T. Metin Önerci (ed.)Nasal Physiology and Pathophysiology of Nasal Disorders201310.1007/978-3-642-37250-6_9© Springer-Verlag Berlin Heidelberg 2013
9. Nasal NO and Its Role in the Physiology of the Nose and Diagnosis
(1)
Department of Otorhinolaryngology, Head and Neck Surgery, University Hospitals Leuven, Herestraat 49, Leuven, 3000, Belgium
(2)
Department of Allergy and Rhinology, Royal National Throat, Nose and Ear Hospital, 330 Grays Inn Road, London, WC1X8DA, UK
Abstract
Since the last decade, growing attention has been paid to nitric oxide (NO) as a noninvasive marker of inflammation of the airways. Exhaled NO (eNO) measurement has become a routine diagnostic tool in monitoring lower airway inflammation, since it had been shown to be a noninvasive parameter of monitoring lower airway inflammation. However, most of the NO is being produced in the sinonasal cavities, without clear insight into its precise role in upper airway homeostasis. Nasal NO (nNO) may be involved in the innate antibacterial effects of the airway mucosa, regulation of ciliary beat frequency, and/or local regulation of blood flow. In addition, nNO is believed to contribute to lower airway homeostasis. The measurement of nNO is nowadays a good screening test for primary ciliary dyskinesia and, therefore, has diagnostic value.
Keywords
Nitric oxidenasal homeostasisPathophysiologyCore Messages
NO is a gas primarily produced within the paranasal sinus cavities, playing a role in airway homeostasis.
Nasal NO levels may be normal, increased, or decreased in upper airway diseases.
Nasal NO represents a screening test for primary ciliary dyskinesia.
9.1 Introduction
Since the last decade, growing attention has been paid to nitric oxide (NO) as a noninvasive marker of inflammation of the airways. Exhaled NO (eNO) measurement has become a routine diagnostic tool in monitoring lower airway inflammation, since it had been shown to be a noninvasive parameter of monitoring lower airway inflammation (Alving et al. 1993). However, most of the NO is being produced in the sinonasal cavities, without clear insight into its precise role in upper airway homeostasis. Nasal NO (nNO) may be involved in the innate antibacterial effects of the airway mucosa, regulation of ciliary beat frequency, and/or local regulation of blood flow. In addition, nNO is believed to contribute to lower airway homeostasis. The measurement of nNO is nowadays a good screening test for primary ciliary dyskinesia and, therefore, has diagnostic value.
9.2 Nitric Oxide (NO)
Nitric oxide (NO) is a colorless and odorless gas that is present in air exhaled through the mouth or nose. NO is produced from arginine and oxygen by nitric oxide synthase (NOS) (Scadding and Scadding 2009). Constitutively expressed neuronal and endothelial forms exist as well as an induced form, iNOS, which appears to be upregulated within the respiratory tract in response to pro-inflammatory signals. NO came to prominence for its role in vasodilatation and subsequently as a neurotransmitter and inflammatory mediator. The role of NO in the airways is complex (Scadding 2007), possibly including antibacterial effects, pro-inflammatory effects, and regulation of blood flow and ciliary beat frequency. Exhaled NO (eNO) levels are raised in eosinophilic asthma, and measurement of this has become a standardized, but not yet widespread, tool in diagnosis and management of asthma. It can potentially provide a rapid, low-cost, objective measure of lower airway inflammation.
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