Extended observation of the nasal cycle using a portable rhinoflowmeter.

OBJECTIVE: Nasal patency varies owing to the effects of humidity, temperature, and exercise. In addition, periodic cycles of congestion and decongestion that alternate between the right and the left side of the nose, which are termed the "nasal cycle," have been observed. The physiologic mechanisms underlying this cycle are not clear. Sympathetic nerves that supply the nose are regulated by the hypothalamus and the vasomotor areas of the brainstem. It is possible that the nasal cycle could be involved in protection against respiratory infection or allergies. Conventional methods of studying the nasal cycle, including rhinomanometry and acoustic rhinometry, impose limitations on the location and timing of evaluation. We studied the nasal cycle using a new portable device for relatively long-term rhinoflowmetry. METHODS: Twenty normal subjects aged 24 to 77 years were fitted with the portable rhinoflowmeter (Rhinocycle, Rhinometrics, Lynge, Denmark) to continuously measure nasal air flow via each nostril over 12 daytime hours. RESULTS: No subject complained of discomfort owing to the device, and 14 of them showed a detectable nasal cycle. The mean nasal cycle duration was 110 minutes, although variation was considerable, even in a single subject. CONCLUSIONS: The portable device proved useful for observing the nasal cycle, and it should be valuable for the general investigation of nasal physiology.

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.