[Zinc modulates the Ca(2+)-ATPase activity of rat osteoblast membrane]

The effect and mechanism of zinc on Ca(2+)-ATPase and Na+, K(+)-ATPase activity of rat osteoblast membrane were studied. The activities were measured by colorimetric method. The effect of special inhibitors of protein kinase C or calmodulin on membrane Ca(2+)-ATPase and Na+, K(+)-ATPase activity which induced by zinc were also examined. The results showed that zinc could increase membrane Ca(2+)-ATPase activity, but no influence was observed on Na+, K(+)-ATPase activity. R24571, a special inhibitor of calmodulin, had no effect on membrane Ca(2+)-ATPase activity. Calmodulin also could not promote the basic Ca(2+)-ATPase activity of membrane. But trifluoperazine, a special inhibitor of protein kinase C, obviously reduced its activity. It was concluded that the modulation of zinc on membrane Ca(2+)-ATPase activity of rat osteoblast could be mediated by protein kinase C.