LOCALIZATION OF CHOLINERGIC NERVES IN LOWER AIRWAYS OF GUINEA-PIGS USING ANTISERA TO CHOLINE-ACETYLTRANSFERASE

Primary antiserum to choline acetyltransferase (ChAT), a specific mark er for cholinergic nerves, was used to characterize the distribution o f cholinergic nerve fibers and nerve cell bodies in guinea pig airways . ChAT immunoreactive nerve fibers were localized to the smooth muscle throughout the conducting ah-ways and in the lamina propria of the tr achea and large bronchi. Likewise, all nerve cell bodies in the gangli a intrinsic to the trachea and bronchi displayed a cholinergic phenoty pe. By contrast, ChAT immunoreactive nerve fibers were infrequently se en in the lamina propria of the peripheral airways and were absent in the airway epithelium. No evidence for colocalization of ChAT and the enzyme synthesizing the putative relaxant neurotransmitter nitric oxid e was observed. These results provide further evidence for the key rol e played by cholinergic nerves in regulating airway smooth muscle tone and bronchial blood flow and provide further evidence that acetylchol ine is not coreleased with the neurotransmitter(s) mediating relaxatio ns of airway smooth muscle.