(A) Coptisine reversed ACh-induced contraction under PSS condition (n=6/6 mice). (B) Coptisine reversed ACh-induced contraction under Li-PSS condition (n=6/6 mice). (C) The bar graph showed the comparisons of forces at the baseline, contraction, relaxation from six experiments, respectively. *, P<0.05, **, P<0.01. (D) In Li-PSS solution, KB-R7943 partially reversed ACh-induced contraction (n=6/6 mice). (E) In Li-PSS medium, after coptisine reversed ACh-induced contraction, KB-R7943 could subsequently relax the mouse tracheal ring lower than the baseline (n=6/6 mice).