Arachidonic acid (AA) is a fatty acid involved in the modulation of several ion channels. Previously, we reported that AA activates the high conductance Ca²⁺- and voltage-dependent K⁺ channel (BK) in vascular smooth muscle depending on the expression of the auxiliary β1 subunit. Here, using the patch-clamp technique on BK channel co-expressed with β1 subunit in a heterologous cell expression system, we analyzed whether AA modifies the three functional modules involved in the channel gating: the voltage sensor domain (VSD), the pore domain (PD), and the intracellular calcium sensor domain (CSD). We present evidence that AA activates BK channel in a direct way, inducing VSD stabilization on its active configuration observed as a significant left shift in the Q-V curve obtained from gating currents recordings. Moreover, AA facilitates the channel opening transitions when VSD are at rest, and the CSD are unoccupied. Furthermore, the activation was independent of the intracellular Ca²⁺ concentration and reduced when the BK channel was co-expressed with the Y74A mutant of the β1 subunit. These results allow us to present new insigths in the mechanism by which AA modulates BK channels co-expressed with its auxiliary β1 subunit.

花生四烯酸 (AA) 是一种参与调节多种离子通道的脂肪酸。以前，我们报道 AA 激活高电导 Ca ²⁺ - 和电压依赖性 K ⁺血管平滑肌中的通道 (BK) 取决于辅助 β1 亚基的表达。在这里，我们在异源细胞表达系统中对与 β1 亚基共表达的 BK 通道使用膜片钳技术，分析了 AA 是否修饰了通道门控中涉及的三个功能模块：电压传感器域 (VSD)、孔域(PD) 和细胞内钙传感器结构域 (CSD)。我们提供的证据表明 AA 以直接方式激活 BK 通道，在其活动配置上诱导 VSD 稳定，观察到从门控电流记录获得的 QV 曲线显着左移。此外，当 VSD 处于静止状态且 CSD 未被占用时，AA 有助于通道开放转换。此外，激活不依赖于细胞内 Ca ²⁺当 BK 通道与 β1 亚基的 Y74A 突变体共表达时，浓度降低。这些结果使我们能够对 AA 调节与其辅助 β1 亚基共表达的 BK 通道的机制提出新的见解。