Molecular Basis and Thermodynamics of Bioelectrogenesis

ISBN-13: 9780792309758 / Angielski / Twarda / 1990 / 182 str.

Ernest Schoffeniels; D. Margineanu; E. Schoffeniels

Opis

Despite the fact that many years have elapsed since the first microcalorimetric measurements of an action potential were made, there is still among the research workers involved in the study of bioelectrogenesis a complete overlooking of the most fundamental principle governing any biological phenomenon at the molecular scale of dimension. This is surprising, the more so that the techniques of molecular biology are applied to characterize the proteins forming the ionic conducting sites in living membranes. For reasons that are still obscure to us the molecular aspects of bioelectrogenesis are completely out of the scope of the dynamic aspects of biochemistry. Even if it is sometimes recognized that an action potential is a free energy-consuming, entropy-producing process, the next question that should reasonably arise is never taken into consideration. There is indeed a complete evasion of the problem of biochemical energy coupling thus reducing the bioelectrogenesis to only physical interactions of membrane proteins with the electric field: the inbuilt postulate is that no molecular transformations, in the chemical sense, could be involved.

Spis treści

I The Description in Physico-Chemical Terms of Nervous System Properties.- I.1. Living systems as dissipative structures with local quasi equilibrium.- I.1.1. The creation of order by fluctuations.- I.1.2. Local quasi-equilibrium.- I.2. Information flows in living systems.- I.2.1. Measure of the amount of information.- I.2.2. The amount of information transmitted through trains of nerve impulses.- I.3. Evolution of the ideas about bioelectrogenesis. A brief account.- I.3.1. Prehistory of the study of excitability.- I.3.2. Nerve impulse as bioelectric event.- I.3.3. Studies of non-electric aspects of the nerve impulse.- I.3.4. Reception and transmission of excitation between cells.- References.- II Cell Membranes and Bioelectrogenesis.- II.1. The ubiquitous cellular component.- II.2. Membrane molecular components and their dynamics.- II.3. Silent and excitable membranes.- References.- III Phenomenological Aspects of Bioelectricity.- III.1. Resting potential of the cells.- III.1.a. Equilibrium transmembrane potentials.- III.1.b. Steady-state nonequilibrium transmembrane potential.- III.2. The passive propagation of potential changes. Axons as electric cables.- III.2.a. Membrane time and length constants.- III.2.b. Electrotonic propagation.- III.3. Regenerative propagation of action potentials in excitable membranes.- III.3.a. Ionic pathways in the axonal membranes.- III.4. Intercellular transmission of excitation.- III.4.a. Main events in chemical synaptic transmission.- III.4.b. Post-synaptic potentials.- III.5. An overview of bioelectric phenomena.- References.- IV Molecular Approaches of Bioelectricity.- A. Intermediary metabolism in brain.- B. Control of glycolysis.- C. Non oxidative consumption of glucose during neural activity.- D. The pentose shunt.- E. The amino acids pool.- F. Concluding remarks.- References.- V Puzzle of Nerve Impulse Thermodynamics.- V.1. Oxygen consumption and heat production inactive nerve.- V.2. Energy dissipation by Na+/K+ pumps in nerves.- V.3. Energy changes during the action potential.- V.3.a. Ionic dissipation of energy.- V.3.b. Capacitive energy changes.- V.3.c. Energetics of ionic conducting sites transitions.- V.4. Thermodynamic inconsistency of the kinetics of n, m and h parameters.- References.- VI Thiamine Triphosphate as the Specific Operative Substance in Spike-Generation.- Conclusion.- References.- VII. Merging Electrophysiology and Molecular Approaches.- VII.1. Single-channel recording.- VII.2. The structure of channel proteins.- VII.3. From molecular mechanisms to complex brain functions.- VII.4. Levels of unitary events.- References.- Index of Names.- Index of Subjects.