Figure 2.

Effects of the BKCa channel blockers IbTX and TEA on K⁺-current recorded in SH-SY5Y neuronal cell line. The effects of IbTX and TEA were investigated on the K⁺-current recorded in asymmetrical K⁺ ions concentrations (int K⁺: 132 × 10⁻³ M; ext K⁺: 2.8 × 10⁻³ M), in the presence of internal 1.6 × 10⁻⁶ M concentration of free Ca²⁺ ions, in the range of potentials going from −150 to +110 mV, HP = −60 mV using whole cell patch clamp technique. The whole cell K⁺-current was a leak subtracted and normalized to capacitance. (A) I/V relationship in the absence or presence of IbTX from a single patch. IbTX (4 × 10⁻⁷ M) reduced the outward K⁺-current of the −53% at +30 mV (Vm) in this patch. (B) IbTX (10⁻¹⁰–10⁻⁵ M) induced a concentration-dependent reduction of the K⁺-current at +30 mV (Vm). (C) I/V relationship in the absence or presence of increasing concentrations of unselective K⁺ channel blocker TEA from a single patch. (D) TEA (10⁻⁵–10⁻³ M) induced a concentration-dependent reduction of the outward K⁺- current. A full reduction of the K⁺-current on −100% at +30 mV (Vm) was observed in the presence of TEA at 10⁻³ M concentration.