I am trying to measure membrane potential using I=0 mode. I have configured my telegraphed instrument for the input channels, and still when I change to I=0 mode on the Multiclamp 700B controller, the units on my membrane test and on my Vm protocols are in pA. I have tried disabling the telegraphed instruments as somebody suggested, then changed the units in the lab bench, then switched back on telegraphing again, but this did not change the units when running my Vm protocol. Could anybody give me any suggestions?
Hi Thereza,
If you go to the Configure tab and then Lab bench, are you sure that the signal units for your input/outpout channels are correct? By default they are usually not and you have to define the units manually for each single channels you are using. Also make sure that you are not in "demo" mode.
Hi Norbert,
Thanks for your answer. I did go to lab bench and discovered that the signal units were wrong. The set-up manual says not to worry about this, because the units will be telegraphed from the Multiclamp 700B amplifier automatically, but I have been worrying about this. I think I've found the answer to my problem. There is a section in Multiclamp 700B just above where you change the Bessel filter setting. This can either say "Membrane potential" or "Membrane current" or a number of other things. I didn't realise that you could change this, but if you click on those words and drag the mouse up or down, you can change what the amplifier is measuring when in I=0 mode. I didn't think it made a lot of sense to be able to measure "membrane current" in I=0 mode, but for some reason that was the default setting in Multiclamp 700B. I changed it to "membrane potential" and now it works. I've been trying to sort this problem out for weeks! I hope this helps somebody else in the future.
Best wishes,
Theresa
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