Warner OC-725C, Руководство пользователя

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Publication 5720-001 REV1.0
Introduction
The model OC-725C Oocyte clamp is designed for two-electrode, whole-cell voltage
clamping of Xenopus oocytes, as well as for other large cells and cell structures such as
squid axons. The instrument has several features making it ideal for these purposes.
Unique Features
High Voltage Compliance: The OC-725C combines high AC and DC gains and a voltage
compliance of ±180 V to insure fast, nonsaturating clamp performance under nearly any
condition. The AC clamp gain is variable up to 2000. An additional DC gain of 106 may be
employed for high conductance cells or leaky oocytes.
Two clamp speeds are available. The Slow mode is used for screening oocytes or for
applications not requiring rapid response times. The Fast mode is used for accurate
voltage clamping of fast whole cell currents. Response time in the Fast mode is 350 µs
(10-90% rise time) when applying a 100 mV step to a model cell.
Bath Clamp Headstage: The current measuring range of the OC-725C bath clamp
headstage is extended at both ends by a 3-position range multiplier. This allows smaller
currents to be amplified to usable levels while larger currents (up to 1 mA) can be
recorded without saturation.
The unique design of the bath clamp eliminates the need for series resistance
compensation. It provides an accurate measurement of bath current by creating a virtual
ground in the bath while simultaneously clamping the bath potential at zero.
Dual Oocyte Studies: Studies involving two oocytes in a common bath requires two
clamp amplifiers. The bath clamp headstage cannot provide effective clamping because
it cannot separate the individual currents from the combined current appearing in
the bath. The OC-725C solves this problem by the application of an internal switch
permitting measurement of the current in series with the current electrode instead of
in the bath. Additionally, an optional differential voltage headstage is available which
subtracts the voltage drop across the series resistance in the bath.
Voltage Headstage Probe: The voltage measuring headstage is a single-ended,
high-impedance probe. Its small size, convenient mounting rod, and two meter cable
make for easy attachment to a micropositioner. A supplied electrode holder with a 2 mm
jack mounts directly on the headstage.
Voltage and Current Meters: Independent meters provide simultaneous displays of
membrane voltage Vm and membrane current Im . To assure proper impalement of the
current electrode, the current meter displays membrane potential, V
e
, from the current
electrode before the clamp circuit is activated.