VCC 600  

Voltage-Current Clamp Model for Epithelial Tissues

Physiologic Instruments
 

 

The VCC 600 voltage-current clamp has been designed to be a flexible tool to aid the study of ion transport mechanisms by in vitro epithelial tissues. The VCC 600 provides the capability to control either the voltage or the current across the epithelium and is ideally suited for both electrophysiological studies as well as ion flux studies on epithelia. 


Features 

  PULSE GENERATOR- A built-in pulse generator which allows continuous
    monitoring of the tissue conductance

  DIGITAL 0.5" LED READOUT - of transepithelial voltage or current

  USER SELECTABLE CURRENT RANGES

  ELECTRODE OFFSET COMPENSATION

  FLUID RESISTANCE COMPENSATION - with user selectable ranges

  VOLTAGE OR CURRENT CLAMP - the ability to clamp either voltage or
    current across the epithelium

  DIGITAL 0.5" LED READOUT - of transepithelial voltage or current

  USER SELECTABLE CURRENT RANGES

  ELECTRODE OFFSET COMPENSATION

  FLUID RESISTANCE COMPENSATION - with user selectable ranges

  VOLTAGE OR CURRENT CLAMP - the ability to clamp either voltage or
    current across the epithelium

  BATH REFERENCE VOLTAGE - for use in    microelectrode and pH stat
    experiments

   OPTIONAL HIGH VOLTAGE OUTPUT
  RECORDER OUTPUTS - for continuous monitoring of transepithelial voltage
    and current

  EXTERNAL INPUT - allows an arbitrary waveform to be clamped

  COMPUTER INTERFACE JACK, RACK MOUNTABLE

 
Specifications
GENERAL CHARACTERISTICS

 ¤  INPUT RESISTANCE >109 Ohm differential
¤  COMMON MODE REJECTION >100 dB
¤  CLAMP OUTPUT ±13 V standard; ±35 V Option HV
¤  FREQUENCY RESPONSE 4 stage adjustment - internal pop switch
¤  DIGITAL DISPLAY 0.5" LED for easy readability
¤  TRANSEPITHELIAL VOLTAGE ±199.9 mV displayed, 10mV/mV recorder
    output
¤  GROUNDING Signal (circuit) ground is isolated from chassis and power
    grounds. Binding posts on the rear panel allow connection of circuit to
    chassis  ground.
¤  FLEXIBILITY: Jumper selectable current measurement and fluid resistance
    compensation ranges
DISPLAYED
CURRENT		 RECORDER
OUTPUT 		FLUID RESISTANCE
COMPENSATION
±1.999 nA 1 mV/nA 10, 20, 50, 100 kOhm
*optional 1, 2, 5, 10 MOhm
±1.999 µA 1 V/µA
±19.99 µA 1 V/µ A 1, 2, 5, 10 kOhm
±199.9 µA 10 mV/µA 100, 200, 500 ,1000 Ohm
±1999 µA 1 mV/µ A 10, 20, 50, 100 Ohm
±1.999 mA 1 V/mA

*for use with isolated perfused rental tubules.

VOLTAGE-CURRENT CLAMP

 OFFSET POTENTIAL COMPENSATION ±10 mV, ten-turn potentiometer and polarity switch.
FLUID RESISTANCE COMPENSATION push button adjustment with ten-turn potentiometer.For jumper selectable ranges at each current measurement setting. See TABLE.
DC CLAMP LEVEL
VOLTAGE-CLAMP: ±100 mV, x1 or x3 ten-turn potentiometer and polarity switch.
CURRENT CLAMP: range -150 % of maximum displayed current.

FUNCTION

ZERO: stand by mode, inputs V1 & V2 are internally grounded.
OPEN: open circuit, V1 & V2 are connected to sensing electrodes.
CLAMP: feedback loop is closed to control either current or voltage.

MODE

VOLTAGE/CURRENT CLAMP: selects either the transepithelial voltage or current to be clamped when FUNCTION is in the CLAMP position. (Note: Only CURRENT CLAMP mode is applicable to isolated, perfused rental tubules.)
LOCAL/REMOTE: selects control of the FUNCTION and VOLTAGE/CURRENT CLAMP switches to be from the front panel or from digital input to the REMOTE INTERFACE CONNECTOR. In REMOTE MODE the DC CLAMP LEVEL is disabled and an analog command signal is accepted from the computer.



PULSE GENERATOR

ON/OFF with ON indicator light
POLARITY selects +, - or bipolar pulses
SINGLE PULSE injects single pulse during normal period between pulses
RESET initializes interval timer

AMPLITUDE x1, 0-10 mV in 1 mV steps. x10, 0-10 mV in 10 mV steps
PULSE OUTPUT: x10 above values
PERIOD 0.1-99.9sec. Sets pulse interval. Thumbweel switch
DURATIN 0.01-9.99 sec. Sets duration of each pulse. Thumbwheel switch

 

 

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