132 • Reference Section
MultiClamp 700A Theory and Operation, Copyright 2000, 2001 Axon Instruments, Inc.
Zap
• Zap applies a large, brief voltage pulse to the electrode when in V-Clamp mode, to
facilitate breaking into a cell for whole-cell recording.
• Zap is triggered by pressing the
button in the V-Clamp pane.
The conventional method for rupturing a membrane patch to go to whole-cell
recording is to apply a pulse of suction. Sometimes this method damages the cell. Zap
provides an alternative method. It applies a large (1 V) voltage pulse that ruptures the
patch, presumably by causing dielectric breakdown of the membrane. The Zap
duration can be varied; it is best to use the minimum duration that is likely to achieve
the desired result, because too long a Zap could cause the seal resistance to deteriorate.
A duration of 0.5 or 1 ms is suggested for initial attempts.
Apply a repetitive test pulse (e.g. Seal Test) and press the Zap button while carefully
monitoring Membrane Current. Sometimes it helps to apply steady suction while
Zapping. Successful break-through is signaled by an increase in the current noise and
by large whole-cell capacitance transients.
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