Osteoclastic bone resorption is followed by osteoblastic bone formation io the bone remodeling sites. The coupling of bone formation Is mediated by several growth factors in the bone matrix, such as TGF-β and IGF-I. The local concentration of calcium ion at the resorption sites is reported to rise t...
Osteoclastic bone resorption is followed by osteoblastic bone formation io the bone remodeling sites. The coupling of bone formation Is mediated by several growth factors in the bone matrix, such as TGF-β and IGF-I. The local concentration of calcium ion at the resorption sites is reported to rise to as high as 40 mM. It is therefore, expected that the Ca?? concentration in the microenvironment of the resorption sites would increase to some degree and both osteoblasts and osteoclasts have extracellular Ca sensing mechanism. From these findings, the possibilities that high (Ca??)?? might play a role in the bone remodeling regulation, has been postulated. To examine the role of high (Ca??), in the bone metabolism. effect of high (Ca??)?? on the proliferation and activity of osteoblastic cells were examined, HOS cells were used for osteoblastic model, DMEM contains 1.8 mM Ca and we changed the Ca concentration of culture medium by adding appropriate amount of CaClx (3, 5, 7 and 10 mM), Effect of various concentration of extracellular Ca on the cell number, alkaline phosphatase activity, NBT reduction, nitric oxide production and gelatinese activity was studied, High (Ca??)?? decreased the cell proliferation as determined by cell counting after 48hr treatment. This effect was greatest at the medium Ca concentration of 7 mM. AJkaIine phosphatase activity was inhibited by high (Ca??)?? dose-dependently and showed significant inhibition by 3, 5, 7 and 10 mM Ca concentrations, To determine the effect of high (Ca??)?? on the superoxide production by osteoblasts, NBT reduction assay was undertaken after treatment of HOS cells with various concentrations of Ca. High (Ca??)?? decreased NBT reduction dose-dependently showing that high (Co??)?? may decrease the superoxide production by osteoblasts. Nitrite concentration in the media of HOS cells was negligible after 48hr culture period, and high (Ca??)?? had no effect on the nitric oxide production by this cell. Finally, HOS cells can produce and secrete the gelatinase (gelatinase A type as determined by molecular weight of about 65,000) into culture media. High (Ca??)?? decreased the gelatinase activity of concentrated conditioned media of HOS cell cultures. These findings suggest that high (Ca??)?? may inhibit the proliferation and differentiation of osteoblasts, therefore, it may play a important role in bone metabolism.
Osteoclastic bone resorption is followed by osteoblastic bone formation io the bone remodeling sites. The coupling of bone formation Is mediated by several growth factors in the bone matrix, such as TGF-β and IGF-I. The local concentration of calcium ion at the resorption sites is reported to rise to as high as 40 mM. It is therefore, expected that the Ca?? concentration in the microenvironment of the resorption sites would increase to some degree and both osteoblasts and osteoclasts have extracellular Ca sensing mechanism. From these findings, the possibilities that high (Ca??)?? might play a role in the bone remodeling regulation, has been postulated. To examine the role of high (Ca??), in the bone metabolism. effect of high (Ca??)?? on the proliferation and activity of osteoblastic cells were examined, HOS cells were used for osteoblastic model, DMEM contains 1.8 mM Ca and we changed the Ca concentration of culture medium by adding appropriate amount of CaClx (3, 5, 7 and 10 mM), Effect of various concentration of extracellular Ca on the cell number, alkaline phosphatase activity, NBT reduction, nitric oxide production and gelatinese activity was studied, High (Ca??)?? decreased the cell proliferation as determined by cell counting after 48hr treatment. This effect was greatest at the medium Ca concentration of 7 mM. AJkaIine phosphatase activity was inhibited by high (Ca??)?? dose-dependently and showed significant inhibition by 3, 5, 7 and 10 mM Ca concentrations, To determine the effect of high (Ca??)?? on the superoxide production by osteoblasts, NBT reduction assay was undertaken after treatment of HOS cells with various concentrations of Ca. High (Ca??)?? decreased NBT reduction dose-dependently showing that high (Co??)?? may decrease the superoxide production by osteoblasts. Nitrite concentration in the media of HOS cells was negligible after 48hr culture period, and high (Ca??)?? had no effect on the nitric oxide production by this cell. Finally, HOS cells can produce and secrete the gelatinase (gelatinase A type as determined by molecular weight of about 65,000) into culture media. High (Ca??)?? decreased the gelatinase activity of concentrated conditioned media of HOS cell cultures. These findings suggest that high (Ca??)?? may inhibit the proliferation and differentiation of osteoblasts, therefore, it may play a important role in bone metabolism.
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