Electrical Potentials in Biological Membrane Transport

ISBN-13: 9783642816772 / Angielski / Miękka / 2011 / 88 str.

E. Heinz

Opis

The material of this volume was originally planned to be incorporated in the preceding monograph Mechanics and Energetics of Biological Transport. A separate and coherent treatment ofthe variety of bioelectrical phenomena was considered preferable, mainly for didactic reasons. Usually, the biologist has to gather the principles of bioelectricity he needs from different sources and on different levels. The present book intends to provide these principles in a more uniform context and in a form adjusted to the problems of a biol ogist, rather than of a physicist or electrical engineer. The main emphasis is put on the molecular aspect by relating the bioelectrical phenomena, such as the membrane diffusion potentials, pump potentials, or redox potentials, to the properties of the membrane concerned, and, as far as pOSSible, to specific steps of transport and metabolism of ions and nonelectrolytes. Little space is devoted to the familiar and widely used representation of bioelectrical phe nomena in terms of electrical networks, of equivalent circuits with batteries, resistances, capacities etc. In order to elucidate the basic principles, the formal treatment is kept as simple as pOSSible, using highly Simplified models, based on biological systems. The corresponding equations are derived in two ways: kinetically, i. e. in terms of the Law of Mass Action, as well as energetically, i. e., in terms of Nonequilibrium Thermodynamics."

Spis treści

1 Origin of Electrical Potentials.- 1.1 Equilibrium Potentials.- 1.1.1 The Gibbs-Donnan Potential.- 1.1.2 Surface Potentials (Phase Boundary Potentials).- 1.2 Membrane Diffusion Potentials.- 1.2.1 General.- 1.2.2 Systems with One Electrolyte.- 1.2.3 Systems with Several Electrolytes.- 1.2.3.1 Approximation Approaches.- 1.2.3.2 The Statistical Approach.- 1.2.3.3 The Goldman-Hodgin-Katz Equation.- 1.2.4 Stabilization of Membrane Diffusion Potential Differences.- 1.3 Electrogenic Pump Potentials.- 1.3.1 General.- 1.3.2 Formal Treatment of Pump PD’s.- 1.3.2.1 Treatment in Terms of the Law of Mass Action (LMA).- 1.3.2.2 Treatment in Terms of Thermodynamic of Irreversible Processes (TIP).- 1.4 Membrane Potentials in Secondary Active Transport.- 1.4.1 Ionic Symporters and Antiporters.- 1.4.2 Ion-linked Cotransport of Organic Solutes.- 1.5 Redox Potentials in Membrane Transport.- 2 Control of Electric Potentials — Maintenance and Modulation.- 2.1 Physiological Mechanisms.- 2.2 Experimental Modulations of PD.- 2.2.1 Replacement of Permeant Ion Species.- 2.2.2 Ionophores.- 2.2.2.1 Carrier-like and Channel-like Ionophores.- 2.2.2.2 Rheogenic and Non-Rheogenic Ionophores..- 2.2.2.3 The Electric PD Under the Influence of Ionophores.- 2.2.3 Channel Blockers.- 2.2.4 Modulating and Mimicking Electrogenie Pumps.- 3 Some Problems Associated with the Measurement of Electric Membrane Potentials.- 3.1 General.- 3.2 Microelectrodes.- 3.3 Distribution of Passive Permeant Ions.- 3.4 Fluorescent Dyes.- 3.5 Other Membrane Probes.- References.