Contribution of TRPC channels to SOCE in DRG neurons. All traces are representative calcium responses recorded using the Fura-2 ratiometric method. (A) Thapsigargin (Thaps, 1 μM, 7 min) evokes a biphasic SOCE response in cultured rat DRG neurons (control). The first phase reflects the release of calcium from ER stores while the second phase reflects the influx of extracellular calcium, upon calcium re-addition to the perfusion solution (calcium add-back protocol), via Orai and/or TRPC channels. The addition of the Orai blocker Gd3+ (1 μM, 7 min) resulted in a significant decrease of calcium influx by 50%, suggesting a possible role for other channels including TRPCs in the remaining response (n = 8-19, P < 0.05). (B) SKF96365 (30 μM), a general SOCE and TRPC blocker, completely blocks SOCE (n = 14-23, P < 0.0005). (C) Effect of SKF96365 on TRPC3 activity. Activation of TRPC3 with the DAG analog OAG (50 μM, 3 min), is significantly inhibited by SKF96365 (approximately 75%), indicating a major role for TRPC3 in the TRPC component of the thapsigargin-induced SOCE response observed in DRG neurons (n = 15-18, P < 0.01).