Copyright o The McGraw-Hill Companies, Ine Permission required for reproduction or display. (a) ■ Phase1 a Transient outward current. to K+ current 0.15 □ activated at-20mV 口 opening for5~10ms 0.15
◼ Phase 1 Transient outward current, Ito K+ current activated at –20 mV opening for 5~10 ms
Copyright The McGraw-Hill Companies, Ine Permission required for reproduction or display. (a) ■ Phase2 0.15 Inward current 2 Outward current Time(s) (Ca2+& Na*) (K current) 0.15
◼ Phase 2 Inward current Outward current (Ca2+ & Na+ ) (K+ current)
Types of Ca2+ channels in cardiac cells (1)L-type(long-lasting)(Nowycky, 1985) (2) T-type(transient)(Nowycky, 1985)
Types of Ca2+ channels in cardiac cells: (1) L-type (long-lasting) (Nowycky, 1985) (2) T-type (transient) (Nowycky, 1985)
Ca2+ channels L-type T-type Duration of current long-lastin transient Activation kinetics Slower faster Inactivation kinetics slower faster Threshold high(-35mM) LoW( -60mV CAMP/CGMP-regulated Yes No Phosphorylation-regulated Yes No Openers Bay-K-8644 Blockers verapamil Tetramethrin nifedipine, diltiazem Ni2+ Inactivation by [Ca2+ Yes slight Patch-clamp recording run-down relatively stable
Ca2+ channels Duration of current long-lasting transient Activation kinetics slower faster Inactivation kinetics slower faster Threshold high (-35mV) Low (-60mV) cAMP/cGMP-regulated Yes No Phosphorylation-regulated Yes No Openers Bay-K-8644 - Blockers varapamil Tetramethrin nifedipine, diltiazem Ni2+ Inactivation by [Ca2+]i Yes slight Patch-clamp recording run-down relatively stable L-type T-type
Outward current(K* current) (1)inward rectifier K+ current (K1) (2) delayed rectifier K+ current (K)
Outward current (K+ current): (1) inward rectifier K+ current (IK1) (2) delayed rectifier K+ current (IK)