Application of oscillating potentials to the Shaker potassium channel.
Nonequilibrium response spectroscopy (NRS) has been proposed recently to complement standard electrophysiological techniques used to investigate ion channels. It involves application of rapidly oscillating potentials that drive the ion channel ensemble far from equilibrium. It is argued that new, so far undiscovered features of ion channel gating kinetics may become apparent under such nonequilibrium conditions. In this paper we explore the possibility of using regular, sinusoidal voltages with the NRS protocols to facilitate Markov model selection for ion channels. As a test case we consider the Shaker potassium channel for which various Markov models have been proposed recently. We concentrate on certain classes of such models and show that while some models might be virtually indistinguishable using standard methods, they show marked differences when driven with an oscillating voltage. Model currents are compared to experimental data obtained for the Shaker K+ channel expressed in mammalian cells (tsA 201).
Loyola University, Physics Department, New Orleans, LA 70118, USA. akargol@loyno.edu
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Kargol
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Hosein-Sooklal
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Constantin
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Przestalski
D002460:Cell Line; D003198:Computer Simulation; D004558:Electric Stimulation; D006706:Homeostasis / Q000502:physiology; D006801:Humans; D007668:Kidney / Q000502:physiology; D008390:Markov Chains; D008564:Membrane Potentials / Q000502:physiology*; D008954:Models, Biological; D015233:Models, Statistical; D009991:Oscillometry / Q000379:methods*; D018408:Patch-Clamp Techniques / Q000379:methods*; D015221:Potassium Channels / Q000502:physiology*; D011994:Recombinant Proteins / Q000378:metabolism; D051637:Shaker Superfamily of Potassium Channels; D013057:Spectrum Analysis / Q000379:methods*
D015221:Potassium Channels; D011994:Recombinant Proteins; D051637:Shaker Superfamily of Potassium Channels