de Weille J, Bassilana F
Institut de Pharmacologie Cellulaire et Moléculaire, CNRS UPR411, 06540, Valbonne, France.
Brain Res. 2001 May 11;900(2):277-81. doi: 10.1016/s0006-8993(01)02345-9.
The early H(+)-induced current in the embryonic spinal cord neurone depends on extracellular Ca(2+) for its function. We have studied the Ca(2+)-dependence of homo- and heteromultimeric acid-sensing ion channels (ASICs) expressed in Cos cells. It was found that single-channel conductance of both the ASIC2a and the ASIC1a channel is reduced at membrane potentials more negative than -40 mV by elevated extracellular Ca(2+). Due to this effect on unitary currents, the macroscopic ASIC2a peak current at -60 mV decreases gradually with rising extracellular Ca(2+) concentration. In addition, the macroscopic ASIC1a current is very small at low extracellular Ca(2+) and increases with rising Ca(2+) up to 5 mM before decreasing again at still higher concentrations of extracellular Ca(2+).
胚胎脊髓神经元中早期H⁺诱导电流的功能依赖于细胞外Ca²⁺。我们研究了在Cos细胞中表达的同聚体和异聚体酸敏感离子通道（ASICs）对Ca²⁺的依赖性。结果发现，细胞外Ca²⁺浓度升高时，ASIC2a和ASIC1a通道的单通道电导在膜电位比-40 mV更负时会降低。由于这种对单位电流的影响，-60 mV时宏观ASIC2a峰值电流会随着细胞外Ca²⁺浓度的升高而逐渐降低。此外，在低细胞外Ca²⁺浓度下，宏观ASIC1a电流非常小，随着Ca²⁺浓度升高至5 mM，电流增加，而在更高的细胞外Ca²⁺浓度下又再次降低。
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