© 2003 American Thoracic Society DOI: 10.1165/rcmb.2002-0190OC Expression of the High-Affinity Choline Transporter, CHT1, in the Rat TracheaInstitutes for Anatomy and Cell Biology, Justus-Liebig-University, Giessen; and Philipps-University, Marburg, Germany Address correspondence to: Dr. Uwe Pfeil, Institute for Anatomy and Cell Biology, Aulweg 123, 35385 Giessen, Germany. E-mail: uwe.pfeil{at}anatomie.med.uni-giessen.de The rate limiting step in neuronal acetylcholine (ACh) synthesis is the uptake of choline by the high-affinity choline transporter (CHT1). Here, we investigated the distribution of CHT1 in the rat trachea. CHT1-mRNA was detected by reverse transcriptase–polymerase chain reaction in trachea without epithelium, abraded tracheal mucosa, and in epithelial cells obtained by laser-assisted cell-picking. Accordingly, CHT1-mRNA could also be detected in tracheal epithelial cells by in situ hybridization. Recently obtained polyclonal rabbit and guinea-pig antisera against a synthetic peptide corresponding to amino acid residues 29–40 of the rat CHT1 sequence localized CHT1 protein in combination with antisera against the vesicular acetylcholine transporter in cholinergic fibers innervating tracheal glands and the tracheal muscle. In case of the tracheal epithelium, CHT1 was restricted to the apical membrane of the ciliated cells, as demonstrated by confocal laser scanning and electron microscopy using an affinity-purified CHT1 antiserum. The close apposition of CHT1 to reported sites of localization of choline acetyltransferase in these cells is strongly in favor of ACh synthesis being fuelled by choline uptake via CHT1 after release and breakdown of ACh at the luminal surface. Accordingly, cholinergic regulation of tracheal epithelial function is governed by local release and recycling of ACh by ciliated cells.
Abbreviations: acetylcholine, ACh • high-affinity choline transporter, CHT • choline acetyltransferase, ChAT • digoxygenin, DIG • polymerase chain reaction, PCR • reverse transcriptase, RT • Tris-buffered saline with 0.05% Tween-20, TTBS • vesicular acetylcholine transporter, VAChT This article has been cited by other articles:
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