Ionic Channels for Signal Transmission and Propagation

Abstract

Publisher Summary The ability to propagate and transmit signals is conferred to neurons by proteins embedded in the lipid membrane. Knowledge of the molecular properties of these macromolecules would therefore provide a sound basis for the understanding of neuronal functions. A great deal of information on such molecular functions has been provided by two recently developed electrophysiological techniques: noise analysis and single channel recording. Both these techniques allow the study of integral proteins that are assumed to function as so-called ionic channels or membrane pores regulating the flow of ions across the membrane. As such, these proteins must span the whole membrane thickness, and provide a hydrophilic pathway across the membrane. Noise analysis works on the macroscopic fluctuations in membrane current that result from the statistical superposition of many microscopic unit responses. Exploiting some fundamental laws of statistics it deduces from the macroscopic fluctuations the properties of the elementary units that constitute them. Noise analysis is applicable to a wider range of preparations and experimental conditions; however, it depends on certain assumptions, the validity of which, in turn, has to be proven by single channel recording. This chapter provides a summary of some of the molecular features of ionic channels encountered in nerve and nerve-like cells. The chapter focuses on results obtained by single channel recording. Where necessary, it also includes noise results.