**Figure 6.** Effects of extracellular Ca^{2+}. (A) Average current development of TRPM2 inward currents at −80 mV in response to perfusion with 1 mM ADPR in the absence of intracellular Ca^{2+} and in increasing extracellular Ca^{2+} concentrations with nDVF (closed squares, *n* = 31), 200 μM (open circles, *n* = 15), or 1 mM Ca^{2+} (closed circles, *n* = 24). Error bars represent SEM. (B) Average TRPM2 development of inward currents in response to 1 mM ADPR at 30 nM fixed intracellular Ca^{2+} and in increasing extracellular Ca^{2+} concentrations with nDVF (closed squares, *n* = 9), 200 μM (open circles, *n* = 4), or 1 mM Ca^{2+} (closed circles, *n* = 14). Error bars represent SEM. (C) Average TRPM2 development of inward currents in response to 1 mM ADPR in unbuffered intracellular Ca^{2+} conditions and with increasing extracellular Ca^{2+} concentrations with nDVF (closed squares, *n* = 14), 200 μM (open circles, *n* = 10), or 1 mM Ca^{2+} (closed circles, *n* = 7). Error bars represent SEM. (D) Average time course of TRPM2 activation induced by 1 mM ADPR and 0 Ca^{2+} in the intracellular solution (10 mM BAPTA). Control cells were kept in a NaCl-based solution supplemented with 1 mM Ca^{2+} (closed circles, dashed lines, *n* = 7). In experimental cells Ca^{2+} was removed (DVF) at the time indicated by the black bar (open circles, *n* = 5). The rate of inactivation was assessed by fitting a single exponential function (I · exp^{(−t/τ)} + Amplitude) between 36 and 100 s for control cells and between 32 and 48 s for DVF conditions. (E) Average time course of TRPM2 activation induced as in D. Control cells were kept in a NaCl-based solution supplemented with 1 mM Ca^{2+} and 1 mM Mg^{2+} (closed circles, dashed lines, *n* = 11). In experimental cells only Ca^{2+} was removed at the time indicated by the black bar (open circles, *n* = 11). The rate of inactivation was assessed at the times indicated in D. (F) Average activation of TRPM2 induced as in D. Control cells were kept in a NaCl-based solution supplemented with 1 mM Ca^{2+} and 1 mM Ba^{2+} (closed circles, dashed lines, *n* = 6). In experimental cells again only Ca^{2+} was removed at the time indicated by the black bar (open circles, *n* = 5). The rate of inactivation was assessed between 22 and 32 s for experimental cells. (G) Average activation of TRPM2 induced as in D. Cells were kept in a NaCl-based solution supplemented with either 1 mM Ca^{2+} (closed circles, *n* = 7), 1 mM Mg^{2+} (open circles, *n* = 8), or 1 mM Ba^{2+} (closed squares, *n* = 3). Note the absence of current recruitment in the absence of Ca^{2+}.