Whole body plethysmography (WBP) is used to quantify pulmonary function in conscious, unrestrained mice. We determined currently whether time of day and environmental lighting influence day-to-day reproducibility of pulmonary function, and quantifed the necessary habituation time in the WBP chamber. Two-month-old male C57BL6 and mdx mice (n = 8/group, reverse light cycle), were examined on consecutive days using a calibrated WBP chamber and manufacturer software was used to calculate respiratory measures. Respiratory data stabilized between 5-10 min for all variables. Mice exhibited time of day respiratory differences, performing more forceful and less frequent breaths midday (11:45 a.m. and 3:00 p.m.) compared to 7:30 a.m. WBP performed in darkened conditions elicited more forceful breathing than lit conditions. Day-to-day reproducibility during controlled conditions ranged from r(2) = 0.58 to 0.62 for the functional measures. Findings indicate reproducible respiratory data are obtainable following a 15-min chamber habituation and standardization of time of day and room lighting.
Keywords: Mdx; Respiration; Whole body plethysmography.