Histology of cardiac muscle and hydroxyproline content.

<p>(A) Photomicrograph of cardiac muscle (H&E stained, 10x) from 6-mo and 18-mo old mdx mice exposed to room air (RA) and episodic hypoxia (EH). Note higher amount of fibrosis and interstitial space in 18-mo old <i>mdx</i> mice as compared to 6-mo old <i>mdx</i> mice. EH exposed mice heart showed higher amount of fibrosis and interstitial space as compared to RA controls in 18-mo old <i>mdx</i> mice. (B) Cardiac hydroxyproline levels (μg/mg wet tissue weight) measured by biochemical analysis. a, significant difference (p<0.05) 6-mo vs 18-mo old RA <i>mdx</i> mice; b, significant difference (p<0.05) RA vs EH group of same age. (C) Cardiomyocyte Size, Effect of aging and episodic hypoxia on cardiomyocyte (LV free wall and septal) size in mdx mice.