Voltage Clamp

Patch Clamp Applications

Evidence that potassium is primarily responsible for the RMP.

Neuron membrane is at rest

Now let’s look at the responses of a neuron to various stimuli

Evidence that sodium is responsible for inward current during depolarization phase of the action potential. Use of the voltage clamp to measure current.

Normal membrane current during the action potential.

Membrane current when there is no Na contribution.

Combine these two curves

The bottom curve is a subtraction of the other two, showing the effect of sodium current.

Another experiment demonstrates the same conclusion, again using the voltage clamp.

These curves are all “normal” curves during action potential, with the membrane held at various voltages by the voltage clamp.

E Na+ ~ 50 mV in this experiment

This diagram is similar to Fig. 5.21

The remainder of this presentation will focus on the actions and effects of synapses