This document provides an overview of the perforated patch-clamp technique, including: - The rationale for using perforated patch-clamp is to overcome the dialysis of intracellular components that occurs with traditional whole-cell recording. - Common perforants like nystatin and amphotericin B form small pores that allow electrical access while preventing diffusion of larger molecules. - Gramicidin is also used and has the advantage of preserving intracellular chloride concentration. - Step-by-step guidance is given for performing recordings with nystatin, amphotericin B, and gramicidin. Progress of perforation is monitored by observing changing current responses to voltage pulses.

1. 71
Yasunobu Okada (ed.), Patch Clamp Techniques: From Beginning to Advanced Protocols,
Springer Protocols Handbooks, DOI 10.1007/978-4-431-53993-3_4, © Springer 2012
Chapter 4
Perforated Whole-Cell Patch-Clamp Technique:
A User’s Guide
Hitoshi Ishibashi, Andrew J. Moorhouse, and Junichi Nabekura
Abstract
The patch-clamp technique has revolutionized the study of membrane physiology, enabling unprecedented
resolution in recording cellular electrical responses and underlying mechanisms. The perforated-patch vari-
ant of whole-cell patch-clamp recording was developed to overcome the dialysis of cytoplasmic constitu-
ents that occurs with traditional whole-cell recording. With perforated-patch recordings, perforants, such
as the antibiotics nystatin and gramicidin, are included in the pipette solution and form small pores in the
membrane attached to the patch pipette. These pores allow certain monovalent ions to permeate, enabling
electrical access to the cell interior, but prevent the dialysis of larger molecules and other ions. In this
review we give a brief overview of the key features of some of the perforants, present some practical
approaches to the use of the perforated patch-clamp mode of whole-cell (PPWC) recordings, and give
some typical examples of neuronal responses obtained with the PPWC recording that highlight its utility
as compared to the traditional whole-cell patch recording configuration.
The patch-clamp recording technique represents a significant
advance for cellular physiology and neuroscience in that it has
enabled direct measurement of the activity of individual ion
channels that provide the molecular basis of cellular excitability (1).
The utility of the technique is illustrated by the further various
configurations that can be achieved to record electrical activity in
excised patches or for the whole cell (2). One of the features of this
“whole-cell” recording technique is that the relatively vast solution
inside the recording electrode (~10 ml) can completely replace the
much smaller volume of intracellular solution (~10 pl). Such
control over the internal ionic concentration can be advantageous
for certain experiments, such as isolating particular ionic currents,
4.1. Introduction:
Rationale for the
Perforated
Whole-Cell
Patch-Clamp
Technique

2. 72 H. Ishibashi et al.
loading specific compounds into cells, or careful quantification of
ion channel selectivity profiles. However, this intracellular dialysis
is a double-edged sword: Soluble components that influence
cellular excitability and contribute to signaling pathways are dialyzed
from the cell. One frequently encountered consequence is that
receptor-mediated responses and/or ionic currents that require
soluble second messengers are absent or rapidly “run down” during
conventional whole-cell recordings (3, 4). Furthermore, intracel-
lular ion concentrations are disrupted, hampering efforts to deter-
mine physiologically relevant responses or properties of channels
and receptors (5, 6).
The problems of cell dialysis have been effectively overcome
with the perforated patch-clamp whole-cell (PPWC) technique.
With this approach, a membrane-perforating agent is used to
provide access to the cell interior without mechanical rupture of
the membrane attached to the patch pipette. The idea was initiated
by Lindau and Fernandez (3), who used ATP (~0.5 mM) to
permeabilize the patch membrane and record the passive electrical
properties of mast cells during antigen-induced degranulation, a
response that was absent in cells dialyzed during conventional
whole-cell recordings. The access resistances (0.1–5.0 GW) were
very high, however, and the use of ATP as a perforant is limited to
membranes containing ionotropic P2X receptors. An improvement
was the use of the antibiotic nystatin, which provided lower
(18–50 MW) and stable access resistance (4). Much wider applica-
bility of the technique has resulted from use of this and other
perforants (described below) that can spontaneously form channels
in numerous membranes and result in access resistances that under
the most optimal conditions may approach values comparable to
those obtained with conventional whole-cell recordings.
Table 4.1 compares a number of commonly used perforants (see
also Fig. 4.1a). Nystatin (4) and amphotericin B (11) are structur-
ally similar antibiotics derived from streptomycetes (Streptomyces)
bacteria. They contain a large, amphiphatic polyhydrophylic lactone
ring that allows them to form aqueous pores in the cell membrane.
The properties of these polyene antibiotics have been well charac-
terized in lipid bilayers. Their effect on membrane conductance
(reflecting their stability as membrane pores) is highly dependent
on the antibiotic concentration, membrane composition, and
temperature (7, 22). For example, sterols in the membrane enhance
membrane conductance, and increasing temperature reduces it.
The ion permeation properties of the two agents are similar
(Table 4.1), both being modestly selective for monovalent cations
4.2. Comparison
of Perforants
Commonly
Employed

