GMQ hydrochloride (NSC-403387 hydrochloride) is a potent and selective acid-sensing ion channel (ASIC) modulator. It activates ASIC3 channels under neutral pH and blocks acid-induced maximal peak current.

Addition of GMQ to pituitary GH3 cells raised the amplitude of Ca2+-activated K+ currents (IK(Ca)), which was reversed by verruculogen or PF1022A, but not by TRAM-39.?Under inside-out current recordings, addition of GMQ into bath enhanced the probability of large-conductance Ca2+-activated K+ (BKCa) channels with an EC50 value of 0.95 M. The activation curve of BKCa channels during exposure to GMQ shifted to a lower depolarized potential, with no change in the gating charge of the curve;?however, there was a reduction of free energy for channel activation in its presence.?As cells were exposed to GMQ, the amplitude of ion currents were suppressed, including delayed rectifying K+ current, voltage-gated Na+ and L-type Ca2+ currents.?In Rolf B1.T olfactory sensory neuron, addition of GMQ was able to induce inward current and to suppress peak INa.