網膜の発生とCaチャネル

Retinogenesis and Ca channels

はじめに

　細胞内Caイオンは細胞増殖，神経突起の形態分化，細胞死あるいはシナプス可塑性などの神経回路の形成過程における重要な側面に関与する^1-3）。本稿では神経発生期の網膜を対象として，（1）電位依存性Caチャネル，（2）細胞内CaストアからのCaリリースについて述べ，とくに後者は神経発生期に顕著な応答であることから“発生期Ca動員系”（embryonic Ca mobilization system）^4）という概念を提唱したい。

The physiological properties of Ca channels during the early period of retinogenesis were studied in the embryonic chick retina. The whole neural retina was isolated from embryonic day 3 (E3) chick and loaded with a Ca“-sensitive fluorescent dye (Fura-2AM). The retinal cells were depolarized by the puff application of high-K+ solutions. Increases in intracellular Ca” concentrations were evoked by the depolarization through voltage-dependent Ca channels. The type of Ca channel was identified as L-type by the sensitivity to dihydropyridines.