Fast Capacitance Patch Clamp Technique
Influence of conductance changes on patch clamp capacitance measurements using a lock- in.. At correct phase setting, the artifacts in the capacitance measurement due to activation of linear conductances are small. The cross talk into the capacitance trace is well approximately by the second- order term in the Taylor expansion of the admittance. In the case of nonlinear current- voltage relationships, the measured conductance corresponds to the slope conductance in the range of the sine wave amplitude, and the cross talk into the capacitance trace corresponds to the second- order effect of the slope conductance. The finite gating kinetics of voltage- dependent channels generate phase- shifted currents.
EPC 7 PLUS Patch Clamp Amplifier. Manual adjustment of the fast and slow capacitance cancellation. C-fast: 0 to 10 pF, 0.5 to 5 . Patch clamp data acquisition and analysis software for Windows and. Patch-clamp is used to study all sorts of ionic channels and their regulations with measuring pA current of cell ionic channel,but the fast capacitance(C-fast)compensation and slow capacitance(C-slow)compensation transient.
These lead to major artifacts in the capacitance measurements when the angular frequency of the sine wave is close to the kinetic rate constant of the channel. However, when the channel kinetics are sufficiently slow, or sufficiently fast, the cross talk is still close to the second- order effect of the measured conductance. The effects of activation of voltage- dependent currents on the capacitance measurements may be estimated, provided a detailed characterization of the kinetics and voltage dependence is available. A phase error of the lock- in amplifier of a few degrees leads to significant projections. The phase- tracking method can be used to keep the phase aligned only during periods of low membrane conductance. However, nonideal properties of the equivalent circuit, in particular the fast capacitance between the pipette and the bath solutions, may lead to large phase errors when the phase- tracking method is used, depending on the electrical properties of the cell.
In this article we provide practical values, setting the range where possible artifacts are below defined limits. For proper evaluation of capacitance measurements, the capacitance and conductance traces should always be displayed together.
- Patch-clamp Capacitance Measurements and Ca 2+ Imaging at Single Nerve Terminals in Retinal Slices. A low pipette capacitance also helps the electronic C-fast (fast capacitance) compensation of the EPC-9 (or EPC-10).
- Patch-clamp is used to study all sorts of ionic channels and their regulations with measuring pA current of cell ionic channel, but the fast capacitance (C-fast) compensation and slow capacitance (C-slow) compensation.
- Influence of conductance changes on patch clamp capacitance measurements using a lock.
- Patch-Clamp Capacitance Measurements. Vesicle endocytosis requires dynamin-dependent GTP hydrosis at a fast CNS synapse.