Immunohistochemical Localization of Subtypes of Muscarinic Receptors in Human Inferior Turbinate Mucosa

The regulation of glandular secretions and vasomotor tone in human nasal mucosa implicates muscarinic receptors. There are 5 recognized classes (m1 through m5) of muscarinic receptor subtypes, and the aim of our study was to localize muscarinic receptor subtypes (m1 through m5) in human inferior turbinate mucosa by an immunohistochemical method. We found m1 and m2 receptors distributed on glands, arteries, veins, and epithelia; m4 receptors were found around arteries; and m5 receptors were identified on glands and arteries. We found m3 receptors to be the most extensively distributed on glands, arteries, and veins of all of the muscarinic receptor subtypes. The m3 receptor is probably important in the physiology of the human inferior turbinate. This study may help identify the best target for more selective muscarinic drugs and guide the treatment of allergic and nonallergic rhinitis.