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Cut-oocyte voltage-clamp: help needed;

Quoc Thang NGUYEN qnguyen at parker.bio.uci.edu
Wed Nov 8 13:38:49 EST 1995

	Dear Netters,

	Is there anyone using a cut-oocyte voltage-clamp (developed by E. Stefani)?
This device is supposed to clamp a small patch of an oocyte in "no time" (<<1ms).
I am having trouble using a home-made design. Although everything seems to be
working fine with a model cell (the clamp can follow a 100mV voltage-jump with a
capacitive transient that settles within a few nA in 500us, with a filter setting
at 2-5kHz; the capacitance of the membrane is 50nF), I am having trouble using it
on the real thing. I have two main problems (not mentioning several minor ones!):

1) Size of the capacitance transient: I cannot go below 2ms with a 100mV pulse;
I reduced the resistance of the bridges as much as possible (~1.5kOhms), used
a vaseline rim, etc..., to no avail.
2) Stability of the preparation: the membrane resistance loses its value rapidly
within a few minutes. I use the saponin permeabilization method.

	I would be very grateful if you can share your experience in using a
cut-oocyte voltage clamp on this newsgroup. Thank you in advance.

Quoc Thang NGUYEN
Laboratory of Cellular and
Molecular Neurobiology
Dept. of Psychobiology
University of California, Irvine
Irvine, CA92717 USA
Ph: (714) 824-4730
Fx: (714) 824-3522

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