Monovalent cations contribute to T-type calcium channel (Cav3.1 and Cav3.2) selectivity.
Monovalent cations contribute to T-type calcium channel (Cav3.1 and Cav3.2) selectivity.
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单价阳离子有助于 T 型钙通道（Cav3.1 和 Cav3.2）选择性。
DOI：
10.1007/s00232-003-2017-9
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发表时间：
2003
期刊：
影响因子：
--
通讯作者：
Satin,J
中科院分区：
文献类型：
--
作者：
Delisle,BP;Satin,J
Low voltage-activated (LVA) Ca2+channels regulate chemical signaling by their ability to select for Ca2+. Whereas Ca2+is the main permeating species through Ca2+channels, Ca2+permeation may be modified by abundant intra- and extracellular monovalent cations. Therefore, we explored monovalent cation regulation of LVA Ca2+permeation in the cloned T-type Ca2+channels α1G (CaV3.1) and α1H (CaV3.2). In physiological [Ca2+], the reversal potential in symmetrical Li+was 19 mV in α1G and 18 mV in α1H, in symmetrical Cs+the reversal potential was 36 mV in α1G and 37 mV in α1H, and in the bi-ionic condition with Li+in the bath and Cs+in the pipette, the reversal potential was 46 mV in both α1G and α1H. When Cs+was used in the pipette, replacement of external Cs+with Li+(or Na+) shifted the reversal potential positive by 5–6 mV and increased the net inward current in α1G. Taken together the data indicate that in physiological [Ca2+], external Li+(or Na+) permeates more readily than external Cs+, resulting in a positive shift of the reversal potential. We conclude that external monovalent cations dictate T-type Ca2+channel selectivity by permeating through the channel. Similar to Li+, we previously reported that external [H+] can regulate T-type Ca2+channel selectivity. α1H’s selectivity was more sensitive to external pH changes compared to α1G. When Cs+was used in the pipette and Li+was used in the bath external acidification from pHo7.4 to 6.0 caused a negative shift of the reversal by 8 mV in α1H. Replacement of internal Cs+with Li+reduced the pH-induced shift of the reversal potential to 2 mV. We conclude that, similar to other external monovalent cations, H+can modify T-type Ca2+channel selectivity. However, in contrast to external monovalent ions that readily permeate, H+regulate T-type Ca2+channel selectivity by increasing the relative permeability of the internal monovalent cation.
