Fig. 5. Pharmacological study of the transient voltage-dependent K⁺ current in LNCaP-NE cells (A,B,C) and LNCaP-α_1H cells (D).

(A) On-line recording of transient voltage-dependent K⁺ currents inhibition by NiCl₂ (10 µM) and TEA-Cl (20 mM). Inset: representative membrane currents measured at −20 mV from HP −80 mV. (B) Inhibition of membrane currents (measured at −20 mV from HP −80 mV) by TEA (20 mM) and iberiotoxin (Iberio, 1 µM), but not by apamin (Apa, 500 nM). (C) Inhibition of voltage-dependent K⁺ current by si-hBK (20 nM). i–v curves shown here represent the average difference between currents obtained at HP −80 mV and those obtained at HP −40 mV. Inset: representative membrane currents measured at −20 mV from HP −80 mV. (D) Representative inhibition of membrane currents (measured at −20 mV from HP −80 mV) by si-hBK (20 nM) and si-α_1H1 and si-α_1H2 (5 nM), but not by si-Ctl (20 nM) or si-hIK1 (20 nM). Treatments for 3 days with si-hBK (20 nM) inhibit about 80% of the Ca²⁺-dependent K⁺ current in both LNCaP-NE (C) and LNCaP-α_1H (D) cells.