3. 734 Perforated Patch Clamp
Table 4.1
Characteristics of perforants used in perforated patch-clamp recordings
Perforant Nystatin Amphotericin B Gramicidin b-Escin
Class Polyene antibiotic,
Streptomyces
nousei
Polyene antibiotic,
Streptomyces
nodosus
Linear polypeptide antibi-
otic, Bacillus brevisa
Saponin
derivative
Pore structure Lactone ring,
interacts with
sterols to forms a
barrel-like pore
Lactone ring,
interacts with
sterols to forms a
barrel-like pore
15 Alternating dl-amino
acids in b-sheet as
end-on-end dimer
?
Pore radius ~0.4–0.5 nmb
~0.4–0.5 nmb
£0.35 nmc
>10 kDa
Selectivity Weakly cationicd
(PK
:PCl
= 30:1)
(PK
:PCl
= 40:1)
Weakly cationicd
(PK
:PCl
= 30:1)
K+
³ Na+
³ Li+
Highly cationic,d
PCl
~0
Cs+
³ K+
³ Na+
³ Li+
> Tris+
Nonselective,d
Ca2+
permeable
Conductance ~5 pSe
~6 pSe
~50 pSf
H+
> Cs+
> K+
> Na+
> Li+
?
Stock conc.g
Methanol
(5–10 mg/ml)
DMSO (25–
50 mg/ml)
DMSO (25–
100 mg/ml)
Methanol (10 mg/ml)
DMSO (2–50 mg/ml)
H2
O
(25–50 mM)
Final conc.g
20–400 mg/ml 25–250 mg/ml 5–100 mg/ml 25–50 mM
Key refs. (4, 7–10) (7, 10–12) (5, 12, 13) (14, 15)
a
Gramicidin used in most laboratories is commonly gramicidin D, a combination of gramicidin A, B, and C.
b
Inferred from lipid bilayer experiments with nystatin or amphotericin applied to both sides of the lipid
bilayers (and different from the channel from one-sided application as used for PPWC recordings).
c
Myers and Haydon (16) reported that tetramethylammonium (diameter 0.7 nm) was impermeant.
d
The selectivity of the polyene antibiotics has not been quantified, although a value of 10:1 appears in the
literature. The values cited here are calculated using the Goldman–Hodgkin–Katz equation and the
~50 mV potential across nystatin-doped bilayers in a tenfold KCl activity gradient (17, 18), and from the
15- to 16-mV shift in Vrev
shown in Fig. 4.3 of (4) in a twofold KCl gradient, with concentrations con-
verted to activities. b-Escin is likely nonselective. Permeability sequences are from (17) for amphotericin B
and from (16, 19) for gramicidin.
e
Conductance values from lipid bilayers in symmetrical 2 M KCl (nystatin (17); amphotericin (20)). Lower
(<1 pS) values would be predicted in physiological ionic strength (20).
f
Conductance values are from lipid bilayers in symmetrical 2 M KCl (21). In approximate physiological
ionic strengths (0.1 M), conductances were about 10 pS (KCl) and 5 pS (NaCl).
g
A range of values are given in the literature (including those cited under key references) and are based on
personal experience. For nystatin and gramicidin, DMSO and methanol can be interchanged. Little infor-
mation is published about concentration dependence. Tajima et al. (19) noted less frequent perforation
(and higher Ra
) as gramicidin was lowered from 100 mg/ml, although Kyrizos and Reichling (13)
reported more frequent spontaneous membrane rupture at >20 mg/ml.

