The Effect of Asthma on Complexity Breathing Pattern in Asthma Rat Model

Asthma is a common chronic respiratory disease with reversible narrowing of the airways. Human studies show that breathing pattern and airway hyper-responsiveness have been changed in the course of the asthma disease. So, this study aimed to assess breathing patterns in normal and asthmatic rats. We assigned animals to one of two protocols: Saline and ovalbumin (asthmatic rats). Using body box plethysmography, animal respiration was recorded before and after each protocol. Then, respiratory rate, respiratory volume and inter-breath interval was quantified by non-linear analysis in MATLAB. To verify asthma, we evaluated hyper-responsiveness and bronchoalveolar lavage fluid after completion of the challenges. In order to evaluate hyper-responsiveness to methacholine, the animals were anesthetized and tracheostomy was done on them. Then the animals were connected to ventilator after their skeletal muscle were paralyzed. Hyper-responsiveness was measured at a distance of 6 minutes, after inhalation of doses of 0/25, 0/5, 1, 2, 4 and 8 mg/ml methacholine. Furthermore, bronchoalveolar lavage (BAL) fluid were used to study the eosinophilic inflammation. The increased airway inflammation was found only in the allergen group (p<0.0001). Compared with control group, airway responsiveness were significantly increased in asthmatic rats that received 4 mg/ml (p<0.01) and 8 mg/ml (p<0.0001) methacholine. Respiratory rate, was not significantly different between the two groups. The respiratory volume in ovalbumin group had significant decrease to baseline (p<0.01) and Saline group (p<0.001). The respiratory dynamics showed an increased regularity in asthmatic rats, compared to baseline (p<0.05) and control group (p<0.001). The less complexity of the breathing pattern in asthmatic animals denotes that breathing pattern of asthmatic rats is more regular. This finding may be caused by central mechanisms.