FIG. 5.

Ozone-induced changes in lung minute volume and PenH, an index of labored breathing, in SHAM, DEMED, and ADREX rats. The plethysmography was performed the morning prior to first ozone exposure (1-D Morning), immediately following first ozone exposure (1-D Afternoon), and prior to the start of second exposure (2-D Morning). A, Minute volume was calculated based on breathing frequency and tidal volume and the values were normalized to body weight. B, PenH values were computed from all ventilatory parameters measured during plethysmography. Values indicate mean ± SEM (n = 4–6/group). *Indicates ozone effect when compared with matching air group at a given time point P ≤ .05. †Indicates surgery effect within matching exposure group at a given time point P ≤ .5.