Guide to Electrophysiological Recording • 43
Chapter 4
400 pA
3 ms
1 MIN
2 MIN
3 MIN
4 MIN
5 MIN
Figure 3.3. Going whole-cell: capacity transients observed during amphotericin partitioning.
Low Noise Techniques
The MultiClamp 700A is capable of producing stable, low-noise recordings. To
realize this performance the user must pay close attention to other sources of
noise. This is because the total rms noise of a patch clamp recording is the square root
of the sum of the individual squared rms noise sources. This means that any particular
noise source that is large will dominate the total noise and make other noise sources
insignificant. Therefore, all potentially contributing noise sources must be minimized.
Specifically, the headstage, the pipette glass, the holder, and the seal contribute
significantly even under circumstances where extraneous noise pickup from the
environment is negligible. It is absolutely crucial that the entire preparation be
properly shielded, and that hum from power supply, mains, and other sources be
negligible, i.e., <
0.1 pA
p-p
. (Actually, < 0.01 pA
p-p
is possible with some effort.) In
To Next Page
Loading...
Need help?
General
