Lecture 2 - NPB113 Electrophysiology 2-1 Topics Ion Channel...

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January 7, 2010 1 NPB113 Electrophysiology 2-1 Topics Ion Channel Activation in Action Potential Generation Purkinje Fiber & Ventricular Muscle Cell Rectification of K Channel Conductance – affect on rate of depolarization and repolarization SA Nodal Pacemaker Cell AV Nodal Cell ANS Affects on SA Nodal Pacemaker Cell Action Potential ANS Affects on AV Nodal Cell Action Potential
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January 7, 2010 2 NPB113 Electrophysiology 2-2 Ionic Generation of Purkinje Fiber AP 4 0 1 2 3 4 Phase 4 – RMP Inward Current I b Outward Current I K1 (Inward Rectified) I Na/K Exchanger Questions : 1. Does inward or outward current dominate membrane potential? 2. Why is the membrane potential closer to the E K than to the E Na ? - 80 mv +30mv
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January 7, 2010 3 NPB113 Electrophysiology 2-3 Ionic Generation AP Phase 0 – upstroke AP Inward Current I FNa dominant inward current. Initial and fully activated -70 mv. I Ca T Fast Ca current Initial activation at -40 mv Much slower activation than I FNa I Ca L Begin activation of slow Ca Current Fully Activated Phase 2 Outward Current I kr about -50 mv. (outward rectified) I Ks about 0 mv + with incr Ca in. (outward rectified) I to -10mv + incr Ca in . (outward rectified) Primary affect at Phase 1. 4 0 1 2 3 4 - 85 mv +30mv
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January 7, 2010 4 NPB113 Electrophysiology 2-4 Ionic Generation AP Phase 0, cont. I FNa inactivated peak of Phase 0 with closure of h, inactivation, gates. Dominant inward fast Na current terminated.
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This note was uploaded on 04/09/2010 for the course NPB npb 113 taught by Professor Goldberg during the Spring '10 term at UC Davis.

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Lecture 2 - NPB113 Electrophysiology 2-1 Topics Ion Channel...

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