1. Resting potential, Measurement of Ion Movement
Lecture 2
Resting potential, Measurement of Ion Movement
Membrane Potential in Excitable Cells 1:
Voltage-gated channels & the basis of the Action Potential

2. Some useful physical constants
From Bertil Hille, Ion Channels of Excitable Membranes, 3rd edition

3. Driving Force: Vm - Ex I = g Vm IK = gK (Vm – EK)
EK = 61 log (150/ 150) = 0 mV
EK = 61 log (150/ 45) = + 32 mV
EK = 61 log (30/ 150) = mV

4. gK (VR – EK) = -gNa (VR – ENa)
At the resting membrane potential the individual ionic currents sum up to zero
I = g V
IK = gK (Vm – EK)
INa = gNa (Vm – ENa)
At rest IK = -INa
gK (VR – EK) = -gNa (VR – ENa)
If gK:gNa = 5, solve for VR
VR = -64 mV
VR = (ENagNa/gK+gNa) +
(EKgK/gK+gNa)

5. Voltage Clamp

6. The Patch-clamp technique

7. Patch clamping a neuron

8. Recordings of a single cardiac K channel and its current-voltage characteristics

9. Recordings of a whole-cell CNG current and its I-V characteristics

10. A model of a voltage-gated channel protein

11. The depolarization-induced biphasic current of squid giant axons

12. Inward sodium and outward currents

13. Sodium and Potassium whole-cell currents