To perform recordings of fast events, such as the activation and inactivation of Na currents, it is essential to have accurate voltage control. The image shows currents and I/V characteristics of Nav1.5 expressed in HEK293 cells.

Cells were kindly provided by Millipore.

Cor.At^® cardiomyocytes are derived from mouse embryonic stem (ES) cells. Whole cell currents recorded in voltage clamp mode reveal cardiomyocyte-typical ion channels (K⁺, Ca²⁺ and Na⁺). Traces on the lower left show prolongation of the action potential upon application of Dofetilide (1 μM).

Cells were kindly provided by Axiogenesis. Download: Application Note

The left picture shows a typical action potential in hESC-derived cardiomyocytes (human embryonic stem cell-derived cardiomyocytes). The traces represent K⁺- (top left), Ca²⁺- (bottom left) and Na⁺-currents (top right). The lower right panel shows the corresponding I/V-relationships.

Cells were kindly provided by Geron/GE.

Alamethicin is a channel forming peptide and, when patch clamped, reveals multiple non-equidistant conductance levels due to formation of alamethicin oligomers in the bilayer. Alamethicin single channel conductances. Recordings from a GUV prepared bilayer in 85 mM KCl at -140 mV. Data were kindly provided by M. Sondermann/Prof. Behrends, Univ. Freiburg.

Traces were recorded in 100 mM KCl, 10 mM Hepes, 0.1 mM EDTA, pH 7 at -40 mV. Lipid: Diphtanoyl-PC.

Recordings were kindly supplied by ITC & CNR-Istituto di Biofisica, Trento, Italy.

Typical recording of the Irms noise level of a bilayer (DPhPC) on the Low Capacitance Holder. Typical values are 220 fA

(10 kHz filter frequency, 50 kHz sampling rate. Cf. 2.3 pA RMS on the standard Port-a-Patch^®).

Single channel recordings of BK channels as recorded from CHO cells in the cell attached mode at +60 mV (top), +40 mV (middle) and 0 mV (lowest trace).

Tobacco (Nicotiana tabacum L. cv Bright Yellow 2 [BY2]) cells are the most widely used plant cell culture. Depolarisation-activated outward currents in BY2 cell protoplasts. Shown are whole cell current in response to voltage steps (left) and the corresponding IV curve (right). From a holding potential of −40 mV, 500 ms voltage steps were applied from −60 mV to 60 mV in 20 mV increments, with 3 s intervals.

The image shows internal cAMP-activation of a transiently expressed plant CNG channel and subsequent external block by lanthanum. Activators and blockers were manually added to the intracellular and extracellular sides of the membrane.

Data were kindly provided by A. Kugler & P. Dietrich, Univ. Erlangen, Germany.

Representative current responses of an individual HEK-293 cell expressing Cav 2.2 to a standard voltage protocol. Average current-voltage relationship (n = 10). The error bars reflect the standard error of the mean (S.E.M.).
Cells were kindly provided by Millipore.

K_V1.3 currents (blue), endogenously expressed in Jurkat cells, were rapidly blocked by internal perfusion of Cs⁺ (light blue), and fully recovered after washout with K⁺ (grey). Internal solution replacement was repeated 19 times and the recording was stable for over 35 minutes, as shown in the lower graph.

Whole cell current responses of undifferentiated (left) and for 12 days differentiated (right) IMR32 cells to a voltage step protocol (holding −90 mV, stepping for 20 ms from −60 mV to +60 mV in 20 mV increments) are shown. The change in current shape indicating increased expression of K_V and Na_V are apparent.

Erythrocytes lack mitochondria and nuclei and consist mainly of hemoglobin. The membrane contains different ion channels, for example, a Ca²⁺-activated K⁺ channel and a volume-sensitive Na⁺/K⁺ pump. Here, single channel activity recorded from an erythrocyte in the cell attached configuration is shown.

Currents of RBL cells endogenously expressing K+ permeable channels (-100 mV) were measured. The external K+ concentration was changed using the Perfusion System and the standard, Laminar Flow Chamber. Time constant for solution exchange was approximately 100 ms. Low K+ (4.5 mM K+), high K+ (143 mM K+).

HCN2 whole cell current of stably transfected CHO cell before and after internal cAMP application. Subsequent block by external Cs⁺ was also performed on the same cell. Holding potential was –40 mV.

HCN2 clone was kindly provided by M. Biel, LMU, Germany.

Block of hEAG whole cell currents after the internal application of 200 µM TEA.

Data were kindly provided by Walter Stühmer, MPI for exp. Med., Göttingen.

Sticky compounds, such as some hERG blockers, exhibit expected IC₅₀ values with the Port-a-Patch^®. The concentrations of the half maximal block were: 1.27 nM (astemizole), 8.9 nM (cisapride), 163.7 nM (flunarizine) and 11.0 nM (terfenadine).

Cells were kindly provided by Cytomyx/Millipore, UK.

The image shows example traces for hERG mediated currents at 25 ± 2 °C (black) and 35 ± 2 °C (blue). The peak current amplitude was increased at 35 °C, and the rise time and decay time constants were faster at physiological temperature compared with those obtained at room temperature. Cells were kindly provided by Cytomyx/Millipore, UK.

