Huang Luoxiu, Li Lei
Department of Biological Sciences, University of Notre Dame, Notre Dame, Indiana 46556, USA.
J Neurosci Res. 2006 Aug 15;84(3):497-504. doi: 10.1002/jnr.20951.
We report a study on the characterization of voltage-activated calcium currents (I(Ca)) in retinal ganglion cells (RGCs) and the topographic distribution of RGCs that express different types of I(Ca) in zebrafish retinas. In acutely isolated zebrafish RGCs, both high-voltage-activated (HVA; peak activation potential +7.4 +/- 1.1 mV) and low-voltage-activated (LVA; peak activation potential -33.0 +/- 1.2 mV) I(Ca) were recorded. HVA I(Ca) were recorded in all of the tested RGCs, whereas LVA I(Ca) were recorded in approximately one-third of the tested cells. In RGCs that expressed both HVA and LVA I(Ca), the two currents were readily separated by depolarizing the cell membrane to different voltages from different holding potentials. Among RGCs that expressed LVA I(Ca), some cells expressed large LVA I(Ca) (up to 130 pA), whereas others expressed small LVA I(Ca) (approximately 20 pA). RGCs that expressed large and small LVA I(Ca) were designated as class I and class II cells, respectively, and RGCs that expressed only HVA I(Ca) were designated as class III cells. The topographic distribution of cell classes was similar in various areas of the retina. In the nasal-ventral retina, for example, class III cells outnumbered class I and class II cells by 10.8- and 2.6-fold, respectively. In the temporal and dorsal retinas, the density of class III cells slightly decreased, whereas the density of class I and class II cells increased. The differential expression of I(Ca) in RGCs may correlate with the development and function of the retina.
我们报告了一项关于斑马鱼视网膜中视网膜神经节细胞（RGCs）电压激活钙电流（I(Ca)）的特性以及表达不同类型I(Ca)的RGCs的拓扑分布的研究。在急性分离的斑马鱼RGCs中，记录到了高压激活（HVA；峰值激活电位+7.4±1.1 mV）和低压激活（LVA；峰值激活电位-33.0±1.2 mV）的I(Ca)。在所有测试的RGCs中都记录到了HVA I(Ca)，而在大约三分之一的测试细胞中记录到了LVA I(Ca)。在同时表达HVA和LVA I(Ca)的RGCs中，通过将细胞膜从不同的钳制电位去极化到不同电压，这两种电流很容易分离。在表达LVA I(Ca)的RGCs中，一些细胞表达大的LVA I(Ca)（高达130 pA），而另一些细胞表达小的LVA I(Ca)（约20 pA）。分别将表达大的和小的LVA I(Ca)的RGCs指定为I类和II类细胞，而仅表达HVA I(Ca)的RGCs指定为III类细胞。细胞类型的拓扑分布在视网膜的各个区域相似。例如，在鼻侧-腹侧视网膜中，III类细胞的数量分别比I类和II类细胞多10.8倍和2.6倍。在颞侧和背侧视网膜中，III类细胞的密度略有下降，而I类和II类细胞的密度增加。RGCs中I(Ca)的差异表达可能与视网膜的发育和功能相关。
