Multiple nicotinic acetylcholine receptora α-subunits are expressed in the arterial system of the rat

Neuronal nicotinic acetylcholine receptors (nAChRs) are hetero- and homopentamers built up by nine different α-subunits and three different α-subunits. The subtype composition within the receptor determines ligand specificity, affinity and cation permeability. In this study we focused on the distribution of the ligand binding α-subunits in the rat arterial system by means of RT-PCR and immunohistochemistry. Subtypes α3, α5, α7 and α10 were found to be expressed by endothelial cells, suggesting that they are equipped both with calcium-preferring (α7 homopentamers) and monovalent cation-preferring (heteropentamers containing α3- and α5-subunits) nAChR channels. All α-subtypes except α9 were expressed by vascular smooth muscle cells with a highly specific distribution pattern along the vascular tree. While every α-subunit except α9 was detected in the thoracic aorta, intrapulmonary arterial branches contained only α7 immunoreactivity, and other vascular beds held intermediate positions with respect to the extent of α-subunit expression. Current knowledge does not allow to correlate these distribution patterns to specific functions, but it can be anticipated that at least some components of nAChR-mediated signalling in the arterial wall are highly specific for individual arteries.