Effects of Arginine and Its Metabolites on ASIC3 Channels. (A) Chemical structure of GMQ, arcaine (ARC), arginine and its metabolites. (B) Summary (periphery) of and sample traces (inset) showing the effects of compounds on ASIC3 channels at neutral pH. Each compound was applied at a concentration of 1 mM. The first above trace represents the baseline level without drug application (zero level), followed by the current induced by AGM, ARC, and GMQ, respectively. Data points are means ± S.E.M. of four to six measurements normalized to GMQ-induced response. **p < 0.001 vs. baseline level.