Parasympathetic nervous system in nocturnal asthmaBr Med J (Clin Res Ed) 1988; 296 doi: https://doi.org/10.1136/bmj.296.6634.1427 (Published 21 May 1988) Cite this as: Br Med J (Clin Res Ed) 1988;296:1427
- J F J Morrison,
- S B Pearson,
- H G Dean
To investigate the effect of vagal blockade with atropine on nocturnal fall in peak expiratory flow rate 10 patients with asthma who had a diurnal variation in peak expiratory flow rate of >20% were given 30 μg/kg of intravenous atropine or a placebo at 4 am and 4 pm. Vagal blockade caused significant bronchodilatation at 4 am and 4 pm (peak expiratory flow rate rose from 260 to 390 l/min at 4 am and 400 to 440 l/min at 4 pm) and significantly increased the pulse rate from 60 to 121 beats/minute at 4 am and from 76 to 122 beats/minute at 4 pm.
Nocturnal asthma was almost totally reversed, implying that vagal mechanisms are fundamental in its pathophysiology. Other mechanisms—diurnal changes in plasma adrenaline concentration, the activity of non-adrenergic non-cholinergic nerves, and circadian rhythms of inflammatory mediator activity—may also be implicated.