Copyright e The McGraw-Hill Companies, Inc. Permission required for reproduction or display Phase 3(repolarization Inactivation of ca2+ channel Outward K+ current dominates 8g s The repolarizing k+ current turns on slowly 0.15 0.30 Time(s) ■ Phase4 100 Sarcolemmal Cat pump Nat-K pump EE Pca2+ In conducting system, the electrical diastolic phase 0.1 0.15 0.30 Time(s)◼ Phase 3 (repolarization) Inactivation of Ca2+ channel Outward K+ current dominates * The repolarizing K+ current turns on slowly. ◼ Phase 4 Sarcolemmal Ca2+ pump Na+ -K + pump * In conducting system, the electrical diastolic phase 3 4 21