Figure 7.

Voltage-dependent block of TRPV6 by extracellular Mg²⁺. Intracellular solution contained 150 mM Na⁺, 10 mM EDTA and no added Mg⁺. (A) Current traces obtained in the absence of extracellular Mg²⁺. The voltage was stepped from −100 mV to potentials ranging from −140 to 120 mV before stepping back to −100 mV. (B and C) Same as A, but in the presence of the indicated concentration of free extracellular Mg²⁺ ions. Note that the voltage was stepped to 60 mV before the test steps, in order to relieve most of the Mg²⁺ block. (D) Voltage dependence of the apparent open probability (P_o) for the different extracellular Mg²⁺ concentrations. Apparent P_o was determined, analogous to Fig. 2 F, as the inward current measured immediately after the 100-ms test pulses normalized to the maximal inward current.