Blocking Ca2+ Signaling Pathways

Unless otherwise noted, drugs were dissolved in amphibian saline solution and superfused over the slice preparations. Cadmium (CdCl₂, 100–500 μM Sigma Chemicals) was used to block influx through Ca²⁺ channels. The ryanodine receptor blocker, dantrolene (10 μM), was used to block Ca²⁺ release from internal stores (Chen et al., 2014 (link)). Due to concerns about incomplete recovery after washout, each slice preparation was exposed to Cd²⁺ only once and then new slices were prepared for subsequent experiments. In some experiments, retinal slices were incubated with 100 μM EGTA-AM (Life Technologies) for 2 hours to increase intracellular Ca²⁺ buffering prior to starting electrophysiological recordings