Genetic ablation of caveolin-1 modifies Ca2+ spark coupling in murine arterial smooth muscle cells
Genetic ablation of caveolin-1 modifies Ca2+ spark coupling in murine arterial smooth muscle cells
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DOI：
10.1152/ajpheart.01226.2005
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发表时间：
2006-06-01
影响因子：
4.8
通讯作者：
Jaggar, Jonathan H.
中科院分区：
文献类型：
--
作者：
Cheng, Xiaoyang;Jaggar, Jonathan H.
l型，电压依赖性钙（Ca2+）通道，红嘌呤敏感Ca2+释放（RyR）通道和大电导Ca2+激活钾（K-Ca）通道组成一个调节平滑肌收缩性的功能单元。在这里，我们研究了小窝蛋白1 （cav-1）的基因消融是否会改变小鼠脑动脉平滑肌细胞中Ca2+火花到K-Ca通道的偶联以及电压依赖性Ca2+通道对Ca2+火花的调节。对照细胞（cav-1(+/+)）的肌膜中有大量的小泡，而cav-1缺陷细胞（cav-1(-/-)）的肌膜中没有小泡。Ca2+火花和瞬态K-Ca电流频率在cav-1（-/-）细胞中大约是cav-1（+/+）细胞的两倍。虽然电压依赖性Ca2+电流密度在cav-1（+/+）和cav-1（-/-）细胞中相似，地尔硫卓和Cd2+，电压依赖性Ca2+通道阻滞剂，在cav-1（+/+）细胞中将瞬态K-Ca电流频率降低到与对照组的55%相似，但没有改变cav-1（-/-）细胞中的瞬态K-Ca电流频率。此外，虽然在cav-1（-/-）细胞中K-Ca通道密度升高，但瞬态K-Ca电流幅值与cav-1（+/+）细胞相似。cav-1（-/-）细胞中较高的Ca2+火花频率不是由于细胞内Ca2+浓度升高、肌浆网Ca2+负荷或一氧化氮合酶活性升高所致。同样，Ca2+火花的振幅和扩散，激活瞬态K-Ca电流的Ca2+火花的百分比，火花与瞬态K-Ca电流之间的振幅关系，以及K-Ca通道电导和表观Ca2+灵敏度在cav-1（+/+）和cav-1（-/-）细胞中相似。综上所述，cav-1烧蚀提高了Ca2+火花和瞬态KCa电流频率，减弱了产生Ca2+火花的电压依赖性Ca2+通道和RyR通道之间的耦合关系，提高了K-Ca通道密度，但不改变Ca2+火花对瞬态K-Ca电流的激活。这些发现表明，cav-1是脑动脉平滑肌细胞生理Ca2+火花和瞬态K-Ca电流调节所必需的。
L-type, voltage-dependent calcium (Ca2+) channels, ryanodine-sensitive Ca2+ release (RyR) channels, and large-conductance Ca2+-activated potassium (K-Ca) channels comprise a functional unit that regulates smooth muscle contractility. Here, we investigated whether genetic ablation of caveolin-1 (cav-1), a caveolae protein, alters Ca2+ spark to K-Ca channel coupling and Ca2+ spark regulation by voltage-dependent Ca2+ channels in murine cerebral artery smooth muscle cells. Caveolae were abundant in the sarcolemma of control (cav-1(+/+)) cells but were not observed in cav-1-deficient (cav-1(-/-)) cells. Ca2+ spark and transient K-Ca current frequency were approximately twofold higher in cav-1(-/-) than in cav-1(+/+) cells. Although voltage-dependent Ca2+ current density was similar in cav-1(+/+) and cav-1(-/-) cells, diltiazem and Cd2+, voltage-dependent Ca2+ channel blockers, reduced transient K-Ca current frequency to similar to 55% of control in cav-1(+/+) cells but did not alter transient K-Ca current frequency in cav-1(-/-) cells. Furthermore, although K-Ca channel density was elevated in cav-1(-/-) cells, transient K-Ca current amplitude was similar to that in cav-1(+/+) cells. Higher Ca2+ spark frequency in cav-1(-/-) cells was not due to elevated intracellular Ca2+ concentration, sarcoplasmic reticulum Ca2+ load, or nitric oxide synthase activity. Similarly, Ca2+ spark amplitude and spread, the percentage of Ca2+ sparks that activated a transient K-Ca current, the amplitude relationship between sparks and transient K-Ca currents, and K-Ca channel conductance and apparent Ca2+ sensitivity were similar in cav-1(+/+) and cav-1(-/-) cells. In summary, cav-1 ablation elevates Ca2+ spark and transient KCa current frequency, attenuates the coupling relationship between voltage-dependent Ca2+ channels and RyR channels that generate Ca2+ sparks, and elevates K-Ca channel density but does not alter transient K-Ca current activation by Ca2+ sparks. These findings indicate that cav-1 is required for physiological Ca2+ spark and transient K-Ca current regulation in cerebral artery smooth muscle cells.