Perin P, Masetto S, Martini M, Rossi M L, Rubbini G, Rispoli G, Guth P, Zucca G, Valli P
Department of Cell and Molecular Physiological and Pharmacological Sciences, Section of General Physiology and Cell Biophysics, University of Pavia, viale Forlanini 6, 27100 Pavia, Italy.
Hear Res. 2001 Feb;152(1-2):67-76. doi: 10.1016/s0378-5955(00)00237-9.
In the present work we studied the regional expression of voltage-dependent Ca channels in hair cells from the frog semicircular canals, employing whole-cell patch-clamp on isolated and in situ hair cells. Although Ca channels are thought to play a major role in afferent transmission, up to now no data were available regarding their distribution in vestibular organs. The problem appears of interest, especially in the light of recent results showing the presence of multiple Ca current components in semicircular canal hair cells. Our data suggest the presence, in all regions of the crista ampullaris, of two classes of cells, one displaying an inactivating Ca current (R1) and one lacking it. In the former cells, Ca current amplitude decreased from the central to the peripheral zone (the maximal currents being observed in the intermediate zone). Only L-type and R2 current components displayed regional differences in expression, whereas the size and properties of R1, although variable among cells, were not regionalized. However, in cells lacking R1, Ca current amplitudes were similar regardless of cell shape and location. The possible contributions of this Ca current distribution to afferent discharge properties are discussed.
在本研究中，我们采用全细胞膜片钳技术对离体和原位的青蛙半规管毛细胞进行研究，以探讨电压依赖性钙通道在这些毛细胞中的区域表达情况。尽管钙通道被认为在传入神经传递中起主要作用，但迄今为止，关于它们在前庭器官中的分布尚无数据。鉴于最近的研究结果表明半规管毛细胞中存在多种钙电流成分，这个问题显得尤为有趣。我们的数据表明，在壶腹嵴的所有区域都存在两类细胞，一类表现出失活的钙电流（R1），另一类则没有。在前一类细胞中，钙电流幅度从中央区域到周边区域逐渐减小（最大电流出现在中间区域）。只有L型和R2电流成分在表达上存在区域差异，而R1的大小和特性虽然在不同细胞之间有所变化，但不存在区域化现象。然而，在缺乏R1的细胞中，无论细胞形状和位置如何，钙电流幅度都相似。我们还讨论了这种钙电流分布对传入放电特性的可能贡献。
