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Parasympathetic nervous system in nocturnal asthma.
J F Morrison1, S B Pearson, H G Dean
1Pulmonary Function Laboratory, Killingbeck Hospital, Leeds.
British Medical Journal (Clinical Research Ed.)
|May 21, 1988
Summary
Vagal blockade using atropine significantly improved lung function in asthma patients during nighttime, reversing nocturnal asthma symptoms. This suggests that vagal mechanisms play a crucial role in the pathophysiology of nighttime asthma.
Area of Science:
- Pulmonology
- Pharmacology
- Physiology
Background:
- Nocturnal asthma, characterized by a significant drop in peak expiratory flow rate (PEFR) during the night, significantly impacts asthma patients' quality of life.
- The underlying mechanisms of nocturnal asthma are not fully understood, but vagal nerve activity is suspected to play a role.
Purpose of the Study:
- To investigate the effect of vagal blockade with atropine on the nocturnal decline in peak expiratory flow rate (PEFR) in patients with asthma.
Main Methods:
- Ten asthma patients with >20% diurnal PEFR variation received intravenous atropine (30 µg/kg) or placebo at 4 am and 4 pm.
- Peak expiratory flow rate (PEFR) and pulse rate were monitored.
Main Results:
- Vagal blockade with atropine resulted in significant bronchodilation at 4 am and 4 pm, increasing PEFR from 260 to 390 L/min and 400 to 440 L/min, respectively.
- Pulse rate significantly increased post-atropine administration.
- Nocturnal asthma symptoms were almost completely reversed.
Conclusions:
- Vagal mechanisms are fundamental in the pathophysiology of nocturnal asthma.
- Other factors like diurnal changes in adrenaline, non-adrenergic non-cholinergic nerve activity, and circadian rhythms of inflammatory mediators may also contribute to nocturnal asthma.