Figure 5. Conditioning applications of Ca²⁺ or Mg²⁺ inactivate the cytosolic [Ca²⁺] response to extracellularly applied Ni²⁺.

Representative traces showing the effect of extracellular [Ni²⁺] (5 mM) (open bars) on the cytosolic [Ca²⁺] (nM) of cultured TM3 cells, in various protocols wherein the cells were bathed in media with different [Ca²⁺] and [Mg²⁺] values, as indicated. Prior application of Ca²⁺ (A) or Mg²⁺ (B) resulted in a progressive concentration-dependent diminution of the cytosolic Ca²⁺ responses to Ni²⁺. The vertical scale bar refers to the bottom trace, which was obtained under conditions of 0.8 mM Mg²⁺ and 10 mM Ca²⁺.