Gain of Rod to Horizontal Cell Synaptic Transfer: Relation to Glutamate Release and a Dihydropyridine-Sensitive Calcium Current

摘要: We related rod to horizontal cell synaptic transfer glutamate release by rods. Simultaneous intracellular records were obtained from dark-adapted rod–horizontal pairs. Steady-state gain (defined as the ratio of voltage evoked same light stimulus) was 3.35 ± 0.60 for dim flashes and 1.50 0.03 bright flashes. Under conditions maintained illumination, there a measurable increment hyperpolarization each light-induced over full range voltages. In separate experiments we studied an intact, light-responsive photoreceptor layer, which inner retinal layers removed. Steady reduced monotonic function intensity; spectral sensitivity measures indicated that monitored The dependence on well fit activation high-voltage-activated, dihydropyridine-sensitive L-type calcium current, suggesting linear [Ca]i in terminal. A simple model incorporating this assumption accounts steady-state synapse.