LIGHT-EVOKED INOSITOL TRISPHOSPHATE RELEASE IN THE RAT RETINA IN-VITRO

Light exposure not only elicits a photic response but may also alter t he metabolism and functional properties of the retina. This may be evo ked by the stimulation of phospholipid derived second messenger system s. In this study, we investigated the light-evoked release of inositol 1,4,5-trisphosphate in the isolated rat retina in vitro by means of h igh performance liquid chromatography (HPLC) detection. After prelabel ling of isolated retinae with tritiated myo-inositol in darkness, they were exposed to no light or to white fluorescent light of 10,000 lux illuminance for 3,5 and 10 sec, respectively. We observed a 200% incre ase in the release of inositol 1,4,5-trisphosphate compared to basal v alues in darkness after 3 sec of light exposure with a decline after 5 sec and a return to basal values after 10 sec indicating a rapid brea kdown of inositol 1,4,5-trisphosphate. Our data confirm previous studi es in the amphibian retina and photoreceptors and demonstrate for the first time a light evoked inositol 1,4,5-trisphosphate release in the mammalian retina.