Carbon monoxide activates KCa channels in newborn arteriole smooth muscle cells by increasing apparent Ca2+ sensitivity of alpha-subunits.
Carbon monoxide activates KCa channels in newborn arteriole smooth muscle cells by increasing apparent Ca2+ sensitivity of alpha-subunits.
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DOI：
10.1152/ajpheart.00782.2003
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发表时间：
2004-02
期刊：
影响因子：
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通讯作者：
Qi Xi;Dilyara Tcheranova;H. Parfenova;B. Horowitz;C. Leffler;J. Jaggar
中科院分区：
文献类型：
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作者：
Qi Xi;Dilyara Tcheranova;H. Parfenova;B. Horowitz;C. Leffler;J. Jaggar
一氧化碳 (CO) 是一种气体血管舒张剂，由许多细胞类型产生，包括内皮细胞和平滑肌细胞。本研究的目的是探讨新生猪脑小动脉平滑肌细胞中大电导 Ca(2+) 激活的 K(+) (K(Ca)) 通道 CO 激活的信号传导机制。在 0 mV 的完整细胞中，CO (3 µM) 或从新型光激活 CO 供体十羰基二锰 (10 µM) 释放的 CO，K(Ca) 通道活性分别增加 4.9 倍或 3.5 倍。 CO 激活的 K(Ca) 通道不会被可溶性鸟苷酸环化酶抑制剂 1-H-[1,2,4]恶二唑并[4,3-a]喹喔啉-1-酮 (25 microM) 阻断。在 0 mV 的由内向外斑片中，CO 使 K(Ca) 通道的 Ca(2+) 浓度-响应曲线向左移动，并将 Ca(2+) 的表观解离常数从 31 µM 降低至 24 µM。 Western blotting数据表明新生儿K(Ca)通道的Ca(2+)敏感性较低可能是由于β亚基与α亚基比率降低所致。 K(Ca)通道的CO激活是Ca(2+)依赖性的。当胞质膜表面有 10 µM 游离 Ca(2+) 时，CO 使开放概率增加 3.7 倍，但在 300 nM Ca(2+) 下，开放概率仅增加 1.1 倍。 CO 使 HEK-293 细胞中表达的 cslo-alpha 电流的电流-电压关系左移，在 +50 mV 时使电流增加 2.2 倍。总之，数据表明，在新生小动脉平滑肌细胞中，CO 通过直接作用于 α 亚基来激活低亲和力 K(Ca) 通道，从而增加表观 Ca(2+) 敏感性。 CO 对 K(Ca) 通道的微摩尔 Ca(2+) 敏感性的最佳调节将导致信号传导方式的优先激活，例如 Ca(2+) 火花，从而提高该范围内的肌膜下 Ca(2+) 浓度。
Carbon monoxide (CO) is a gaseous vasodilator produced by many cell types, including endothelial and smooth muscle cells. The goal of the present study was to investigate signaling mechanisms responsible for CO activation of large-conductance Ca(2+)-activated K(+) (K(Ca)) channels in newborn porcine cerebral arteriole smooth muscle cells. In intact cells at 0 mV, CO (3 microM) or CO released from dimanganese decacarbonyl (10 microM), a novel light-activated CO donor, increased K(Ca) channel activity 4.9- or 3.5-fold, respectively. K(Ca) channel activation by CO was not blocked by 1-H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (25 microM), a soluble guanylyl cyclase inhibitor. In inside-out patches at 0 mV, CO shifted the Ca(2+) concentration-response curve for K(Ca) channels leftward and decreased the apparent dissociation constant for Ca(2+) from 31 to 24 microM. Western blotting data suggested that the low Ca(2+) sensitivity of newborn K(Ca) channels may be due to a reduced beta-subunit-to-alpha-subunit ratio. CO activation of K(Ca) channels was Ca(2+) dependent. CO increased open probability 3.7-fold with 10 microM free Ca(2+) at the cytosolic membrane surface but only 1.1-fold with 300 nM Ca(2+). CO left shifted the current-voltage relationship of cslo-alpha currents expressed in HEK-293 cells, increasing currents 2.2-fold at +50 mV. In summary, data suggest that in newborn arteriole smooth muscle cells, CO activates low-affinity K(Ca) channels via a direct effect on the alpha-subunit that increases apparent Ca(2+) sensitivity. The optimal tuning by CO of the micromolar Ca(2+) sensitivity of K(Ca) channels will lead to preferential activation by signaling modalities, such as Ca(2+) sparks, which elevate the subsarcolemmal Ca(2+) concentration within this range.