Fig. 5.

Effect of the inhibitor levamisole on bone formation. This study used CLCN3^−/− mouse mesenchymal stem cells, which mineralize well in vitro and express increased ClC5 (17) (Fig. 6). A: effect of 50 µg/ml levamisole on alkaline phosphatase activity and formation of mineralized bone. Cultures were maintained in bone-supporting medium for 2 wk, with or without levamisole (50 µg/ml) added. Both mineralization (von Kossa) and alkaline phosphatase activity were suppressed by levamisole. B–E: parallel effects of levamisole-inhibiting expression of mRNAs for alkaline phosphatase, Cl⁻/H⁺ antiport-5 (ClC5), Na⁺/H⁺ exchanger 1 (NHE1), and Na⁺/H⁺ exchanger regulatory factor 1 (NHERF1). In each case, results are relative to glyceraldehyde-3-phosphatase dehydrogenase mRNA and are shown as n = 3; mean ± SD. **P < 0.01, signficant differences.