Warner OC-725C, Руководство пользователя

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Now, advance the current electrode until its tip is slightly depressing the
plasma membrane of the cell and depress the Ve BUZZ pushbutton. Similar to
the voltage electrode BUZZ, the current electrode BUZZ produces a 1 V, 1 kHz
oscillation across the current electrode. This disrupts the cell membrane and
causes the tip of the electrode to impale the cell with no further movement
of the micro-manipulator. Once again, if the BUZZ technique fails to cause
penetration, further advance the current electrode until it “pops” through the
membrane.
Clamping the Cell
Activate the clamp by switching the CLAMP MODE switch to either the slow or
fast mode. NOTE: slow mode is useful for initial screening.
Adjust CLAMP GAIN control clockwise as far as possible without illuminating
the OVER VOLTAGE LED (located in the CURRENT ELECTRODE section).
NOTE: If the ALARM signal switch on the back panel is on, an alarm will sound
when the OVER VOLTAGE LED illuminates.
Clamping High Conductance Cells
DC GAIN mode (CLAMP section) may be required to clamp high conductance
(low resistance) cells. This condition will be evidenced by the inability of the
instrument to maintain a DC holding potential (to within 1% or better of the
set value) and the maximum instrument gain is not sufficient to provide a hard
clamp. DC GAIN mode provides an additional DC gain greater than 106 while
the AC gain remains at 2000 maximum for stability.
A Procedure for Recording from Oocytes
The clamped membrane potential can now be observed over time or it can
be manipulated by selecting the desired polarity and amplitude with the
controls located in the COMMANDS section. Alternatively, you can control
the COMMAND voltage externally from a computer by leaving the POLARITY
toggle switch in the off position and connecting the appropriate analog output
from your computer DAC to the COMMAND IN ÷10 BNC connector. (See Cable
Connections, page 20.)
Depending on the amplitude of the response you wish to record, you may
adjust the instrument GAIN to a higher or lower position. The CURRENT
ELECTRODE METER should now be displaying the current (in µA) that is
delivered to hold the cell at the designated command potential.
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