A novel protocol for assessing exercise performance and dystropathophysiology in the mdx mouse.
BACKGROUND
Dystrophinopathy in the young mdx mouse model of Duchenne muscular dystrophy is comparatively mild, requires induction, and is rarely assessed with tests of systemic muscle function in whole animals.


METHODS
A modified TREAT-NMD induction protocol was used to evaluate respiratory and exercise performance, starting and ending with maximum oxygen consumption (VO2max ) tests.


RESULTS
The initial and/or final VO2max , time to exhaustion, speed at exhaustion, and total expended calories were significantly lower in mdx mice. Episodic VO2 and VCO2 fluctuations occurred during training and resulted in dissociated patterns of VO2 and respiratory exchange ratio (RER). These fluctuations further resulted in significantly greater VO2 coefficient of variation and RER values and lower minimal VO2 values.


CONCLUSIONS
Quantifying respiratory performance during exercise is a potentially useful means for studying pathophysiology in mdx mice, as it assesses intact animals over time, is more sensitive than some histological markers, and assesses systemic muscle function.
College of Veterinary Medicine, Washington Center for Muscle Biology, Washington State University, Pullman, Washington, USA.
Andrew B
AB
Rocco
Jewel C
JC
Levalley
Jennifer A
JA
Eldridge
Susan A
SA
Marsh
Buel D
BD
Rodgers
D000818:Animals; D003094:Collagen / Q000378:metabolism; D003430:Cross-Sectional Studies; D004195:Disease Models, Animal; D004734:Energy Metabolism / Q000502:physiology; D005080:Exercise Test; D051379:Mice; D008810:Mice, Inbred C57BL; D018101:Mice, Inbred mdx; D018482:Muscle, Skeletal / Q000378:metabolism / Q000473:pathology; D020388:Muscular Dystrophy, Duchenne / Q000150:complications* / Q000209:etiology; D010101:Oxygen Consumption; D010805:Physical Conditioning, Animal / Q000009:adverse effects / Q000502:physiology*; D012129:Respiratory Function Tests; D012131:Respiratory Insufficiency / Q000209:etiology*; D013997:Time Factors
D003094:Collagen
Duchenne muscular dystrophy; VO2; exercise; mdx; respiratory performance