Coexpression of ASIC2a with ASIC1a generates increased currents.

<p><i>A</i>, Representative acid-evoked currents generated by pH 4 application to CHO cells transfected with the indicated ASIC subunits. Coexpressed ASICs were expressed at half the normal amount to keep total ASIC cDNA constant. The bar above each current trace represents the time that the perfusing solution was rapidly changed from pH 7.4 to 4. <i>B</i>, pH-dose response curves for activation of cells expressing ASIC1a, ASIC2a, or coexpressing ASIC1a and ASIC2a. Data were acquired by stepping from pH 7.4 to the indicated test solution, and are normalized to the maximal currents (<i>n</i> ≥6). Lines are fits of the Hill equation. <i>C</i>, Superimposed pH 5-evoked currents from cells expressing ASIC1a or coexpressed ASIC1a and -2a (vertical scale bar: 3.66 nA ASIC1a and 5 nA coexpressed ASIC1a and -2a). To the right are the mean time constants (τ) of desensitization as measured from single exponential fits to the falling phase of currents evoked by pH 5 (<i>n</i> ≥8; *<i>P</i><0.01). <i>D</i>, Mean current densities evoked by pH 4 in cells expressing the indicated ASIC subunits (<i>n</i> ≥6; *<i>P</i><0.01 compared to ASIC1a expressed alone).