4. 74 H. Ishibashi et al.
and impermeant to divalent ions (17); they also have low single
channel conductance and a pore diameter small enough to exclude
molecules larger than glucose (~0.8 nm) or sucrose (~1 nm).
Remarkably, the permeation properties of the amphotericin B and
nystatin pores change to predominantly anion-selective when
added to both sides of the membrane (18). Fortunately, however,
their lateral diffusion is limited by the seal (23), and access from
the interior membrane side does not occur in PPWC recordings
(unless the membrane ruptures).
The modest ion selectivity of these antibiotics results in
eventual equilibration of all intracellular monovalent ions with the
pipette concentrations. In contrast, the use of the highly cation-
selective linear polypeptide antibiotic gramicidin as the perforant
results in preservation of the physiological intracellular Cl−
concen-
tration (5, 12). Gramicidin has negligible permeability to multivalent
Fig. 4.1. Overview of cell perforation. (a) Relative size and selectivity of commonly used
perforants. (b) Current responses to a −5 mV voltage pulse (DV) during the stages of sealing
a patch pipette to a cell to form a GW seal (upper drawing ) followed by subsequent
perforation of the patch membrane and cancelation of the current transients (lower traces ).
The recordings were obtained using an acutely isolated hippocampal neuron.

5. 754 Perforated Patch Clamp
ions and monovalent anions under physiological conditions in both
bilayers and cells (Table 4.1) (16, 19). Although it has a minimal
pore diameter similar to those of amphotericin B and nystatin, it
has much larger single-channel conductance. Gramicidin PPWC
recordings have resulted in a greater understanding of Cl−
homeo-
stasis in cells under various conditions and of the physiological
responses of Cl−
permeant ionotropic g-aminobutyric acid (GABA)
and glycine receptors (5, 12, 24). Intracellular Cl−
may also modify
aspects of cell signaling or ion channel gating (25, 26). Although
amphotericin B has been reported to produce slightly better and
faster perforation than either nystatin or gramicidin (11, 13), all
three perforants can produce access resistances ~10–20 MW or
lower under optimal conditions. Factors beyond the perforant may
be more important for low access recordings, such as appropriate
tip-filling times, a steeply tapering pipette shank with low resistance,
and a freshly made perforant–pipette solution (11).
The need to solubilize the above ionophores in nonaqueous
solvents and dissolve them in pipette solution led to an evaluation
of alternate simpler (and less expensive) perforants such as the
saponin derivative b-escin. b-Escin can produce greater and more
frequent perforation than either amphotericin B or nystatin (14, 15),
it is more stable in aqueous solution, and it is less costly. However,
b-escin pores are significantly larger, with divalent ions and even
high-molecular-weight compounds (up to 10–15 kDa) permeating;
hence, it is not suitable when native concentrations or small signal-
ing molecules need to be maintained. The larger pore size has been
utilized to fill cells with fluorophores such as fluo-2 (14).
The following is a step-by-step description of our typical method
for using amphotericin B or nystatin followed by that for
gramicidin.
1. A stock solution of amphotericin B or nystatin is prepared at a
concentration of 50–100 mg/ml in dimethylsulfoxide (DMSO)
on the day of the recording. This stock solution is kept away
from light and at room temperature.
2. The stock solution (2 ml) is added to 1 ml of internal pipette
solution and mixed using ultrasonication, yielding a final
concentration of 100–200 mg/ml. The DMSO concentration is
0.2% (vol/vol). We avoid filtering these solutions, although Rae
et al. (11) reported that amphotericin B may be filtered through
0.2-mm filters without loss of activity. Fresh nystatin or amphot-
ericin should be added to the pipette solution every 2–3 h.
4.3. Practical
Guide to
Perforated Patch-
Clamp Recordings
4.3.1. Amphotericin B
or Nystatin

