New research has revealed that a misplaced enzyme may be the cause of post-exertional malaise in ME/CFS and MS. A new Viagra-like drug may provide benefits to disorders with exaggerated exercise-induced fatigue response.
Howard Hughes Medical Institute scientists have uncovered a molecular explanation for the profound fatigue brought on by mild exercise in some people with muscular dystrophy.
In studies with genetically engineered mice that showed this form of fatigue after mild exercise, the researchers found that an enzyme called neuronal nitric oxide synthase (nNOS) is not present at its normal location in the membrane surrounding muscle cells. This means the blood vessels that supply active muscles do not relax normally and the animals experience fatigue after very mild exercise.
Researchers found that once they discovered the cause, patients post-exertional malaise/fatigue could be relieved with medication.
When the scientists administered Viagra-like drugs to the mice with muscular dystrophy, they noticed an increase in their ability to move, as well as a dramatic increase in their activity after mild exercise. The treated mice were two to four times more active than untreated mice with muscular dystrophy. Prior to treatment, the same mice would become virtually inert after a short burst of low-intensity activity.
The researchers say they have traced the cause of the post-exertional malaise to a disruption of nitric oxide signaling in muscle cells to blood vessels.
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