Electrophysiological Recordings Polarizable A 100 mM KCl 10 mM KCI K permselective membrane 10 mM KCI 100 mM KCI≠
V A B 100 mM KCl 10 mM KCl K+ permselective membrane I 10 mM KCl 100 mM KCl I V I V Unpolarizable electrodes Electrophysiological Recordings
a cell membrane with a specific permeability and also electrical properties channels are proteins in a lipidic environment 0 mv -90-60mV
-90/-60 mV 0 mV A cell membrane with a specific permeability and also electrical properties: channels are proteins in a lipidic environment
Resting potential Ionic equilibria RTLIK Ek=1 ZF KTI
Resting Potential • Ionic Equilibria i o K K Z E [ ] [ ] ln F RT K + + =
Nernst equation RT,KI K ZF K
Nernst equation i o K K ZF RT E [ ] [ ] K ln + + =
Neuron type Size Technique History Big cylindrical axons mm Metal electrodes K. Cole And channel concept 1940s A. Hodgkin Small myelinated axons 1-5 um Sucrose gap huxley 1950s Large neurons molluscs 500um Glass electrode Ling 1949 motoneurones 75u recording Medium size neurons <20um Hold and sample Small neurons And other cells B Sakmann 5-10um Patch-clamp And e neher And channels 1992
Big cylindrical axons And channel concept Small myelinated axons Large neurons molluscs motoneurones Medium size neurons Small neurons And other cells And Channels ~ 1mm 1-5 µm 500 µm 75 µm < 20 µm 5-10 µm Metal electrodes Patch-clamp Sucrose gap Glass electrode recording K. Cole 1940s A. Hodgkin & Huxley 1950s Hold and Sample B. Sakmann And E. Neher 1992 Neuron type Size Technique History Ling 1949