6. 76 H. Ishibashi et al.
3. Both polyene antibiotics and gramicidin at the tip of the patch
pipette may impair the initial GW seal formation; consequently,
prefilling the tip of the pipette by brief immersion into an anti-
biotic-free solution may be necessary. The optimal time for
pipette tip immersion depends on multiple factors, including
pipette shape and diameter [larger tips require less filling time,
smaller-tip pipettes (~ > 5 MW) may not need filling], the per-
forant concentration used (a lower concentration requires little
or no filling), and the time required between filling and sealing
(with slower procedures requiring more tip filling). The time
can be determined empirically, aided by microscopic inspec-
tion of tip geometries and filling heights. In our experience
with filament-free borosilicate glass capillaries of 3–7 MW and
with short and blunt tapers, filling for about 2 s is optimal. The
remainder of the pipette is back-filled with the internal pipette
solution containing the perforant. Small air bubbles at the tip
are rapidly and easily removed by tapping the pipette shaft with
the index finger.
4. The patch pipette is secured in the pipette holder and dipped
into the external solution in the recording chamber and guided
toward the cell as rapidly as possible, before the antibiotic
diffuses to the tip. No positive pressure is applied during the
approach. After gently pushing the pipette tip onto the cell
membrane, causing a slight increase of the pipette resistance,
gentle negative pressure/suction is applied to obtain the GW
seal (Fig. 4.1b). Canceling the fast capacitive transients helps
with subsequent monitoring of perforation.
5. The pipette potential is subsequently typically held between
−40 and −70 mV, gradually approaching the cell’s resting
membrane potential as perforation proceeds. The progress of
perforation is monitored by visualizing at high temporal reso-
lution the current response to repetitive hyperpolarizing
voltage pulses of about 5–10 mV (DV) (Fig. 4.1b). As the access
resistance (Ra
) decreases and electrical contact with the cell
improves, a current transient due to the cell membrane capaci-
tance (Cm
) is observed. The amplitude of this current transient
is given by DV/Ra
(hence, the current response increases as
perforation proceeds), and the decay time constant is given by
Cm
× Ra
(hence, the current decay gets sharper/faster as perfo-
ration proceeds). The values of Cm
and Ra
can be quantified by
analyzing the current transient or read from the capacitance
and series resistance cancelation dials off the patch-clamp
amplifier. Recordings can commence once the Ra
has stabilized
at a suitable value and then is compensated for. We routinely
obtain stable Ra
< 30 MW by 30 min. Ra
should be monitored
and adjusted during the experiment, and data should be used
only during periods when this value is relatively stable.

7. 774 Perforated Patch Clamp
The general procedure for the gramicidin-perforated patch is the
same as for amphotericin or nystatin, with some additional points
as follows. The stock solution is prepared by dissolving gramicidin
D in DMSO at a concentration of 2–50 mg/ml and may be stored
for 1–2 days at −20°C. The patch pipette solution contains grami-
cidin at 5–100 mg/ml, with the most appropriate concentration
determined in preliminary experiments. Higher concentrations
accelerate perforation speed but may result in spontaneous rupturing
of the patch membrane (this seems to depend on the preparation)
and requires prefilling of the pipette tip with gramicidin-free solu-
tion. A fresh pipette-filling solution needs to be prepared every
1–2 h to obtain low-access resistance recordings.
The lipophilic nature of the polyene antibiotics and gramicidin
results in difficulties in using them in physiological solutions,
including time-consuming preparation, large solvent concentrations,
rapid loss of potency in pipette solutions, and interference with GW
seal formation. Some of these problems can be overcome by using
b-escin, but this large pore is not suitable for many applications.
Horn and Marty (4) perfused the pipette with nystatin after form-
ing the GW seal, but it requires a pipette perfusion system.
An alternative method (27, 28) used the bipolar moleculues
fluorescein or N-methyl-d-glucamine (NMDG) to help disperse
and solubilize nystatin or amphotericin B. A stock solution is made
from 5 mg nystatin and 20 mg fluorescein in 1 ml methanol, or from
a 0.1 M solution of NMDG dissolved in methanol (pH adjusted to
about 7 with methanesulfonic acid in the presence of 0.01 M phenol
red) to which nystatin (5 mg/ml) was added. Immediately before
use, 50 ml of the stock solution is placed in a polyethylene test tube
and dried completely with a stream of N2
gas. Pipette solution (1 ml)
is added to the tube and briefly vortexed. The pipette solution can
be filtered through a 0.22-mm syringe filter; tip filling is not required
(hence perforation is achieved more rapidly). Positive pressure can
be applied during the approach to the cell, which makes this particu-
larly useful for blind patch-clamping in tissues slices. As with other
perforants, flouroscein is light sensitive. In fact, whole-cell access can
be reversibly closed by the microscope light (27).
The activity of some ion channels requires cytoplasmic constituents
that are lost with the formation of cell-free patches, such as out-
side-out patch configuration. Withdrawal of the pipette following
formation of the PPWC configuration can result in formation of a
perforated excised vesicle, analogous to an outside-out excised
membrane patch but in which larger intracellular molecules and
hence signaling pathways are maintained (8). The perforated vesicle
allows recording of single channels without marked run-down.
It also allows investigation of local signal transduction pathways
that modulate single-channel activity.
4.3.2. Gramicidin
Perforated Patch
4.3.3. Some
Alternatives
4.3.4. Perforated
Vesicles Preparation

