Ca2+ permeability of nicotinic acetylcholine receptors

Nicotinic acetylcholine receptors (nAChRs) are expressed in muscle cells and neurons, as well as in an increasing number of other cell types. The nAChR channels are permeable to cations, including Ca²⁺. Ca²⁺ entry through nAChR channels has been shown to modulate several Ca²⁺-dependent cellular processes, such as neurotransmitter release, synaptic plasticity, and cell motility. The value of Ca²⁺ permeability associated to a particular nAChR subtype thus represents an important indication for its physiological role. This review summarizes the quantitative data on Ca²⁺ permeability obtained from several nAChR subtypes in native and heterologous systems. Different experimental approaches are compared, and the structural determinants of Ca²⁺ permeability are discussed.