Figure 3.

ZnR is distinct from the CaR. (a) HT29 cells were superfused with 2 mM Ca²⁺-containing Ringer's solution to activate the CaR. At the time indicated by the arrow, Zn²⁺ (100 μM) was added to the superfusing solution. The response to Zn²⁺ was ≈7-fold larger than the response to Ca²⁺. (b) HEK293 cells transfected with the CaR or the vector alone (Control) were superfused with Ringer's solution containing 0.3 mM Ca²⁺ and 250 μM Zn²⁺; then, 2 mM Ca²⁺ was added to activate the CaR. Cells expressing the CaR did not respond to the application of Zn²⁺.