Ionic channels in excitable membranes. Current problems and biophysical approaches

Ionic channels in excitable membranes. Current problems and biophysical approaches.

Ionic channels are gated aqueous pores whose conformational changes are driven by the electric field in the membrane. Gating may be studied by three electrical methods: ionic current transients, ionic current fluctuations, and "gating current," and probably occurs through a series of conformational changes in the channel leading to an all-or-nothing opening of the pore. When the potential is he...

Ionic Channels in Biological Membranes

ABSRACT Ionic channels are proteins with holes down their middle that control access to biological cells and thus govern an enormous range of biological functions important in health and disease. A substantial fraction of the drugs used in clinical medicine act directly or indirectly on channels. Channels have a simple well defined structure, and the fundamental mechanism of ionic motion is kno...

Evolution of ionic channels of biological membranes.

This paper presents a view of the evolution and phylogenetic distribution of ionic channels of biological membranes. The view is based on the assumptions that ionic channels (1) appeared very early in the history of life, (2) have evolved from a common ancestor, and (3) have been subjected to evolutionary pressure to reach precision and high speed of signaling. We propose that Ca2+ was the intr...

Electrodiffusion Model of Rectangular Current Pulses in Ionic Channels of Cellular Membranes

A simplified electrodiffusion model for rectangular current pulses in ionic channels of biological membranes is presented. Numerical simulations and a dynamical systems analysis of traveling wave solutions in the model indicate that the durations and separations of current pulses vary stochastically in time, as is observed experimentally. An electrodiffusion theory of the mechanism for gating i...

Proteins in excitable membranes.