title: Excitation-contraction coupling properties in women with work-related myalgia: a preliminary study.
abstract: We investigated the potential role of selected excitation-contraction coupling processes in females with work-related myalgia (WRM) by comparing WRM with healthy controls (CON) using tissue from extensor carpi radialis brevis (ECRB) and trapezius (TRAP) muscles. For the ECRB, age (mean ± SE) was 29.6 ± 3.5 years for CON (n = 9) and 39.2 ± 2.8 years for WRM (n = 13), while for the TRAP, the values were 26.0 ± 2.1 years for CON (n = 7) and 44.6 ± 2.9 years for WRM (n = 11). For the sarcoplasmic reticulum (SR) of the ECRB, WRM displayed concentrations (nmol·(mg protein)(-1)·min(-1)) that were lower (P < 0.05) for Total (202 ± 4.4 vs 178 ± 7.1), Basal (34 ± 1.6 vs 30.1 ± 1.3), and maximal Ca(2+)-ATPase activity (Vmax, 168 ± 4.9 vs 149 ± 6.3), and Ca(2+)-uptake (5.06 ± 0.31 vs 4.13 ± 0.29), but not SERCA1a and SERCA2a isoforms, by comparison with CON. When age was incorporated as a co-variant, Total, Basal, and Ca(2+)-uptake remained different from CON (P < 0.05), but not Vmax (P = 0.13). For TRAP, none of the ATPase properties differed between groups (P > 0.05) either before or following adjustment for age. No differences (P > 0.05) were observed between the groups for Ca(2+)-release in the SR for either TRAP or ECRB. Similarly, no deficiencies, regardless of muscle, were noted for either the Na(+)-K(+)-ATPase content or the α and β subunit isoform distribution in WRM. This preliminary study provides a basis for further research, with expanded numbers, investigating the hypothesis that abnormalities in SR Ca(2+)-regulation are involved in the cellular etiology of WRM.
authors.affiliation: a Department of Kinesiology, University of Waterloo, Waterloo, ON N2L 3G1, Canada.
authors.forename: Howard J
authors.initials: HJ
authors.lastname: Green
authors.forename: Don
authors.initials: D
authors.lastname: Ranney
authors.forename: Margaret
authors.initials: M
authors.lastname: Burnett
authors.forename: Patti
authors.initials: P
authors.lastname: Galvin
authors.forename: Natasha
authors.initials: N
authors.lastname: Kyle
authors.forename: David
authors.initials: D
authors.lastname: Lounsbury
authors.forename: Jing
authors.initials: J
authors.lastname: Ouyang
authors.forename: Ian C
authors.initials: IC
authors.lastname: Smith
authors.forename: Riley
authors.initials: R
authors.lastname: Stewart
authors.forename: Heather
authors.initials: H
authors.lastname: Tick
authors.forename: A Russell
authors.initials: AR
authors.lastname: Tupling
mesh_terms: D000328:Adult; D002118:Calcium / Q000378:metabolism*; D016022:Case-Control Studies; D056966:Excitation Contraction Coupling; D005260:Female; D005356:Fibromyalgia / Q000378:metabolism; D006801:Humans; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000378:metabolism; D063806:Myalgia / Q000378:metabolism*; D009784:Occupational Diseases / Q000378:metabolism*; D012519:Sarcoplasmic Reticulum / Q000378:metabolism*; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases / Q000378:metabolism*; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism; D055815:Young Adult
chemical_list: D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases; C506943:ATP2A1 protein, human; C506946:ATP2A2 protein, human; D000254:Sodium-Potassium-Exchanging ATPase; D002118:Calcium
keywords: calcium regulation; couplage excitation–contraction; excitation–contraction coupling; extensor carpi radialis brevis; muscle court extenseur radial du carpe; myalgia; myalgie; régulation du calcium; réticulum sarcoplasmique; sarcoplasmic reticulum; trapezius; trapèze; travail; work