Fig. 11. 4-AP abolishes the inhibitory action of ENpa on the ACh-induced contraction. (A) Action of 10^–7 mol l^–1 ENpa on the contraction in the absence (Ai) or presence (Aii) of 10^–3 mol l^–1 4-AP. 3 x10^–6 mol l^–1 ACh was applied for 20 s at arrows. (B) Inhibitory action of ENpa in the absence [(–)4-AP] or the presence [(+)4-AP] of 10^–3 mol l^–1 4-AP (N=4). Statistical significance was assessed by Student's t-test.