Unitary Ca2+ current through mammalian cardiac and amphibian skeletal muscle ryanodine receptor Channels under near-physiological ionic conditions.
Unitary Ca2+ current through mammalian cardiac and amphibian skeletal muscle ryanodine receptor Channels under near-physiological ionic conditions.
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在近生理离子条件下通过哺乳动物心脏和两栖动物骨骼肌兰尼碱受体通道的单一 Ca2+ 电流。
DOI：
10.1085/jgp.200308843
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发表时间：
2003-10
影响因子：
3.8
通讯作者：
Fill, M
中科院分区：
文献类型：
--
作者：
Kettlun, C;González, A;Ríos, E;Fill, M
来自哺乳动物心脏和两栖动物骨骼肌的Ryanodine受体（RyR）通道被整合到平面脂质双层中。在存在咖啡因（以最小化门控波动）的情况下，以0 mV记录SR管腔到细胞质方向的单一Ca2+电流。以20 mM腔内Ca2+为排他性载流子时测得的电流分别为4.00和4.07 pA，差异不显著。在哺乳动物和两栖动物通道中，在1 - 30 mM的腔内Ca2+浓度下记录的电流被生理[K+] （150 mM）和[Mg2+] （1 mM）以相同的比例（约55%）减弱。在两栖动物通道研究中发现了两个振幅，相差约35%，可能对应于α和β RyR亚型。在生理[Mg2+]， [K+]和管腔[Ca2+] （1 mM）中，Ca2+电流仅小于0.5 pA。将该值与Ca2+火花下的Ca2+通量进行比较，表明哺乳动物心脏和两栖动物骨骼肌中的火花是通过打开多个RyR通道产生的。此外，对称高浓度的Mg2+大大降低了10 mM Ca2+携带的电流（10 mM Mg2+时约40%），这表明高Mg2+可能通过抑制RyR门控和减少单一电流来减小火花。
Ryanodine receptor (RyR) channels from mammalian cardiac and amphibian skeletal muscle were incorporated into planar lipid bilayers. Unitary Ca2+ currents in the SR lumen-to-cytosol direction were recorded at 0 mV in the presence of caffeine (to minimize gating fluctuations). Currents measured with 20 mM lumenal Ca2+ as exclusive charge carrier were 4.00 and 4.07 pA, respectively, and not significantly different. Currents recorded at 1–30 mM lumenal Ca2+ concentrations were attenuated by physiological [K+] (150 mM) and [Mg2+] (1 mM), in the same proportion (∼55%) in mammalian and amphibian channels. Two amplitudes, differing by ∼35%, were found in amphibian channel studies, probably corresponding to α and β RyR isoforms. In physiological [Mg2+], [K+], and lumenal [Ca2+] (1 mM), the Ca2+ current was just less than 0.5 pA. Comparison of this value with the Ca2+ flux underlying Ca2+ sparks suggests that sparks in mammalian cardiac and amphibian skeletal muscles are generated by opening of multiple RyR channels. Further, symmetric high concentrations of Mg2+ substantially reduced the current carried by 10 mM Ca2+ (∼40% at 10 mM Mg2+), suggesting that high Mg2+ may make sparks smaller by both inhibiting RyR gating and reducing unitary current.
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影响因子：
3.4
作者：
BEST, PM;ABRAMCHECK, CW
通讯作者：
ABRAMCHECK, CW
DOI：
10.1085/jgp.115.2.139
发表时间：
2000-02
期刊：
The Journal of general physiology
影响因子：
--
作者：
González A;Kirsch WG;Shirokova N;Pizarro G;Stern MD;Ríos E
通讯作者：
Ríos E
影响因子：
3.4
作者：
Chen, DP;Xu, L;Eisenberg, B
通讯作者：
Eisenberg, B
影响因子：
4.8
作者：
Chen, W;Steenbergen, C;Murphy, E
通讯作者：
Murphy, E
影响因子：
56.9
作者：
CHENG, H;LEDERER, WJ;CANNELL, MB
通讯作者：
CANNELL, MB