The mdx mouse is a model of
Duchenne muscular dystrophy. The present invention describes that mdx mice exhibited clinically relevant cardiac phenotypes. A non-invasive method of recording electrocardiograms (ECGs) was used to a study mdx mice (n=15) and control mice (n=15). The mdx mice had significant
tachycardia, consistent with observations in patients with
muscular dystrophy. Heart-rate was nearly 15% faster in mdx mice than control mice (P<0.01). ECGs revealed significant shortening of the rate-corrected
QT interval duration (QTc) in mdx mice compared to control mice (P<0.05).
PR interval duration were shorter at baseline in mdx compared to control mice (P<0.05). The
muscarinic antagonist atropine significantly increased heart-rate and decreased
PR interval duration in C57 mice. Paradoxically,
atropine significantly decreased heart-rate and increased
PR interval duration in all mdx mice. Pharmacological autonomic
blockade and
baroreflex sensitivity testing demonstrated an imbalance in
autonomic nervous system modulation of heart-rate, with decreased parasympathetic activity and increased
sympathetic activity in mdx mice. These electrocardiographic findings in
dystrophin-deficient mice provide new bases for diagnosing, understanding, and treating patients with
Duchenne muscular dystrophy.