Ca2+ channel blockers inhibit ATP-induced NFAT activation. A, Effect of nifedipine and dependence on extracellular calcium. PC12-NFAT-Luc cells were treated for 3 h with ATP and nifedipine as indicated or were stimulated with ATP in the absence of extracellular free Ca2+. Nominal Ca2+-free conditions were created using 2 mM EGTA. Statistical significance is indicated for differences vs. the control cells treated only with 300 μM ATP or 150 μM ATP ***, p < 0.001. B, Effect of BTP2. Cells were treated with varying concentrations of BTP2 during ATP stimulation. A simple inhibitor-response curve was tentatively fitted to the data, although more than one mechanism may contribute to the inhibitory effect of BTP2. The calculated IC50 is 1.5 μM (95% confidence interval 0.7-3.3 μM). Luciferase activities are expressed as the fold stimulation by the treatment relative to that in cells only treated with 300 μM ATP. Both graphs show means ± SD of 3 independent experiments.
Prasai et al. BMC Neuroscience 2011 12:90 doi:10.1186/1471-2202-12-90