Figure 7.

I–V relationship and equilibrium potential determination for the current activated by Ca²⁺ uncaging in the granular apical pole. The patch pipette contained 22 mM Cl⁻ and the calculated Cl⁻ equilibrium potential was −47 mV. (A) Voltage pulses from 0 mV to the test potential were repetitively applied, and for each Ca²⁺ uncaging event the current response was recorded both at the test potential (+30 mV to −50 mV) and at the holding potential (0 mV). As seen in both A and B, the reversal potential for the current elicited by Ca²⁺ uncaging was about −40 mV. The consistent decrease of the current amplitude measured at 0 mV from the bottom trace to the top is because of gradual decrease of the available amount of NP-EGTA within the cell. (B) I–V relationship of the current elicited by Ca²⁺ uncaging. Current amplitudes resulting from four separate uncagings were averaged and normalized, taking into account the changes in the current amplitudes measured at 0 mV.