BIPN140 Lecture 4

BIPN140 Lecture 4 - Lecture 4 BIPN140 Combinations of Ion...

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Lecture 4 October 5, 2010 BIPN140 Chapter 3 Combinations of Ion Currents, I Relationship of microscopic and macroscopic currents I =i x N x Popen How do you record Na currents selectively? Summing many recordings of the same single channel – the ensemble average is a miniature whole cell current, but composed of the activity of a single channel Activation often leads to inactivation: loss of response to sustained stimulus Inactivation at the level of i Na and I Na Contrast with i K and I K Goal: Description of the Action Potential Currents Time course of G Na , G K, I Na , I K , and V m Rest, Threshold, Peak, Trough of Afterpotential I Na = -I K V rest depends on [K + ] o , ~58 mV per decade change in [K + ] o Height of AP depends on [Na + ] o, ~58 mV/decade change in [Na + ] o Voltage Clamp The giant squid axon, J Z Young Conductance change, K.C. Cole In real APs, Gs change as V m changes, A complex problem The voltage clamp, V m =V command ( V c) The injected current, I i , necessary to keep V
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BIPN140 Lecture 4 - Lecture 4 BIPN140 Combinations of Ion...

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