Address for correspondence: Ellis Cooper, Ph.D., Department of Physiology, McGill University, McIntyre Medical Science Building, 3655 Promenade Sir William Osler, Montreal, Quebec, Canada H3G 1Y6. Voice: 514-398-4334; fax: 514-398-7452.
Ecooper{at}med.mcgill.ca
Nicotinic acetylcholine receptors (nAChRs) play an important
role in various processes involved in regulating systemic blood
pressure. These receptors are expressed at excitatory cholinergic
synapses between sympathetic preganglionic neurons and postganglionic
sympathetic neurons and link the integrative activities of the
CNS with peripheral effector mechanisms of the sympathetic nervous
system. Nicotinic AChRs are also expressed on a subset of vagal
afferent neurons, including those involved in baroreceptor reflexes.
This review discusses the developmental expression of nAChRs
on vagal afferent neurons and two factors that influence the
differentiation of these neurons: ganglionic satellite cells
and neurotrophins. In addition, this review discusses two important
properties of neuronal nAChRs: inward rectification and calcium
permeability. At the molecular level, intracellular polyamines,
acting as gating particles, effectively block the receptor pore
in a voltage-dependent manner, producing inward rectification.
Moreover, a critical structural determinant underlies both the
block by intracellular polyamines and calcium permeability.
Finally, this review discusses the modulation and block of neuronal
nAChRs by extracellular polyamines and the possible implications
for neurodegenerative diseases.
