Fig. 9.

Effect of psalmotoxin 1 (PcTx1), an ASIC1a inhibitor and ASIC1b activator, on H⁺-induced currents in isolated cerebral VSMCs. A: representative traces of acid-induced current response to preconditioning with 100 nM PcTx1 for 30 s. Traces of VSMCs (24 out of 45) that responded to the control H⁺ stimulus are shown in a and b. In these cells, inward currents were either inhibited (a) or enhanced (b). Currents were enhanced (19/45) nearly four times as often as they were inhibited (5/45). Traces of VSMCs (21/45) that did not respond to an initial extracellular H⁺ stimulus are shown in c and d. In these cells, PcTx1 had no effect (c) or resulted in activation of currents (d). Currents were activated (15/45) nearly twice as often as they were unaffected (6/45). Thus, PcTx1 predominantly potentiated H⁺-gated currents in VSMCs. B: group data summarizing the effect of PcTx1 on the change in peak current density. C and D: in the VSMCs where PcTx1 enhanced or activated current, PcTx1 increased total current density relative to control (∫PcTx1_pH6.0/∫control_pH6.0) (C) and delayed desensitization (τ_decay, decay time constant) of the inward current (D).