8. 78 H. Ishibashi et al.
We illustrate here some of the benefits of PPWC recordings with a
few brief examples of responses from acutely isolated and primary
cultured neurons.
Dialysis of cytoplasm and/or the presence of exogenous Ca2+
che-
lators (e.g., EGTA) results in a gradual loss of Ca2+
from internal
stores, particularly when these stores are evoked to release Ca2+
.
This is illustrated in Fig. 4.2, which shows both conventional and
PPWC recordings of K+
currents in response to repetitive bath
application of caffeine, which releases Ca2+
from intracellular stores
and activates Ca2+
-activated K+
channels on the cytoplasmic mem-
brane (29). The response to caffeine gradually decreases in ampli-
tude on conventional whole-cell recordings but is constant for
about ³1 h on the amphotericin B PPWC recordings.
A peculiar property of high-voltage-activated Ca2+
currents is that
they show a time-dependent decrease in amplitude during conven-
tional whole-cell recordings, a process termed “run-down.” Various
4.4. Examples
of the Utility of
Perforated Patch-
Clamp Recordings
4.4.1. Intracellular Ca2+
Homeostasis
4.4.2. Run-Down of
Voltage-Activated Ca2+
Currents
Fig. 4.2. Perforated patch-clamp whole-cell (PPWC) mode maintains Ca2+
stores. Current
responses to 10 mM caffeine in acutely isolated rat CA1 hippocampal neurons recorded
under conventional whole-cell recordings (a) or amphotericin B PPWC recordings (b) Note
that the response amplitude runs down in (a) but is constant in (b). Caffeine was applied
each ~5 min. Recordings were performed at a holding potential (VH
) of −50 mV.

9. 794 Perforated Patch Clamp
attempts have been made to prevent run-down, including application
of substances to maintain channel phosphorylation and/or protect
against proteolysis, but none of these efforts has been satisfactory.
In contrast, run-down of voltage-activated Ca2+
channels is mark-
edly reduced/delayed using nystatin PPWC recordings (Fig. 4.3).
The stable recording of Ca2+
channel currents has allowed, for
example, detailed pharmacological dissection of the contribution
of different voltage-activated Ca2+
channels in different prepara-
tions (30, 31).
On conventional whole-cell recordings and PPWC recordings
using the polyene antibiotics or b-escin, the intracellular Cl−
con-
centration ([Cl−
]) equilibrates with that in the pipette [Cl−
]. In
contrast, gramicidin PPWC preserves the “normal” intracellular
[Cl−
] and enables one to record the physiological response of
Cl−
-permeant channels; it also allows us to investigate the modulation
of intracellular Cl−
homeostasis. Figure 4.4a compares the response
of ionotropic hippocampal GABA receptors when recorded using
a conventional whole-cell or gramicidin PPWC technique at the
same holding potential (VH
) of −50 mV. The direction of the cur-
rent response is completely different, reflecting the different intra-
cellular [Cl−
] and hence driving force. The physiological range of
intracellular [Cl−
] (~5–30 mM) is less than often used in pipette
solutions in conventional whole-cell recordings (~150 mM). The
gramicidin PPWC technique can be used to measure the intracel-
lular [Cl−
] as shown in Fig. 4.4b. Currents through the anion-
selective ionotropic GABA or glycine receptors are measured at
different holding potentials, and a current–voltage curve can be
4.4.3. GABA and
Glycine Responses
Recorded by the
Gramicidin-Perforated
Patch Recording
Fig. 4.3. Nystatin PPWC mode prevents the run-down of Ca2+
channel currents. Typical traces of high-voltage activated Ca2+
currents recorded from acutely isolated rat intracardiac ganglion cells using conventional (left panel) or PPWC (right panel)
recordings. Current traces obtained at the beginning of the experiment (control) and 30 min later (30 min) are superimposed.

