Activation and desensitization of heteromeric neuronal nicotinic receptors: implications for non-synaptic transmission

Consideration of the activation and desensitization properties of neuronal nicotinic acetylcholine receptors (nAChRs) predicts that there should be a range of concentrations over which low ambient levels of agonist can continuously open nAChR channels. These findings support the idea that postsynaptic nAChRs may participate in unconventional cellular signaling mediated by the release of acetylcholine from diffusely distributed non-synaptic cholinergic varicosities.