Cardiac Nat Channes Almost identical to nerve nat channels (structurally and functionally very fast opening(as in nerve) has inactivation state(as in nerve) NOT Tetrodotoxin sensitive Expressed only in non nodal tissue Responsible for initiating and propagating the action potential in non nodal cells 12
12 Cardiac Na+ Channels ➢ Almost identical to nerve Na+ channels (structurally and functionally) ➢ very fast opening (as in nerve) ➢ has inactivation state (as in nerve) ➢ NOT Tetrodotoxin sensitive ➢ Expressed only in non nodal tissue ➢ Responsible for initiating and propagating the action potential in non nodal cells
+20 2 0 3 90 300 t(msec) 13
13 t (msec) -90 0 +20 0 300 0 1 2 3 4
Inward Rectifier (K1 Structure Note: No voltage sensor P-Region Extracellular Fluid M1 M2 membrane Inside H2N HO2C 14
14 Inward Rectifier (Ik1) Structure M1 M2 HO2C H2N Inside P-Region Extracellular Fluid membrane Note: No “voltage sensor
Inward rectifier Channels E 120-100 20 Vm(mv) 15
15 Inward Rectifier Channels -120 -100 -80 -60 -40 -20 0 20 40 60 Current Vm (mV) 0 Ek
Inward Rectification 98 V K 16
16 Inward Rectification Extracellular solution Intracellular Solution --80 mV 30 mV K+ K+ Mg2+ K+ K+ K+ K+ K+ Mg2+ K+ K+