BC-535 Preliminary, Rev. 060126
29
where i is the current appearing at the I
m
output, k is a constant of proportionality, and A is the area
of the forming membrane. It should be apparent from the preceding discussion that the magnitude of
the current, and hence the amplitude of the resulting square wave, is linearly proportional to the area
of the bilayer membrane.
Since the amplifier output is scaled to 1 mV/pF when the
BC-535
is in
CAP TEST
mode, application
of the preceding discussion to the amplifier indicates that the measured capacitance of a membrane is
simply the amplitude of the square wave (expressed in mV) divided by the instrument gain. For
example, a 100 pF membrane would yield a 1000 mV square wave (p-p) when the amplifier gain is set
to 10 mV/pA.
Suggested References
1.
Ion Channel Reconstitution edited by C. Miller, Plenum Press, New York (1986). In particular,
chapter 5, "How to set up a bilayer system" covers many important aspects on the subject.
2.
Single-Channel Recording edited by B. Sackman and E. Neher, Plenum Press, New York (1985).
3.
Reconstituting channels into planar membranes: a conceptual framework and methods for fusing
vesicles to planar bilayer phospholipid membranes. F.S. Cohen and W.D. Niles, Methods in
Enzymology, 220:50-68 (1993)
4.
Planar bilayer recording of ryanodine receptors of sarcoplasmic reticulum. R. Coronado, S.
Kawano, C.J. Lee, C. Valdivia, and H.H. Valdivia, Methods in Enzymology, 207:699-707 (1992)
Warner
Instruments
A Harvard Apparatus Company .