Fig. 9.

Increases in intracellular free Ca²⁺ by linopirdine and XE991 and prevention by nifedipine. NGF withdrawal did not cause a significant change in [Ca²⁺]_i measured by fura-2 imaging. In NGF-deprived medium, linopirdine (20 μm) or XE991 (10 μm) raised [Ca²⁺]_iapproximately twofold beyond the baseline. In NGF-maintained medium, [Ca²⁺]_i was increased approximately threefold above the baseline by the same concentration of linopirdine or XE991. The increase in [Ca²⁺]_i was eliminated by coapplied nifedipine (100 nm). Data were taken from at least 100 cells. *p < 0.001 indicates significant difference from the basal level of [Ca²⁺]_i; ≠p < 0.001 indicates significant difference from the corresponding group with NGF; #p < 0.001 indicates significant difference from the corresponding group without nifedipine.