Animal subject approval: Institutional approval was obtained for the use of the animals in this study.
Animals, anesthesia and preparation: Fourteen male Fischer rats eight- to 10-weeks of age and weighing 130 to 330 g (Charles River) were housed in a conventional rat colony at the Toronto General Hospital Animal Centre. Rats were first sedated with xylazine (7 mg/kg intraperitoneally) and anesthetized 15 to 20 mins later with pentobarbital sodium (30 mg/kg intraperitoneally). Orotracheal intubation was performed using a 6 cm polyethylene catheter (PE-240). A saline filled-catheter (PE-160) was placed in the lower third of each animal’s esophagus. The animal was placed on a heating pad, in a right decubitus position. Rectal temperature, monitored using an electronic thermometer, was maintained constant throughout the experiment. Measurement of lung mechanics: The end of the orotracheal tube was connected to a small (250 mL) plastic box (Figure 1). buy ortho tri-cyclen
Figure 1) The experimental setup. The rat is lying in a lateral decubitus position on a heating pad. Orotracheal tube, esophageal catheter and rectal thermistor are placed. The transducers, data acquisition system and aerosol delivery setup are shown. A/D Analogue/digital; ET Endotracheal catheter; lpm Litres per minute; P Pressure; Pbox Box pressure; Pes Esophageal pressure; PTG Pneumotachograph; Ptp Transpulmonary pressure; V Airflow