van Aalderen W M, Meijer G G, Oosterhoff Y, Bron A O
Department of Paediatric Pulmonology, Beatrix's Childrens Hospital, Groningen, The Netherlands.
Respir Med. 1993 Aug;87 Suppl B:37-9.
Nocturnal symptoms are common in asthma, even when patients are regularly seen at an outpatient clinic. Inflammation is generally accepted as a general feature of asthma and the severity of this basic inflammatory process can be increased by exogenous triggers such as exposure to allergens and nonallergic stimuli. Superimposed endogenous circadian rhythms may play a more important and intricate role in the circadian modulation of the inflammatory process by changing the number of cells, their release of mediators and/or the susceptibility of airway smooth muscle and vasculature. For instance, an increase in vagal tone may induce nocturnal bronchoconstriction which is further enhanced by falling catecholamine levels. Together, the reduced nocturnal catecholamine levels and the diminished bronchodilating capacity of the NANC system and the low cortisol levels oppose possible protection against inflammatory processes leading to nocturnal airflow obstruction.
夜间症状在哮喘中很常见，即使患者定期在门诊就诊。炎症通常被认为是哮喘的一个普遍特征，这种基本炎症过程的严重程度会因外源性触发因素而增加，如接触过敏原和非过敏性刺激物。叠加的内源性昼夜节律可能在炎症过程的昼夜调节中发挥更重要和复杂的作用，通过改变细胞数量、它们释放的介质和/或气道平滑肌和血管系统的敏感性。例如，迷走神经张力增加可能会诱发夜间支气管收缩，而儿茶酚胺水平下降会进一步加剧这种收缩。此外，夜间儿茶酚胺水平降低、非肾上腺素能非胆碱能（NANC）系统的支气管舒张能力减弱以及皮质醇水平较低，这些因素共同作用，阻碍了对导致夜间气流阻塞的炎症过程的潜在保护作用。
