Fig. 3

Diaphragm and respiration assessment in R-DMDdel52 rats. a, b Recording trace of respiratory flow of WT (a) and R-DMDdel52 rats (b) aged 6 months under baseline conditions. Negative flow peaks indicate depression in the box, i.e. the inspiration step for the animal, while the positive ones reflect the expiration. c–f exhalation time (c), tidal volume (d), respiratory rate (e) and minute ventilation (f) measured by whole body plethysmography in R-DMDdel52 and WT rats aged 6 months. g, h Hematoxylin and eosin (upper panels) and Picro Sirius red (lower panels) staining of diaphragm of 3-week-old (g) and 3-month-old (h) WT and R-DMDdel52 rats (scale bar 50 μm). i Percentage of Sirius red area in diaphragm of 3-week-old and 3-month-old WT and DMDdel52 rats. j, k Hematoxylin and eosin (upper panels) and Picro Sirius red (lower panels) staining of diaphragm at 6 months (j) and 12 months (k) of age of both WT and R-DMDdel52 rats (scale bar 50 μm). l Percentage of Sirius red area in diaphragm of WT and DMDdel52 rats aged 6 and 12 months