Figure 1.
Coexpression of ASIC2b with ASIC1a changes the pharmacology of proton-gated currents. A, Representative trace of acid-evoked current from Xenopus oocytes expressing mouse ASIC1a, ASIC2b, or both. Bars above the trace show application of acidic solution (pH indicated). B, Representative traces showing the effects of extracellular TEA and barium ions on ASIC1a (top) and ASIC2b/1a (bottom) current in oocytes. ASIC current was evoked by application of pH 4.5 (white bars) from a holding pH of 7.9. Black bar indicates application of extracellular solution containing 10 mm TEA or Ba2+ before and during acid application. C, Quantification of TEA or Ba2+ inhibition. % Inhibition, Difference in current amplitude in the presence of TEA or barium compared with control current amplitude. **p < 0.01, compared with the corresponding ASIC1a group; +p < 0.05, compared with the corresponding ASIC2a/1a group with ANOVA (1-way). n = 3–6 for ASIC1a, n = 4–7 for ASIC2b/1a, and n = 3–5 for ASIC2a/1a. Note that results with ASIC1a are not significantly different from zero. D, E, Concentration dependence of TEA (D) and Ba2+ (E) inhibition of ASIC current. TEA or Ba2+ was added at the indicated concentrations, and data were normalized to pH 4.5-evoked control current as before. n = 4 for ASIC1a, n = 5 for ASIC2b/1a, and n = 5 for ASIC2a/1a. F, G, Voltage dependence for TEA (F) and Ba2+ (G) inhibition of ASIC2b/1a current. Current was evoked in the presence of 10 mm TEA, Ba2+, or control at the indicated holding potentials, and % Inhibition was determined as before (n = 3–4). Error bars are the SEM.