Rossi P, D'Angelo E, Magistretti J, Toselli M, Taglietti V
Institute of General Physiology, Pavia, Italy.
Pflugers Arch. 1994 Nov;429(1):107-16. doi: 10.1007/BF02584036.
Ca2+ currents play a crucial role during neuronal growth. In this paper we describe the development of Ca2+ currents using whole-cell patch-clamp recordings in granule cells of cerebellar slices obtained from 7- to 24-day-old rats. Granule cells expressed high-voltage-activated (HVA) Ca2+ currents in different proportions. The percentage of cells with a measurable HVA current, and the size of HVA current increased in parallel with granule cell maturation. At less than 14 days HVA currents consisted of a fast- and slow-inactivating component, while at more than 19 days only the slow-inactivating component remained. The fast-inactivating component had faster activation and inactivation kinetics, a more negative threshold for activation, and steeper steady-state inactivation than the slow-inactivating component. Nifedipine (5 microM) partially blocked both components. omega-Conotoxin (5 microM, omega-CgTx) blocked the slow-inactivating component rather selectively. These results indicate that HVA currents change their gating and pharmacological properties during development. Although the mechanism at the molecular level remains speculative, the developmental changes of the HVA current are relevant to the processes of granule cell maturation and excitability.
钙离子电流在神经元生长过程中起着至关重要的作用。在本文中，我们描述了利用全细胞膜片钳记录技术，对从7至24日龄大鼠获取的小脑切片颗粒细胞中钙离子电流的发育情况进行的研究。颗粒细胞以不同比例表达高电压激活（HVA）钙离子电流。可测量到HVA电流的细胞百分比以及HVA电流的大小与颗粒细胞的成熟程度平行增加。在14天以下时，HVA电流由快速失活和慢速失活成分组成，而在19天以上时，仅保留慢速失活成分。快速失活成分比慢速失活成分具有更快的激活和失活动力学、更负的激活阈值以及更陡峭的稳态失活。硝苯地平（5微摩尔）部分阻断了这两种成分。ω - 芋螺毒素（5微摩尔，ω - CgTx）相当选择性地阻断了慢速失活成分。这些结果表明，HVA电流在发育过程中改变了其门控和药理学特性。尽管分子水平的机制仍属推测，但HVA电流的发育变化与颗粒细胞成熟和兴奋性的过程相关。
