Axon Instruments Patch-Clamp Amplifiers

What is the best amplifier for doing slice recording?

MultiClamp 700B amplifier is the best fit for your application. It comes with two headstages and is ideal for both voltage-clamp and current-clamp recording.

Is it possible to switch between voltage and current clamp mode automatically in the MultiClamp 700B amplifier?

Yes, it can be done. The auto mode switching feature in the MultiClamp 700B amplifier allows automatic switching between voltage and current clamp mode or vice versa. The mode-switching checkbox on the Commander software is required to be enabled.

How do I get a “Fresh Start” for MultiClamp 700B Commander software?

On the top row of the MultiClamp 700B commander software, there is a list of icons. The fifth icon is the Reset to Program Defaults button. Click this button to restore the default settings for MultiClamp 700B Commander software.

The overload light illuminates on my amplifier when the pipette is immersed into the bath solution. What should I do?

The first thing to try is to replace the grounding cable/electrode or the bath reference electrode pellet/wire. If you use an agar bridge as the grounding/reference electrode, replace it with a fresh one. Second, clean the electrode holder. Disassemble the electrode holder, rinse all parts in distilled water several times and dry all holder parts thoroughly and reassemble.

What is liquid junction potential? How does it form in a patch clamp experiment? Should it be corrected or not?

When two solutions having different ionic concentrations and mobilities are in contact, a liquid junction potential (LJP) is formed between these two solutions. This happens when the patch pipette comes into contact with the bath solution. When the patch pipette is first inserted in the bath, there are voltage offsets that are corrected by the amplifier when the current is zeroed (i.e., in voltage-clamp mode). The offsets consist of LJPs and potential differences between solid electrodes and the solutions they are in contact with.

After achieving a high resistance seal (gigaseal) with the membrane, the pipette solution is effectively no longer in direct contact with the bath solution. Thus, its LJP disappears, but its compensating amplifier offset remains. Therefore, the LJP should be taken into consideration for correction or not. How large the liquid junction potential between two solutions depends on the difference in ionic concentration and mobilities. If it is very small, it might be neglected and not be corrected. However, if it is a large value, uncorrected LJP might affect accurate measurements, such as the IV plot and reversal potential. It is absolutely required to be corrected.