenosine Triphosphatases; D000252:Calcium-Transporting ATPases; D000254:Sodium-Potassium-Exchanging ATPase; D005459:Fluorides; D002118:Calcium; D006854:Hydrocortisone