Özer, Mahmut | Erdem, Rıza

Article | 2004 | Physica A: Statistical Mechanics and its Applications331 ( 01.Feb ) , pp.51 - 60

Dynamics of voltage-gated ion channels in the excitable cell membranes is formulated by the path probability method of nonequilibrium statistical physics and approaches of the system toward the steady or equilibrium states are presented. For a single-particle noninteractive two-state model, a first-order rate equation or dynamic equation is derived by introducing the path probability rate coefficients which satisfy the detailed balancing relation. Using known parameters for the batrachotoxin (BTX)-modified sodium channels in giand squid axon as an example, the rate equation is solved and voltage dependence of the time constant (?) a . . .nd its temperature effect are investigated. An increase in voltage caused a shift in ? towards shorter durations while increasing temperature caused a shift in time distribution towards longer durations. Results are compared with the kinetic model for the squid axon BTX-modified sodium channels by the cut-open axon technique and a very good agreement is found. © 2003 Elsevier B.V. All rights reserved Daha fazlası Daha az

Özer, Mahmut | Erdem, Rıza | Provaznik, Ivo

Article | 2004 | NeuroReport15 ( 2 ) , pp.335 - 338

Voltage-gated ion channels are of great importance in the generation and propagation of electrical signals in the excitable cell membranes. How these channels respond to changes in the potential across the membrane has been a challenging problem, and different approaches have been proposed to address the mechanism of voltage sensing and gating in these channels. In this study, we attempt a new approach by considering a simple two-state gate system and applying the path probability method to construct a nonequilibrium statistical mechanical model of the system. The model which is based on the principles of statistical physics provide . . .s a firm physical basis for ion channel gating. © 2004 Lippincott Williams & Wilkins Daha fazlası Daha az

Özer, Mahmut

Article | 2005 | Physica A: Statistical Mechanics and its Applications357 ( 03.Apr ) , pp.397 - 414

In this study, we propose a theoretical framework for the determination of rate kinetics in the ion channels. In this framework, we firstly formulate the kinetic equation for the time-dependent open-state probability of the gate and forward and backward rate kinetics based on the path probability method with three parameters, explicitly. Then, we construct a tool to determine if fitted rate kinetics satisfy the experimental data by deriving kinetic coefficients of activation and inactivation gates based on the Onsager reciprocity theorem. The proposed framework is based on the principles of statistical physics and conceptually quite . . . different from those of conventional models. We also illustrate its applicability based on the empirical inactivation kinetics of T-type calcium channel from thalamic relay neurons, and then compare it with the linear and nonlinear thermodynamic models for the same calcium channel. The results of the present study indicate that our methodology suggests a general framework for the determination of rate kinetics in ion channels. © 2005 Elsevier B.V. All rights reserved Daha fazlası Daha az