Figure 3. Ca²⁺ channel blocker, but not the SA or Na⁺ or K⁺ channel blocker, inhibits the mechanical induction of PTHrP mRNA. Day 12 (matrix-forming) chondrocytes were subjected to a cyclic mechanical strain of 12% elongation in the presence of different channel blockers for 12 hrs, and the expression of PTHrP mRNA was examined by real-time RT-PCR. Values were normalized with the expression level of GAPDH and denoted as the fold-increase of PTHrP mRNA expression relative to control samples (0% elongation; without channel blockers). Mean ± SD, n = 3, **p < 0.01, *p < 0.05.