title: The estimation of rapid rate constants from current-amplitude frequency distributions of single-channel recordings.
abstract: A method is described for estimating rapid rate constants from the distributions of current amplitude observed in single-channel electrical recordings. It has the advantages over previous, similar approaches that it can accommodate both multistate kinetic models and adjustable filtering of the data using an 8-pole Bessel filter. The method is conceptually straightforward: the observed distributions of current amplitude are compared with theoretical distributions derived by combining several simplifying assumptions about the underlying stochastic process with a model of the filter and electrical noise. Parameters are estimated by approximate maximum likelihood. The method was used successfully to estimate rate constants for both a simple two-state kinetic model (the transitions between open and closed states during the rapid gating of an outward-rectifying K(+)-selective channel in the plasma membrane of Acetabularia) and a complex multistate kinetic model (the blockade of the maxi cation channel in the plasma membrane of rye roots by verapamil). For the two-state model, parameters were estimated well, provided that they were not too fast or too slow in relation to the sampling rate. In the three-state model the precision of estimates depended in a complex way on the values of all rate parameters in the model.
authors.affiliation: Department of Cell Physiology, Horticulture Research International, Warwick, UK.
authors.forename: P J
authors.initials: PJ
authors.lastname: White
authors.forename: M S
authors.initials: MS
authors.lastname: Ridout
mesh_terms: D000076:Acetabularia / Q000502:physiology; D002121:Calcium Channel Blockers / Q000494:pharmacology; D002462:Cell Membrane / Q000502:physiology; D004594:Electrophysiology / Q000379:methods; D015640:Ion Channel Gating; D007473:Ion Channels / Q000037:antagonists & inhibitors / Q000502:physiology*; D007700:Kinetics; D008954:Models, Biological; D018517:Plant Roots / Q000502:physiology; D015221:Potassium Channels / Q000502:physiology; D012434:Secale / Q000502:physiology; D014700:Verapamil / Q000494:pharmacology
chemical_list: D002121:Calcium Channel Blockers; D007473:Ion Channels; D015221:Potassium Channels; D014700:Verapamil