10. Fig. 4.4. Physiological g-aminobutyric acid (GABA) and glycine responses and intracellular
[Cl−
] measurements using the gramicidin PPWC technique. (a) GABA-induced outward
and inward currents recorded at a VH
of −50 mV before (left trace) and after (right trace)
rupture of the membrane during a gramicidin PPWC recording. Membrane rupture results
in a much higher intracellular [Cl−
] as the cell equilibrates with the pipette [Cl−
] (~150 mM).
Hence, the GABA response changes from an outward current (representing Cl−
efflux) to
an inward current (Cl−
influx). (b) Glycine-induced currents recorded using the gramicidin
PPWC recording at various VH
s values in cultured spinal cord neurons are measured to
construct a corresponding current–voltage curve from which the Vrev
(arrow) is deter-
mined. The intracellular [Cl−
] is estimated from a derivation of the Nernst equation:
[Cl−
]in
= [Cl−
]out
exp(Vrev
F/RT), where F is Faraday’s constant (96,485 Cmol−1
), R is the gas
constant (8.3145 VCmol−1
K−1
), and T is absolute temperature (293.15 K at 20°C). (c) Such
measurements are used to demonstrate that furosemide causes a reversible increase in
the intracellular [Cl−
]. This is due to direct inhibition of K+
-coupled Cl−
efflux via the neu-
ronal KCC2 transporter. The graph plots the mean ± SEM from five experiments.

11. 814 Perforated Patch Clamp
plotted. If using ramp voltage responses, control currents in the
absence of GABA or glycine should be subtracted from those in
the presence of GABA or glycine. The X axis intercept of this curve
(the reversal potential, Vrev
) gives the equilibrium potential where
the driving force due to the membrane voltage cancels out that
from the concentration gradient. This is expressed mathematically
by the Nernst equation, from which the intracellular [Cl−
] can be
estimated (Fig. 4.4b). Precise quantification of Vrev
and intracellu-
lar [Cl−
] requires consideration of all permeant ion species, activity
coefficients, and liquid junction potentials (32); the latter can be
up to ~10 mV or more if using larger ions in the pipette solution.
These recordings should use a K+
-based solution in the pipette, as
the intracellular [Cl−
] is sensitive to transmembrane K+
(and, to a
lesser extent, Na+
) gradients, and some other cations (e.g., Cs+
) can
significantly inhibit some of the key Cl−
transporters (33).
Figure 4.4c shows the effect of furosemide, a Cl−
transporter inhib-
itor, on the intracellular [Cl−
] in isolated hippocampal neurons.
The ability to measure the intracellular [Cl−
] by the gramicidin
PPWC technique has facilitated revealing developmental- and
injury-induced changes in intracellular Cl−
homeostasis (34, 35).
This chapter has highlighted some of the benefits of the PPWC
technique, but there are also some drawbacks potential users need
to consider. First, PPWC recordings are much more time-consuming
than conventional whole-cell recordings: fresh perforant-containing
pipette solutions are required, and there is a wait (often ³30 min)
for perforation and stabilization to occur. Second, only under the
most optimal conditions can access/series resistances similar to
those under conventional whole-cell recordings be obtained.
Usually they are much higher and one must (as with conventional
whole-cell recordings) be aware of the voltage errors and filtering
effects of this access resistance. A voltage offset (=pipette current ×
Ra
) must be subtracted from VH
, and the −3 dB of the filtering
effect = 1/[2p × Ra
× Cm
]. Series resistance compensation can reduce
these errors. Finally, one must also be aware of a Donnan potential
between the VH
and the real membrane potential that arises as the
large anions in the cell cannot equilibrate with the patch pipette
solution. As discussed by Horn and Marty (4), this may be as high
as ~10 mV with a KCl pipette solution. This potential can be
reduced by including large impermeant ions in the pipette, but it is
difficult to measure or estimate it precisely. Hence in PPWC recordings,
one must be aware of potential inaccuracies in citing absolute
voltages associated with current responses (e.g., Kd
for activation
or inactivation).
4.5. Drawbacks
of the Perforated
Patch-Clamp
Technique

12. 82 H. Ishibashi et al.
The patch-clamp technique has revolutionized the study of
membrane proteins and their contribution to physiology, pharma-
cology, and neuroscience. This chapter briefly reviewed the proce-
dures and applications of the various configurations of the
perforated patch-clamp configuration. It is hoped the information
included will enable electrophysiologists to make more informed
decisions about adding the perforated patch-clamp technique to
their repertoire of means to study cellular excitability.
References
4.6. Conclusion
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