BIO304H5 Chapter Notes - Chapter 8: Bert Sakmann, Patch Clamp, Voltage Clamp
Document Summary
How do macroscopic currents relate to single channel currents: erwin neherand bert sakmann , invented the patch clamp technique, permitsrecording of single ion channel currents! Consolidating single channel currents with multi-channel macroscopic currents: in h&h"s squid axon, recorded macroscopic currentswere the sum single channel currentsof all navand kvchannels expressed in the neuron/axon. Single navchannel currents add up to the macroscopic current with rapid activation and inactivation. Single kvchannel currents add up to the macroscopic current with slow activation and no inactivation. Depolarization causes single channels to open and close over time: as with macroscopic currents,downmeans inward current, upmeans outward current. Hodgkin and huxley noted in their voltage clamp experiments that at first, depolarization caused an increase in peakmacroscopic inaamplitude. However, with even stronger depolarization, they found that peak. Inamaxed out, and began to decline: eventually, peak inareached zero and reversed. At first, na+currents got bigger because increased depolarization activated more and more navchannels (i. e. gna)
