Diagram of the plethysmograph used for pulmonary function testing of anesthetized, orotracheally intubated mice. A thermostat-controlled water basin (37°C) built in the plethysmograph chamber ensured a body temperature of 34–35°C as measured by rectal thermometer. Defined aerosol concentrations of methacholine, as measured by an aerosol photometer, were delivered into the airways via the orotracheal tube. For calculation of pulmonary resistance (RL), transpulmonary pressure (PTP) was recorded via an esophageal tube, and tidal flow was determined by a pneumotachograph attached directly to the orotracheal tube. PT, pressure transducer. Taken from  with permission.