Perforated and conventional whole cell configuration and derived Kv1.3-currents. Voltage-dependence was shifted significantly to more negative potentials in the whole cell configuration compared to the perforated whole cell configuration. Whole cell currents after a conventional membrane breakthrough (left) and perforated whole cell currents (right).

Whole cell recordings performed with the Port-a-Patch^®. Whole cell currents of HEK293 cells stably expressing hNav1.5 (left). Current-voltage relation of peak currents (right).

Cells were kindly provided by Cytomyx/Millipore, UK.

TRPV1 currents were elicited by the external application of 20 μM capsaicin. After capsaicin activation, the currents were partially blocked by the internal application of Ca²⁺-calmodulin (50 μM Ca²⁺ / 500 nM CaM). TRPV1 channels were expressed in CHO cells.

Currents mediated by BK channels expressed in CHO cells were studied using the Internal Perfusion System. Currents were elicited by a voltage step from -80 mV to +80 mV before and after adding an internal solution containing a higher concentration of free Ca²⁺.

Current response in RBL cells to a voltage ramp from –150 mV to +80 mV in the presence of a low and a high external K⁺ concentration (left). Voltage dependent block of the inward K⁺ current after the external additon of 50 µM Ba²⁺ (middle). Same block in response to a continuous voltage step to –150 mV (right) from 0 mV.  Low K⁺ (4.5 mM K⁺), high K⁺ (143 mM K⁺).

Recordings from HEK 293 cells expressing the electrogenic Na⁺/bicarbonate cotransporter (NBC1). Current responses to 200 ms voltage ramps in high external Na⁺ initially after establishment of the whole cell configuration (control), after application of HCO3- (bicarbonate), and after wash-out (wash-out). Data were kindly provided by Ira Kurtz, UCLA, USA.

K_V1.3 current was blocked by the internal application of increasing concentrations of quinidine (left) or TEA⁺ (right). For quinidine the IC₅₀ was determined as 15 μM (literature value external application 14 μM) and for TEA⁺ the IC₅₀ was determined as 0.9 ± 0.3 mM (n = 3) (literature value internal application 0.6 mM).

Typical chloride currents in four isolated lysosomes.Chloride currents were determined as difference currents between IV curves recorded in the absence and presence of extralysosomal high (64 mM) Cl^-. On the left a sketch is illustrating the methodology.

Data are taken from Schieder M. et al., The Journal of Biological Chemistry, 2010, 285(28), 21219-21222.

Voltage induced membrane movements of a Jurkat cell. (a) Deflection signal of the cantilever resting on the cell membrane at an indenting force of 1.0 nN. (b) Corresponding whole cell current. Upon depolarization of the membrane, the characteristic response of the voltage geate potassium channel K_V1.3 in Jurkat cells is observed. (c) Below the applied voltage protocol is displayed.

Date are taken from Pamir E., et al., Ultramicroscopy, 2008, 108, 552-557.

Mesophyll protoplasts are enzymatically isolated from tobacco leaves. Shown are whole cell recordings which demonstrate the hyperpolarization-activated inward currents in the protoplasts. A voltage ramp from −40 mV to −120 mV was applied.

Data were kindly provided by Berghöfer; Eing; Flickinger; Frey (Forschungszentrum Karlsruhe, Germany).

Mitochondria were isolated from rat cardiac tissue. The patch clamp measurements were performed in the cell attached configuration with an Axopatch 200B. Single channel currents were elicited by a voltage ramp from 0 mV to -80 mV. Due to the cell attached configuration inward currents are displayed as a positive current.

Shown are raw current traces from 1321 N1 cells expressing P2X3 receptors demonstrating the reproducability of the whole cell responses. Currents were activated by 100 ms application of 10 µM ATP. The waiting time between sweeps was 120 s (holding −60 mV).

Cells were kindly supplied by Evotec AG, Hamburg, Germany

A full dose response curve of quinidine acting on the hERG channel was obtained at physiological temperature (35 °C). The IC₅₀ for quinidine at physiological temperature was 1.3 ± 0.2 μM (n = 5), similar to that obtained at room temperature (1.0 ± 0.03 μM, n = 3).

Cells were kindly provided by Cytomyx/Millipore, UK.

The Laminar Flow Chamber can also be used for studying glycine receptors. The pharmacology of the hGlyRα1, expressed in a mouse fibroblast cell line (L-tk), was investigated. The EC₅₀ for glycine was determined as 89 ± 2.7 μM (n = 10) which is in accordance with the literature.
Cells were kindly provided by AstraZeneca, Sweden.

The Port-a-Patch^® and the Suction Control Pro was used to study the effect of pressure on functional MscL protein reconstituted in GUVs. Using symmetrical KCl solutions, MscL gating was observed at -30 mBar and -60 mBar (holding potential + 30 mV), shown as outward currents in the data traces.

