The calcium-activated potassium channels of turtle hair cells.
The calcium-activated potassium channels of turtle hair cells.
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DOI：
10.1085/jgp.105.1.49
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发表时间：
1995-01
期刊：
影响因子：
--
通讯作者：
Fettiplace R
中科院分区：
文献类型：
--
作者：
Art JJ;Wu YC;Fettiplace R
决定甲鱼耳蜗毛细胞电共振频率的一个主要因素是钙激活的钾电流的时间过程(Art，J.J.和R.Fettiplace)。1987年。生理学杂志。385：207-242)。我们通过从细胞内向外记录单个钙激活的钾通道，验证了这一时间过程由钾通道动力学决定的概念。毛细胞的共振频率是根据它与毛束尺寸的已知相关性来估计的。所有细胞都有BK通道，其相似的单位电导约为320ps，但平均开放时间不同，为0.25-12ms。平均单通道电流在-50 mV处的松弛时间常数在0.4~13ms之间变化，并与毛束高度相关。时间常数的大小和电压依赖关系符合宏观K(Ca)电流的预期行为，因此其速度可能受到通道动力学的限制。所有BK通道对钙的敏感性相似，钙在+50 mV和-50 mV时分别产生约2微米和12微米的半最大激活。我们从全细胞K(Ca)电流的电压依赖关系估计，当细胞内钙升高到50微米时，BK通道可能在-35 mV被完全激活。有时观察到BK通道在慢门和快门模式之间切换，这增加了在不同毛细胞中观察到的BK通道的动力学范围反映了一种共同的通道蛋白的可能性，其动力学受一种未知的细胞内因素调节。膜片上还含有30个pS-SK通道，在-50 mV时，该通道对钙的敏感性约为BK通道的5倍。SK通道可能是毛细胞传出刺激产生的抑制性突触电位的基础。
A major factor determining the electrical resonant frequency of turtle cochlear hair cells is the time course of the Ca-activated K current (Art, J. J., and R. Fettiplace. 1987. Journal of Physiology. 385:207- 242). We have examined the notion that this time course is dictated by the K channel kinetics by recording single Ca-activated K channels in inside-out patches from isolated cells. A hair cell's resonant frequency was estimated from its known correlation with the dimensions of the hair bundle. All cells possess BK channels with a similar unit conductance of approximately 320 pS but with different mean open times of 0.25-12 ms. The time constant of relaxation of the average single- channel current at -50 mV in 4 microM Ca varied between cells from 0.4 to 13 ms and was correlated with the hair bundle height. The magnitude and voltage dependence of the time constant agree with the expected behavior of the macroscopic K(Ca) current, whose speed may thus be limited by the channel kinetics. All BK channels had similar sensitivities to Ca which produced half-maximal activation for a concentration of approximately 2 microM at +50 mV and 12 microM at -50 mV. We estimate from the voltage dependence of the whole-cell K(Ca) current that the BK channels may be fully activated at -35 mV by a rise in intracellular Ca to 50 microM. BK channels were occasionally observed to switch between slow and fast gating modes which raises the possibility that the range of kinetics of BK channels observed in different hair cells reflects a common channel protein whose kinetics are regulated by an unidentified intracellular factor. Membrane patches also contained 30 pS SK channels which were approximately 5 times more Ca-sensitive than BK channels at -50 mV. The SK channels may underlie the inhibitory synaptic potential produced in hair cells by efferent stimulation.
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DOI：
10.1085/jgp.88.3.293
发表时间：
1986-09
期刊：
The Journal of general physiology
影响因子：
--
作者：
Hess P;Lansman JB;Tsien RW
通讯作者：
Tsien RW
影响因子：
5.5
作者：
CRAWFORD, AC;FETTIPLACE, R
通讯作者：
FETTIPLACE, R
影响因子：
64.8
作者：
ASHMORE, JF;MEECH, RW
通讯作者：
MEECH, RW
DOI：
10.1016/0304-4165(87)90102-4
发表时间：
1987-08-13
期刊：
BIOCHIMICA ET BIOPHYSICA ACTA
影响因子：
--
作者：
HARRISON, SM;BERS, DM
通讯作者：
BERS, DM
影响因子：
5.5
作者：
ART, JJ;FETTIPLACE, R
通讯作者：
FETTIPLACE, R