Tag: muscle excitability

Altered muscle membrane potential and redox status differentiates two subgroups of patients with chronic fatigue syndrome

Abstract:

BACKGROUND: In myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), altered membrane excitability often occurs in exercising muscles demonstrating muscle dysfunction regardless of any psychiatric disorder. Increased oxidative stress is also present in many ME/CFS patients and could affect the membrane excitability of resting muscles.

METHODS: Seventy-two patients were examined at rest, during an incremental cycling exercise and during a 10-min post-exercise recovery period. All patients had at least four criteria leading to a diagnosis of ME/CFS. To explore muscle membrane excitability, M-waves were recorded during exercise (rectus femoris (RF) muscle) and at rest (flexor digitorum longus (FDL) muscle). Two plasma markers of oxidative stress (thiobarbituric acid reactive substance (TBARS) and oxidation-reduction potential (ORP)) were measured. Plasma potassium (K+) concentration was also measured at rest and at the end of exercise to explore K+ outflow.

RESULTS: Thirty-nine patients had marked M-wave alterations in both the RF and FDL muscles during and after exercise while the resting values of plasma TBARS and ORP were increased and exercise-induced K+ outflow was decreased. In contrast, 33 other patients with a diagnosis of ME/CFS had no M-wave alterations and had lower baseline levels of TBARS and ORP. M-wave changes were inversely proportional to TBARS and ORP levels.

CONCLUSIONS: Resting muscles of ME/CFS patients have altered muscle membrane excitability. However, our data reveal heterogeneity in some major biomarkers in ME/CFS patients. Measurement of ORP may help to improve the diagnosis of ME/CFS.

Trial registration Ethics Committee “Ouest II” of Angers (May 17, 2019) RCB ID: number 2019-A00611-56.

Source: Jammes Y, Adjriou N, Kipson N, Criado C, Charpin C, Rebaudet S, Stavris C, Guieu R, Fenouillet E, Retornaz F. Altered muscle membrane potential and redox status differentiates two subgroups of patients with chronic fatigue syndrome. J Transl Med. 2020 Apr 19;18(1):173. doi: 10.1186/s12967-020-02341-9. https://www.ncbi.nlm.nih.gov/pubmed/32306967

Association of biomarkers with health-related quality of life and history of stressors in myalgic encephalomyelitis/chronic fatigue syndrome patients

Abstract:

BACKGROUND: Myalgic encephalomyelitis chronic fatigue syndrome (ME/CFS) is a common debilitating disorder associated with an intense fatigue, a reduced physical activity, and an impaired quality of life. There are no established biological markerof the syndrome. The etiology is unknown and its pathogenesis appears to be multifactorial. Various stressors, including intense physical activity, severe infection, and emotional stress are reported in the medical history of ME/CFS patients which raises the question whether any physiological and biological abnormalities usually found in these patients could be indicative of the etiology and/or the quality-of-life impairment.

METHODS: Thirty-six patients and 11 age-matched healthy controls were recruited. The following variables that appear to address common symptoms of ME/CFS were studied here: (1) muscle fatigue during exercise has been investigated by monitoring the compound muscle action potential (M-wave); (2) the excessive oxidative stress response to exercise was measured via two plasma markers (thiobarbituric acid reactive substances: TBARS; reduced ascorbic-acid: RAA); (3) a potential inflammatory component was addressed via expression of CD26 on peripheral blood mononuclear cells; (4) quality-of-life impairment was assessed using the London Handicap Scale (LHS) and the Medical Outcome Study Short Form-36 (SF-36). The medical history of each patient, including the presence of stressors such as intense sports practice, severe acute infection and/or severe emotional stress was documented.

RESULTS: We observed that: (1) there were striking differences between cases and controls with regard to three biological variables: post-exercise M-wave, TBARS variations and CD26-expression at rest; (2) each of these three variables correlated with the other two; (3) abnormalities in the biomarkers associated with health-related quality of life: the LHS score was negatively correlated with the exercise-induced TBARS increase and positively correlated with CD26-expression while the pain component of SF-36 was negatively correlated with CD26-expression; (4) the TBARS increase and the M-wave decrease were the highest, and the CD26-expression level the lowest in patients who had been submitted to infectious stressors.

CONCLUSION: In ME/CFS patients, severe alterations of the muscle excitability, the redox status, as well as the CD26-expression level are correlated with a marked impairment of the quality-of-life. They are particularly significant when infectious stressors are reported in the medical history.

 

Source: Fenouillet E, Vigouroux A, Steinberg JG, Chagvardieff A, Retornaz F, Guieu R, Jammes Y. Association of biomarkers with health-related quality of life and history of stressors in myalgic encephalomyelitis/chronic fatigue syndrome patients. J Transl Med. 2016 Aug 31;14:251. doi: 10.1186/s12967-016-1010-x. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5006431/ (Full article)

 

Chronic fatigue syndrome: assessment of increased oxidative stress and altered muscle excitability in response to incremental exercise

Abstract:

OBJECTIVES: Because the muscle response to incremental exercise is not well documented in patients suffering from chronic fatigue syndrome(CFS), we combined electrophysiological (compound-evoked muscle action potential, M wave), and biochemical (lactic acid production, oxidative stress) measurements to assess any muscle dysfunction in response to a routine cycling exercise.

DESIGN: This case-control study compared 15 CFS patients to a gender-, age- and weight-matched control group (n=11) of healthy subjects.

INTERVENTIONS: All subjects performed an incremental cycling exercise continued until exhaustion.

MAIN OUTCOME MEASURES: We measured the oxygen uptake (VO2), heart rate (HR), systemic blood pressure, percutaneous O2 saturation (SpO2), M-wave recording from vastus lateralis, and venous blood sampling allowing measurements of pH (pHv), PO2 (PvO2), lactic acid (LA), and three markers of the oxidative stress (thiobarbituric acid-reactive substances, TBARS, reduced glutathione, GSH, and ascorbic acid, RAA).

RESULTS: Compared with control, in CFS patients (i) the slope of VO2 versus work load relationship did not differ from control subjects and there was a tendency for an accentuated PvO2 fall at the same exercise intensity, indicating an increased oxygen uptake by the exercising muscles; (ii) the HR and blood pressure responses to exercise did not vary; (iii) the anaerobic pathways were not accentuated; (iv) the exercise-induced oxidative stress was enhanced with early changes in TBARS and RAA and enhanced maximal RAA consumption; and (v) the M-wave duration markedly increased during the recovery period.

CONCLUSIONS: The response of CFS patients to incremental exercise associates a lengthened and accentuated oxidative stress together with marked alterations of the muscle membrane excitability. These two objective signs of muscle dysfunction are sufficient to explain muscle pain and postexertional malaise reported by our patients.

 

Source: Jammes Y, Steinberg JG, Mambrini O, Brégeon F, Delliaux S. Chronic fatigue syndrome: assessment of increased oxidative stress and altered muscle excitability in response to incremental exercise. J Intern Med. 2005 Mar;257(3):299-310. http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2796.2005.01452.x/full (Full article)