Is Misplaced Enzyme to Blame for Post-Exercise Fatigue in Chronic Fatigue Syndrome?

Monday December 1, 2008

NEWSBRIEF: Scientists from the Howard Hughes Medical Institute say they've made a discovery that could be significant for treating exercise-related fatigue (called post-exertional malaise) in people with chronic fatigue syndrome (CFS or ME/CFS), some forms of muscular dystrophy and multiple sclerosis.

Researchers say an enzyme called neuronal nitric oxide synthase (nNOS) isn't where it should be, which is in the membrane surrounding your muscle cells. The effect of this missing enzyme is that the blood vessels feeding active muscles don't relax like they should. In animal trials, this causes fatigue after very mild levels of exertion.

Also in those animal trials, a Viagra-like drug helped regulate nitric oxide activity and allowed for much more physical activity. Researchers say, however, that Viagra is too short lasting to be considered a treatment for people with lowered exercise tolerance. Longer-acting drugs in the same class (PDE inhibitors) currently are being used experimental and could be considered for clinical trials.