Intracellular Recording In Vivo and Patch-Clamp Recording on Brain Slices - Animal Models of Acute Neurological Injuries: Injury and Mechanistic Assessments - page 114

2.4.2. Dialysis of
Intracellular Compartment
with Whole-Cell
Confi guration

Classic whole-cell recording causes a dialysis of intracellular
compartment, which may lead to time-dependent artifi cial changes
in electrophysiological responses during recording. Thus, perfo-
rated patch-clamp recordings may be helpful in some experiments.
Several specifi c perforating antibiotics, such as nystatin ( 18 ),
amphotericin B ( 19 ), and gramicidin ( 20 ), have been used to form
ion channels in cell membrane that are only permeable to monova-
lent ions, but not divalent cations (Mg 2+ , Ca 2+ ) and large molecules. In
addition, gramicidin-formed channels are not permeable to Cl − , and
therefore perseveres intracellular Cl − concentration.

The voltage clamp is based on the theory that the cell body is a
spherical shape so the command voltage dictates the membrane
voltage of the neuron and therefore the voltage-dependent channels
on the cell membrane will open or close according to the command
voltage through the electrode. However, in brain slices, most of
the dendrites of the neurons are preserved. The command voltage
can only control the membrane voltage of the cell body near the
electrode. The membrane voltage at the periphery of the cell body,
as well as the proximal dendrites, could not be fully controlled by
the command. Therefore, the amplitude and kinetics of the current
recorded from the neurons of brain slices might be distorted. We
should be aware of such space clamp problems when analyzing
data from neurons in brain slices. To avoid misinterpretation of the
results obtained from the brain slice preparation, it is important to
compare the data with those collected by other approaches, such as
acute dissociate neurons.

2.4.3. Space Clamp Issue

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