Recordings from acutely isolated hippocampal granule cells show BK- and Ca_V currents. Whole cell currents were obtained by depolarizing voltage pulses from a holding potential of −80 mV.

Patch clamp recordings from cultured mouse primary neuronal stem cells were made in the whole cell configuration (holding potential −60 mV). Currents were evoked by 500 ms depolarizing voltage pulses, showing outwardly rectifying K⁺- currents.

Data courtesy of Dr. Gavin Dawe, National Uni­versity of Singapore.

Switching of internal solutions during gramicidin recordings from a lipid bilayer was obtained within seconds. A lipid bilayer was formed using giant unilamellar vesicles. Currents were recorded at a holding potential of +150 mV. The internal solution was switched from HCl to KCl, resulting in lower channel conductance.

Ligand dependent activation of GABA_A receptors can be recorded with the Laminar Flow Chamber with approx. 100 ms time constant for 10 μM GABA. Concentration dependent activation and desensitization of GABA_A (α1β2γ2) receptors was obtained by applying 1, 3 and 10 μM GABA for 2.5 s at a time interval of 20 s.

Here we show recordings from HEK293 cells transiently expressing a Shaker K mutant that has its inactivation removed (Shaker-IR). The holding potential was -80 mV. The current-voltage relationship of the tail currents reveals a half-activating potential of -27 mV.

Data were kindly provided by Dr. Kenton Swartz, NIH, Bethesda, USA.

Block of Shaker-IR by Agitoxin2. Shown are current recordings from HEK293 transiently expressing Shaker-IR. Currents were elicited by a 500 ms step to +50 mV from a holding potential of -80 mV. K⁺ gradients are the same as for the IV curve experiment shown above. 200 nM Agitoxin2 almost fully blocks the Shaker K⁺ current. Data were kindly provided by Dr. Kenton Swartz, NIH, Bethesda, USA.

Current response of a non-transfected Chinese hamster ovary (CHO) cell to a train of ultrasound pulses (US) in the absence (A) and presence (B) of contrast agent. The holding potential was -80 mV. Ultrasound signals had a centre frequency of 5 MHz. Pulses of 50 cycles were repeated for 2 s every 10 ms. Data were kindly provided by Dr. Cheri Deng, University of Michigan, USA.

Shown are mTRPM7 (in HEK293 cell) raw current responses to a voltage ramp voltage procotol  (−100 mV to 100 mV over 200 ms) recorded under control conditions and after subsequent internal perfusion with Mg²⁺ (left). Initally, currents showed some run-up before they became stable. The arrows in the timecourse on the right mark the timepoints for which the raw current traces are shown.

TRP channels recorded in HEK293 cells. Menthol (dark blue) activated the TRPM8 channels (shown on the left) and could be inhibited by genistein (blue). TRPV1 channels expressed in HEK293 cells (right) were stimulated by application of capsaicin.
TRPV1 data were kindly supplied by Dr. David Cohen, Oregon Health and Service University, Portland, OR, USA.

Whole cell current responses from HEK 293 cells transiently expressing TRPV1 to a ramp voltage protocol (‑100 mV to +100 mV). Capsaicin at a concentration of 2 μM reversibly activated the channel.

Data were kindly provided by David Cohen, Oregon Health & Science University, Portland, USA.

Raw traces of TRPV1 current responses to voltage ramps from –100 mV up to +100 mV. TRPV1 current at RT (28°C), during two stimulations by application of heated solution (34°C and 36°C), and after cooling down to RT (29°C). The picture on the right-hand side shows the current amplitudes as recorded at -100 mV and +100 mV plotted against time.

The image shows a representative current trace recorded from a planar lipid bilayer in which purified KcsA channels were reconstituted (100 mM KCl, asymmetric pH; pH 4/pH 7). A ramp from -100 mV to +100 mV was used to evoke the single channel events.

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Channels were activated in the presence of spermine (0.5 mM). The downward spikes represent the closure events due to the effect of spermine.

Data were kindly supplied by Prof. Mathias Winterhalter, Jacobs University, Bremen, Germany.

Reconstituted Alpha hemolysin channels are constantly open at positive and negative membrane potentials. Gating is observed as a result of the passage of a single stranded DNA molecule through the pore. Recordings were performed on the Port-a-Patch^®.

Data were kindly supplied by Prof. Fritz Simmel, Technical University of Munich, Munich, Germany.

Representative traces of the IP₃ (inositol-triphosphate) receptor were recorded at different voltages in the presence of IP₃ (0.2 mM free Ca²⁺ and 1 mM Na₂ATP, 140 mM KCl). Addition of 2 μM IP₃ on the cytosolic side evoked openings of the IP₃ receptor.

Data were kindly supplied by Prof. Colin Taylor, University of Cambridge, Cambridge, UK.

Shown are single channel events of TRPM8 reconstituted in a planar lipid bilayer. The recordings were made with the with the Port-a-Patch^®. The channel was activated by PIP2 and methanol. Currents were recorded at 100 mV.

Data kindly provided by Dr. Zakharian and Dr. Rohac From UMDNJ New Jersey Medical School, Newark, NJ 07103, USA