Effect of STZ treatment on total, cholinergic, and purinergic contraction in wild-type and M2 KO intact bladders. Total (a), cholinergic (b), and purinergic (c) responses were measured at 8 to 9 weeks after STZ treatment and after 20 to 24 weeks (d, e, f, respectively). Mean values ± S.E.M. from 3 to 10 experiments are shown. Significantly different from vehicle (*, P < 0.05, **, P < 0.001).