opyright e The McGraw-Hill Companies, Inc. Permission required tor reproduction or display 2 Phase 1 (rapid repolarization a Fast shut of nat channel a k*t current stays below the resting value 100 0.15 0.30 a Ca2+ channel starts to open ■ Phase2 10.0 a The long-lasting L-type Ca2 channel open and Ca2+ enters◼ Phase 1 (rapid repolarization)  Fast shut of Na+ channel  K + current stays below the resting value ◼ Phase 2 1 2  Ca2+ channel starts to open  The long-lasting L-type Ca2+ channel open and Ca2+ enters 19