Bauer B
Acta Ophthalmol (Copenh). 1978 Apr;56(2):270-81. doi: 10.1111/j.1755-3768.1978.tb01353.x.
The in vitro release of radioactivity by light from rabbit retina was studied after intravitreal injection of [3H]GABA (gamma-aminobutyric acid). The site of uptake of [3H]GABA into the retina after intravitreal injection was checked by autoradiography and was localized at 2 h after the injection mainly in glia but at 4 h in amacrine cells and some ganglion cells. If the retina loaded with [3H]GABA was stimulated by light flashes the efflux of radioactivity increased significantly. Chromatographic analysis of the superfusate demonstrated that [3H]GABA was released by light stimulation. However, the efflux was not elicited by constant light, and was abolished in a medium containing 20 mM Mg++ and 0.2 mM++. When the metabolism of GABA was inhibited by amino-oxyacetic acid, light flashes no longer increased the efflux of radioactivity significantly. No light-evoked release of radioactivity could be demonstrated from glia. Pentobarbitone inhibited the spontaneous efflux and prior anaesthetization with pentobarbitone abolished the light-evoked release. These results support the view that GABA is a retinal neurotransmitter in the rabbit.
在玻璃体内注射[3H]γ-氨基丁酸（GABA）后，研究了光对兔视网膜放射性物质的体外释放情况。通过放射自显影检查玻璃体内注射后[3H]GABA在视网膜中的摄取部位，注射后2小时主要定位于神经胶质细胞，4小时定位于无长突细胞和一些神经节细胞。如果用闪光刺激加载有[3H]GABA的视网膜，放射性物质的流出会显著增加。对超滤液的色谱分析表明，[3H]GABA是由光刺激释放的。然而，持续光照不会引发流出，并且在含有20 mM Mg++和0.2 mM++的培养基中流出被消除。当GABA的代谢被氨基氧乙酸抑制时，闪光不再显著增加放射性物质的流出。神经胶质细胞未表现出光诱发的放射性物质释放。戊巴比妥抑制自发流出，用戊巴比妥预先麻醉可消除光诱发的释放。这些结果支持GABA是兔视网膜神经递质的观点。
