FUNCTIONAL EXPRESSION AND PROPERTIES OF THE HUMAN SKELETAL-MUSCLE SODIUM-CHANNEL
FUNCTIONAL EXPRESSION AND PROPERTIES OF THE HUMAN SKELETAL-MUSCLE SODIUM-CHANNEL
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DOI：
10.1007/bf00585952
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发表时间：
1994-05-01
影响因子：
4.5
通讯作者：
HORN, R
中科院分区：
文献类型：
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作者：
CHAHINE, M;BENNETT, PB;HORN, R
制备编码成人骨骼肌Na+通道α亚基hSkM 1的全长脱氧核糖核酸互补（cDNA）构建体。从cRNA注射非洲爪蟾卵母细胞和瞬时转染tsA 201细胞的电生理记录的功能表达进行了研究。hSkM 1的Na+电流在卵母细胞中具有异常缓慢的失活动力学，但在哺乳动物细胞系中表达时具有相对正常的动力学。去极化过程中卵母细胞Na+电流的失活动力学用两个衰减指数的加权和拟合。快组分的时间常数与哺乳动物细胞中观察到的单一组分的时间常数相当。测量细胞外毒素河豚毒素（TTX）和α-芋螺毒素（mu CTX）对hSkM 1 Na+电流的阻断。卵母细胞中的IC 50值为25 nM（TTX）和1.2 μ M（mu CTX）。TTX的效力与大鼠同源物rSkM 1中观察到的效力相似，但mu CTX在hSkM 1中的效力低22倍，主要是由于hSkM 1中毒素解离速率较高。单通道记录从表达hSkM 1的卵母细胞的外向补丁获得。单通道电导为24.9 pS，与在卵母细胞中表达的rSkM 1所观察到的电导相似。
Full-length deoxyribonucleic acid, complementary (cDNA) constructs encoding the alpha-subunit of the adult human skeletal muscle Na+ channel, hSkM1, were prepared. Functional expression was studied by electrophysiological recordings from cRNA-injected Xenopus oocytes and from transiently transfected tsA201 cells. The Na+ currents of hSkM1 had abnormally slow inactivation kinetics in oocytes, but relatively normal kinetics when expressed in the mammalian cell line. The inactivation kinetics of Na+ currents in oocytes, during a depolarization, were fitted by a weighted sum of two decaying exponentials. The time constant of the fast component was comparable to that of the single component observed in mammalian cells. The block of hSkM1 Na+ currents by the extracellular toxins tetrodotoxin (TTX) and alpha-conotoxin (mu CTX) was measured. The IC50 values were 25nM (TTX) and 1.2 mu M (mu CTX) in oocytes. The potency of TTX is similar to that observed for the rat homolog rSkM1, but the potency of mu CTX is 22-fold lower in hSkM1, primarily due to a higher rate of toxin dissociation in hSkM1. Single-channel recordings were obtained from outside-out patches of oocytes expressing hSkM1. The single-channel conductance, 24.9 pS, is similar to that observed for rSkM1 expressed in oocytes.