Nitric oxide metabolite production during exercise in chronic fatigue syndrome: a case-control study.
BACKGROUND
Chronic fatigue syndrome (CFS) is a disabling illness of unknown etiology that is characterized by fatigue associated with a reduced ability to work, lasting for more than 6 months, and accompanied by a specific set of symptoms. The diagnosis remains difficult because of the absence of laboratory tests and is, therefore, made largely on the basis of the symptoms reported by the patient. The aim of this study was to analyze differences in blood nitrate levels in CFS patients and a matched control group after a physical exercise test.


METHODS
Forty-four consecutive female patients with CFS and 25 healthy women performed an exercise test using a cycle ergometer with monitoring of cardiopulmonary response. Blood samples were obtained for biochemical analyses of glucose, lactate, and nitrates at the beginning (under resting conditions) and after the maximal and supramaximal tests.


RESULTS
Plasma nitrates differed between the groups, with higher values in the CFS group (F = 6.93, p = 0.003). Nitrate concentration increased in relation to workload and reached higher values in the CFS group, the maximum difference with respect to the control group being 295% (t = 4.88, p < 0.001).


CONCLUSIONS
The main result of the present study is that nitric oxide (NO) metabolites (nitrates) showed a much higher increase after a maximal physical test in CFS patients than in a group of matched subjects. This combination (exercise plus NO response evaluation) may be useful in the assessment of CFS.
Suárez
Andrea
A
Department of Physiological Sciences II, Medical School, University of Barcelona, L'Hospitalet, Barcelona, Spain.
Guillamó
Elisabet
E
Roig
Teresa
T
Blázquez
Alicia
A
Alegre
José
J
Bermúdez
Jordi
J
Ventura
José Luis
JL
García-Quintana
Ana María
AM
Comella
Agustí
A
Segura
Ramon
R
Javierre
Casimiro
C
D000704:Analysis of Variance; D016022:Case-Control Studies; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D015673:Fatigue Syndrome, Chronic / Q000097:blood / Q000378:metabolism*; D005260:Female; D006801:Humans; D009569:Nitric Oxide / Q000096:biosynthesis* / Q000097:blood
D009569:Nitric Oxide