Rat arteries contain multiple nicotinic acetylcholine receptor a-subunits Do ¨rthe Bru ¨ggmann, Katrin S. Lips, Uwe Pfeil, Rainer V. Haberberger, Wolfgang Kummer * Institute for Anatomy and Cell Biology, Justus-Liebig-University, Aulweg 123, 35385 Giessen, Germany Abstract We investigated the occurrence and distribution of the ligand-binding a-subunits of nicotinic acetylcholine receptors in the rat arterial system in situ by means of RT-PCR and immunohistochemistry. Except the a9-subunit, all other mammalian non-muscular a-subunits were expressed in the arterial wall - either in endothelial or in smooth muscle cells - suggesting it as a direct target of nicotine and endogenous acetylcholine. The distribution pattern of a-subunits found in smooth muscle cells varied considerably among the individual elastic, muscular and intraparenchymal arteries investigated, suggesting that non-neuronal cholinergic signalling via nicotinic receptors in the vascular wall includes components that are highly specific for individual arteries. D 2003 Elsevier Science Inc. All rights reserved. Keywords: Acetylcholine; Cholinergic receptors; Immunohistochemistry Introduction Nicotine is considered to be the main pathogenic compound of cigarette smoke that causes vascular diseases. It addresses a family of hetero- or homopentameric acetylcholine receptors. Outside the motor endplate, these nicotinic acetylcholine receptors (nAChRs) consist of ligand-binding a-subunits and partly, depending on subtype combination, additional h-subunits. In mammals, 8 extra-muscular a- subunits (a2–7, a9–10; a8 has been described only in chicken) have been identified [1,2]. Since most arteries lack a cholinergic innervation, nicotine-induced vascular alterations have often been ascribed to 0024-3205/03/$ - see front matter D 2003 Elsevier Science Inc. All rights reserved. doi:10.1016/S0024-3205(03)00067-5 * Corresponding author. Tel.: +49-641-99-47000; fax: +49-641-99-47009. E-mail address: wolfgang.kummer@anatomie.med.uni-giessen.de (W. Kummer). www.elsevier.com/locate/lifescie Life Sciences 72 (2003) 2095 – 2099