Dresden 2017 – wissenschaftliches Programm
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BP: Fachverband Biologische Physik
BP 42: Neurosciences
BP 42.3: Vortrag
Mittwoch, 22. März 2017, 15:45–16:00, ZEU 250
Protocol for fluctuation analysis of ion channel currents in nonstationary conditions: application to Ca2+ channels — •Christian Scheppach1,2 and Hugh P.C. Robinson2 — 1Physikalisches Institut, Albert-Ludwigs-Universität Freiburg i. Br., Germany — 2Department of Physiology, Development and Neuroscience, University of Cambridge, U.K.
Fluctuation analysis is a method which allows measurement of the single channel current of ion channels even when it is too small to be resolved directly with the patch clamp technique. The method in its original form depends on stationary conditions, such that meaningful ensemble-averaging over several successive current traces can be performed. However, experimentally this is sometimes not possible, for example when the ion channel current runs down rapidly. We therefore developed a novel fluctuation analysis protocol which extracts information from individual current traces. It is based on voltage ramp stimulation, mean current fitting of individual current responses and band-pass filtering. We apply the method to Ca2+ channels in pyramidal neurons of layer 5 of rat neocortex, arriving at a single-channel current of 0.07 pA (membrane potential: −20 mV; external Ca2+ concentration: 2 mM). We validate the accuracy of the method by analysing simulated data and compare it with another established method of dealing with ion channel rundown.
Reference: C. Scheppach & H.P.C. Robinson (arXiv, under review).