action potentials in whole cell mode

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Golden ball
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action potentials in whole cell mode

Hi
I want to record cardiac action potentials using whole cell mode. Should I compensate series resistance? Comparing the conditions with or without series resistance compensation, the amplitude of action potentials can be different?
Thank you.

Guy Sovak
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Hi there,

Hi there,
I will ask someone I know and get you the answer ASAP
Guy

Guy Sovak
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Did you got your answer?

Did you got your answer?

Fraser Moss
Fraser Moss's picture
When you are recording action

When you are recording action potentials, you will be using current-clamp to measure voltage. In the current clamp circuit there is no such thing as series resistance (Rs) compensation. Rs compensation is for when you are using voltage-clamp and it compensates for the voltage lost over the series resistance (Ohms law V=IR).

When you are in current clamp you will need to apply a "bridge balance". When you step to a particular current you generate a potential difference due to the series resistance and the membrane resistance. The bridge balance subtracts the voltage
attributable to the microelectrode from your trace.

Fraser Moss
Fraser Moss's picture
you should read this old

you should read this old review

Trends Neurosci. 1996 Dec;19(12):530-4

Action potentials recorded with patch-clamp amplifiers: are they genuine?
Magistretti J, Mantegazza M, Guatteo E, Wanke E.

Dept of Experimental Neurophysiology, National Neurologic Institute, C. Besta, Milano, Italy.

A growing number of experimental studies have used patch-clamp amplifiers (PCAs) in the current-clamp (CC) mode to investigate classical excitability. In this paper we show that the measurements obtained in this way are affected by errors due to the electronic design of the PCA input section. We present experimental evidence of such errors, and demonstrate that they derive from PCA current absorption. Moreover, we propose a new PCA input-circuit configuration for the CC mode, which is suitable for accurately recording physiological voltage signals and is perfectly compatible with the standard voltage-clamp mode.

PMID: 8961481 [PubMed - indexed for MEDLINE]

Golden ball
Golden ball's picture
Thank you for your reply.

Thank you for your reply.
I will read the paper you sugested to read. Nice to know such information.

Fraser Moss
Fraser Moss's picture
I refer you to the review

I refer you to the review that I posted earlier in this thread.

If you apply a proper bridge balance in the current clamp mode then any voltage attributable to the electrode rather than the sample should be eliminated.