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. 1978 Aug;75(8):3756–3760. doi: 10.1073/pnas.75.8.3756

Kinetic analysis of receptor-controlled tracer efflux from sealed membrane fragments

Julius Bernhardt 1, Eberhard Neumann 1
PMCID: PMC392865  PMID: 16592553

Abstract

A detailed kinetic analysis is presented for activator-receptor-mediated efflux of tracer substances from vesicular membrane systems in general and from sealed fragments of excitable membranes in particular. Rate constants and amplitudes, as the primary measurable quantities of the efflux kinetics, are expressed in terms of fundamental properties of vesicular membrane systems containing receptors of chemical gating systems. The experimental determination and theoretical analysis of single contributions to a complex receptor-controlled efflux has been treated for the acetylcholine receptor system; also the effect of “pharmacological densensitization” on efflux is explicitly formulated. The dependence of the measured efflux parameters on the concentration of activators can be used to derive the kinetic and thermodynamic constants for receptor activation and inactivation processes; a general kinetic scheme and two limiting cases are analyzed. The efflux of 22Na from “excitable microsacs” of Torpedo marmorata is treated as an example, and the power of the rigorous analytical method is demonstrated. In particular, the analysis of efflux amplitudes from only a few data points offers an alternative to the longer lasting measurements for obtaining efflux curves when a safety factor is involved, as in the case of tracer ions like 22Na.

Keywords: acetylcholine receptor, excitable membranes, pharmacological desensitization

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

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