Royal Society Publishing

Relaxation and Fluctuations of Membrane Currents that Flow through Drug-Operated Channels

D. Colquhoun , A. G. Hawkes


The theoretical background is presented for (a) the relaxation towards equilibrium of drug-induced membrane currents, and (b) the fluctuations of membrane current about its equilibrium value that originate in the opening and closing of membrane ion channels. General expressions are given that relate the relaxation current, autocovariance function, spectral density function, fluctuation variance and mean open channel lifetime to the rate constants and single channel conductances for any theory of drug action based on the law of mass action. The question of how much can be validly inferred from experimental spectra that appear to have only one component is discussed. The equations are illustrated by their application to some simple theories of drug action that are currently under consideration.

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