Differential Consequences of Unilateral Nasal Air-Puff Stimulation on Breathing Pattern and Respiratory System Mechanics in Tracheotomized Rats

Objective(s): Reflexes that rose from mechanoreceptors in nasal cavities have extensive neuro-regulatory effects on respiratory system. Because of side specific geometry and dual innervations of the nasal mucosa, we investigated the consequences of unilateral nasal stimulations on respiratory mechanics and breathing patterns. Materials and Methods: Unilateral nasal air-puff stimulation (30 min) in the presence of propranolol (25 mg/kg) and atropine (5 mg/kg) were applied on tracheotomized spontaneously breathing rats. Breathing rate and pattern monitored. Peak inspiratory pressure (PIP) and flow (PIF) were exploited for calculation of resistance, dynamic compliance (C(dyn)), and estimation of respiratory system impedance (Z(rs)). Results: During right-side stimulation, in propranolol (P<0.05) and atropine groups (P<0.01) PIP significantly decreased in comparison to the control group. Alternatively, it significantly increased in left-side and propranolol-left groups (P<0.05) than control group. Mean C(dyn) following left-side stimulation and propranolol, revealed significant decrements (P<0.05) than control group. In the case of atropine-right and atropine-left groups, mean C(dyn) had significantly decreased in comparison with atropine alone (P<0.05). Airway resistance (R) did not reveal significant difference during nasal stimulations whereas least square approximation revealed a significant side-specific frequency dependent deviation of imaginary part of impedance (X). An inverse correlation was determined for C(dyn) versus frequency following right side (R=-0.76) and left side (R=-0.53) stimulations. Conclusion: For the reason that lower airways mechanics changed in a way independent from smooth muscle, it may be concluded from our data that unilateral nasal stimulations exert their different controls through higher regulatory centers.