Intracellular electrode

The electrode is measuring the resting potential of a cell whose membrane contains only open K+ channels.

As the seal resistance Rs increases, the measurement approaches the value of EK .

 

 

For the case of patch recording, currents through the seal do not distort the measured voltage or current, but they do add to the current noise.

Current noise can be analyzed as:

* Johnson noise of a conductor, which is the thermal noise that increases with the conductance,

or

* Simple statistics: If a current of N ions/ms passes through an open channel, then the current will fluctuate from one millisecond to the next with a standard deviation N. These fluctuations produce noise on the single-channel recorded traces. If an additional current is flowing in parallel through the seal, it causes an increase in the standard deviations.

 

 

For instance, if the current through the seal is ten-fold larger than through the channel, then the statistical fluctuations in current flow produced by the seal are 316% larger than they would be for a "perfect" seal.

 

In a patch recording, currents through the seal also flow through the measuring circuit, increasing the noise on the measured current.