AUTHOR=Clay John R. TITLE=A Novel Method for the Description of Voltage-Gated Ionic Currents Based on Action Potential Clamp Results—Application to Hippocampal Mossy Fiber Boutons JOURNAL=Frontiers in Cellular Neuroscience VOLUME=9 YEAR=2016 URL=https://www.frontiersin.org/journals/cellular-neuroscience/articles/10.3389/fncel.2015.00514 DOI=10.3389/fncel.2015.00514 ISSN=1662-5102 ABSTRACT=

Action potential clamp (AP-clamp) recordings of the delayed rectifier K⁺ current I_K and the fast-activated Na⁺ current I_Na in rat hippocampal mossy fiber boutons (MFBs) are analyzed using a computational technique recently reported. The method is implemented using a digitized AP from an MFB and computationally applying that data set to published models of I_K and I_Na. These numerical results are compared with experimental AP-clamp recordings. The I_Na result is consistent with experiment; the I_K result is not. The difficulty with the I_K model concerns the fully activated current-voltage relation, which is described here by the Goldman-Hodgkin-Katz dependence on the driving force (V-E_K) rather than (V-E_K) itself, the standard model for this aspect of ion permeation. That revision leads to the second—a much steeper voltage dependent activation curve for I_K than the one obtained from normalization of a family of I_K records by (V-E_K). The revised model provides an improved description of the AP-clamp measurement of I_K in MFBs compared with the standard approach. The method described here is general. It can be used to test models of ionic currents in any excitable cell. In this way it provides a novel approach to the relationship between ionic current and membrane excitability in neurons.