Mechanisms of acetylcholine -increase K& decrease Ca permeability K+ outward↑,MRP|↑, phase4 spontaneous depolarization \, autorhythmicity l Inhibition of Caz+ channel, phase 0 amplitude velocity \, conductivity l Ca2+ influx V, [Ca2+]V, contractility tMechanisms of acetylcholine —increase K+ & decrease Ca2+ permeability • K+ outward , |MRP| , phase 4 spontaneous depolarization , autorhythmicity  • Inhibition of Ca2+ channel, phase 0 amplitude & velocity , conductivity  • Ca2+ influx , [Ca2+ ] i , contractility 