Basolaterally localized increases in [Ca²⁺] fail to activate K and Cl channels. (A) A bright field and pseudocolor image series is shown for a cell in which [Ca²⁺] was increased under the basal PM (blue dot) using laser parameters identical to Fig 3. (B) The kinetic demonstrates that a substantial and localized increase in fluorescence was evoked. Increasing the [Ca²⁺] at the basal PM failed to significantly activate K channels (C, top) or Cl channels in TEA-Cl solution (C, bottom). (D) Paired experiments before and after flash. (E) Similar experiments were performed, but the laser power output was increased to generate a larger increase in [Ca²⁺], as shown in E (images) and F (kinetic). (G) Under these conditions, no increase in K⁺ conductance could be evoked. (H) Paired experiments demonstrating that no significant increase in either K⁺ (left) or Cl⁻ (right) conductance occurred under these conditions.