Multirecording of Ca2+ signals from inner retinal neurons evoked by light stimulation of photoreceptors

AbstractWe simultaneously monitored changes of intracellular free Ca2+ concentration ([Ca2+]i) following different light stimuli from different inner retinal neurons of the turtle retina slice preparation. [Ca2+]i increased with an increase of the light stimulus intensity. Some of the cells also showed color opponent Ca2+ signals. 2-Amino-4-phosphonobutyric acid (APB) blocked in particular [Ca2+]i increases and picrotoxin enhanced the observed [Ca2+]i changes. These data support the idea that the observed [Ca2+]i changes result from light stimulation and subsequent retinal processing. Similar Ca2+ signals were observed when the release of Ca2+ from internal stores was blocked with caffeine and thapsigargin. These results indicate that retinal Ca2+ signals evoked by light stimulation depend to a large extent on voltage-dependent Ca2+ influx and might therefore reflect signal processing