Emka software

Nasal chemosensory nerve stimulation results in the sensory irritant response, characterized by a prolonged braking (slowing or cessation of flow) at the onset of each expiration [9 (link),10 (link)]. As in our previous study, breathing patterns were monitored continuously during the pre-exposure acclimatization period and exposure period using EMKA software (EMKA Technologies, Inc., Falls Church, VA). This software provided measures of breathing frequency, tidal volume, duration of braking during early expiration, peak inspiratory and peak expiratory flow. Data collected from each breath were averaged to provide running 1 minute averages. Irritant exposure caused a typical prolonged braking at the start of each expiration. The duration of this braking period was quantified as the duration required to achieve 25% of the peak expiratory flow rate for each breath [15 (link)]. Data are presented either as a time course (running 1 min averages) or the average response over the entire exposure.

Ventilation was measured in conscious freely moving rats by whole-body plethysmography after 14 and 44 weeks of diet (before surgery) and 9 weeks after surgery, as previously described by Sacramento et al. (2018) (link). The system (emka Technologies, Paris, France) consisted of 5-L methacrylate chambers continuously fluxed (2 L/min) with gases. Tidal volume (VT; ml), respiratory frequency (f; breaths/min; bpm), the product of these two variables, and minute ventilation (VE; ml/min/Kg) were monitored. Each rat was placed in the plethysmography chamber and allowed to breathe room air for 20 min until they adapted to the chamber environment and acquired a standard resting behavior. The protocol consisted of subjecting the animals to 30 min acclimatization followed by 10 min of normoxia (20% O₂ balanced N₂), 10 min of hypoxia (10% O₂ balanced N₂), 10 min of normoxia, 10 min of hypercapnia (20% O₂ + 5% CO₂ balanced N₂), and finally to 10 min of normoxia. A high-gain differential pressure transducer allows measuring the pressure change within the chamber reflecting tidal volume (VT). False pressure fluctuations due to rat movements were rejected. Pressure signals were fed to a computer for visualization and storage for later analysis with EMKA software (emka Technologies, Paris, France).