Single Channel Epithelial Voltage/Current Clamp Systems

Single Channel Epithelial Voltage/Current Clamp Systems

The model VCC600 is a single channel device capable of controlling either the voltage or current across an epithelium. It is the most
versatile instrument in the VCC series. Basic features include compensation controls with calibrated 10-turn dials for electrode
offset voltage and fluid (series) resistance, user selectable ranges for current measurement gain, fluid resistance compensation and response frequency. A Clamp Level control allows a DC holding voltage or current to be set while a built-in pulse generator provides for applying unipolar or bipolar step changes in voltage or current from the holding level for tissue conductance/resistance measurements. Voltages and currents can be monitored via recorder outputs on the front panel and by a bright 3.5 digit LED digital panel meter. An interface connector for remote instrument control and data acquisition is provided on the rear panel. A high voltage option is also available to increase the output compliance voltage to ±35 V DC for certain types of experiments.

Item# Description U.S. List Price Quantity
69-0931 VCC600 Single Channel Voltage/Current Clamp System with High Voltage Option
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The model VCC600 is a single channel device capable of controlling either the voltage or current across an epithelium. It is the most
versatile instrument in the VCC series. Basic features include compensation controls with calibrated 10-turn dials for electrode
offset voltage and fluid (series) resistance, user selectable ranges for current measurement gain, fluid resistance compensation and response frequency. A Clamp Level control allows a DC holding voltage or current to be set while a built-in pulse generator provides for applying unipolar or bipolar step changes in voltage or current from the holding level for tissue conductance/resistance measurements. Voltages and currents can be monitored via recorder outputs on the front panel and by a bright 3.5 digit LED digital panel meter. An interface connector for remote instrument control and data acquisition is provided on the rear panel. A high voltage option is also available to increase the output compliance voltage to ±35 V DC for certain types of experiments.
In addition to the attributes it shares with the other instruments in the VCC line, the VCC600 has special features that have made it a popular instrument for electrophysiological studies of epithelia. These features include an active headstage that incorporates a virtual grounding amplifier for current measurement and an extra level of current gain to measure currents in the nanoampere (nA) range. This has permitted the instrument to be used for studies on tissues as small as isolated renal tubules and single isolated colonic crypts.
A switch and buffer amplifier in the headstage allow selection and continuous measurement of the potential on either side of the
epithelium. This output is available on the rear of the instrument can be used as a reference for microelectrode experiments so that the intracellular voltage can be measured directly across either apical or basolateral membranes regardless of side of impalement. Similarly, it can be used as the reference voltage in pH stat experiments, thereby eliminating a problem with some combination electrodes and pH meters in which a fraction of the transepithelial current may be shunted to ground.
The VCC600, as with all of the VCC series of voltage/current clamps, is compatible with the EasyMount diffusion (Ussing) chamber
systems and Harvard/NaviCyte diffusion (Ussing) chamber systems.
Specifications69-0931
Amplitude0 to 10 mV in 1 mV steps at X1 gain; 0 to 100 mV in 10 mV steps at X10 gain
Clamp FunctionFeedback loop is closed to control either current or voltage
Clamp Output
Common Mode Rejection? 100 dB
Current ClampCurrent gain dependent, 50% and 150% of max. displayed current
DC Clamp LevelSets DC holding voltage or current
Display3.5 digit, 1/2 in red LED
Duration0.01 to 9.99 sec duration of each pulse; set by 3-decade thumbwheel switch
Electrode InputsBanana jacks on headstage
External InputAllows arbitrary analog input signal to be clamped
Fluid ResistancePush-button current injection, compensation set by precision 10-turn dial, jumper selectable ranges
Frequence Response4-stage adjustment via internal switch
FunctionThree position rotary switch
GroundingSignal (circuit) ground is isolated from chassis and power grounds; binding posts on rear panel allow connection of circuit to chassis ground
HeadstageActive input stage for sensing voltage and current near preparation, cable length 6 ft
Input Resistance? 109 ?, differential, ? 1012 ? available as option
Local/Remote ModeSelects control to be from front panel switches or from remote interface
MeterSelects current or voltage to be displayed on panel meter
ModeTwo switches select operating modes
ModelVCC600HV
Offset Potential
On/Off‘On’ sends pulse output to clamp, red indicator light
Open FunctionOpen circuit, voltage inputs are connected to sensing electrodes
Period0.1 to 99.9 sec time period between pulses; set by 3-decade thumbwheel switch
PolaritySelects +, - or bipolar pulses to be generated
Power Requirements100/125 VAC, 60 Hz or 200/250 VAC, 50 Hz, user selectable
Pulse Generator0 to
Recorder Output CurrentJumper selectable, 1, 10, 100 or 1000 mV/
Recorder Output Voltage10 mV/mV, x10 transepithelial voltage
Reference BufferSwitch selectable to send V1 or V2 inputs to buffer amplifier in headstage; allows monitoring of bath potential on either side of epithelium; output via rear panel permits micro-electrode impalements or pH electrodes to be referenced to either V1 or V2
Remote Interface9 pin DB connector
ResetInitializes interval timer and injects pulse
Single PulseInjects single pulse during interval between pulses
SwitchesSubminiature toggle
Transepithelial Current
Transepithelial Voltage
Voltage Clamp
Voltage/Current (I/V) ModeSelects transepithelial voltage or current to be controlled when Function is on Clamp
Zero FunctionStandby mode, voltage inputs are internally grounded