Fig. 1.

Pharmacologic inhibition of conventional PKC isoforms blocks Ca²⁺-activated Cl⁻ currents in single cells. A and C: representative whole cell currents recordings. Currents were measured in standard extracellular (bath) and intracellular (pipette) solution and with an increased concentration of free Ca²⁺, up to 1 μM, in the pipette (A) or in response to addition of ATP (100 μM) to the bath solution (C). Currents measured at −80 mV (○), representing I_Cl⁻, and at 0 mV (●), representing I_K⁺, are shown. Horizontal bars below the trace indicate the presence of the conventional PKC inhibitor Gö6976 (10 μM) (A and C). A voltage-step protocol (from holding potential −40 mV, 500-ms steps from −100 to +100 mV in 20-mV increments) was obtained at basal (☆a), maximal inward current response in absence of inhibitor (☆b) and maximal inward current response in presence of inhibitor (☆c) as indicated (A and C). The I–V plots were generated from these protocols and demonstrate the current-voltage relation during basal (●) and intracellular Ca²⁺ concentration ([Ca²⁺]_i)- or ATP-stimulated conditions (maximal inward currents, due to Cl⁻ movement, in the absence ○ or presence ▽ of Gö6976). B and D: cumulative data demonstrating maximal current density (−pA/pF) in absence or presence of Gö6976, measured at −80 mV in response to [Ca²⁺]_i (B) or in response to ATP (100 μM) (D). Bars represent means ± SE; n = 5–8 for [Ca²⁺]_i, n = 6–13 for ATP. *P < 0.01 vs. basal, **P < 0.01 vs. control.