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Clinical Research

Parasympathetic nervous system in nocturnal asthma

Br Med J (Clin Res Ed) 1988; 296 doi: (Published 21 May 1988) Cite this as: Br Med J (Clin Res Ed) 1988;296:1427
  1. J F J Morrison,
  2. S B Pearson,
  3. 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.

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