Neuronal acetylcholine receptor channels from insects: a comparative electrophysiological study.

The channel properties of nicotinic acetylcholine receptor subtypes in the nervous system of insects (Locusta migratoria) have been characterized. Single channel measurements were performed using patch-clamp techniques as well as planar lipid bilayer reconstitution approaches. In reconstitution experiments using receptor-preparations isolated from neuronal membranes by alpha-toxin affinity chromatography, a ligand-gated channel type was found, which showed a high conductance and a short mean lifetime. Patch-clamp experiments on synapse-free somata of isolated nerve cells revealed an acetylcholine-gated channel type with a lower conductance but a longer lifetime. The two different agonist-activated channel types are supposed to represent synaptic and extrasynaptic acetylcholine receptors.