18 • Tutorials
MultiClamp 700A Theory and Operation, Copyright 2000, 2001 Axon Instruments, Inc.
A repetitive pulse appears on the Membrane Potential output. The amplitude of
the Tuning pulse is 1 nA. The amplitude of the Membrane Potential output pulse
is 10 mV, which corresponds to 10 mV at the default gain of 1 V/V (shown under
Scaled Output in the Output Signals section). Therefore, the resistance of the
model electrode is calculated from Ohm’s Law to be R = V/I = 10 mV/1 nA =
10 MΩ. Alternatively, the resistance can be directly displayed by checking the
Resistance checkbox under the Channel 1 meters.
5. Try changing the Tuning amplitude and frequency by using the glider control with
the mouse, as described in Tutorial 1, Step 6.
Tutorial 3 – Giga Seal Configuration
1. Set up the MultiClamp 700A and the MultiClamp Commander as in Steps 1-3 of
Tutorial 1, except that the PATCH connector on the model cell should be plugged
into the headstage of the MultiClamp 700A. This connects a 10 GΩ resistor to
ground, simulating a gigaseal.
2. One of the advantages of a gigaseal is that the recording noise is dramatically
reduced, enabling single-channel measurements. However, to facilitate single-
channel recording it is necessary to change the feedback resistor in the headstage
of the patch clamp amplifier. For illustration, look at the Channel 1 Scaled Output
after turning up the vertical gain on the oscilloscope. The noise on Scaled Output
should be about 5 mV peak-to-peak (p-p), which corresponds to 10 pA (p-p) with
the Scaled Output gain set to 0.5V/nA (default value). 10 pA is too noisy for most
single-channel recording.
3. Press the Options toolbar button at the top of the MultiClamp Commander.
Figure 2.10
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