title: Dietary docosahexaenoic acid supplementation reduces SERCA Ca2+ transport efficiency in rat skeletal muscle.
abstract: Docosahexaenoic acid (DHA) can reduce the efficiency and increase the energy consumption of Na(+)/K(+)-ATPase pump and mitochondrial electron transport chain by promoting Na(+) and H(+) membrane permeability, respectively. In skeletal muscle, the sarco(endo) plasmic reticulum Ca(2+)-ATPase (SERCA) pumps are major contributors to resting metabolic rate. Whether DHA can affect SERCA efficiency remains unknown. Here, we examined the hypothesis that dietary supplementation with DHA would reduce Ca(2+) transport efficiency of the SERCA pumps in skeletal muscle. Total lipids were extracted from enriched sarcoplasmic reticulum (SR) membranes that were isolated from red vastus lateralis skeletal muscles of rats that were either fed a standard chow diet supplemented with soybean oil or supplemented with DHA for 8 weeks. The fatty acid composition of total SR membrane lipids and the major phospholipid species were determined using electrospray ionization mass spectrometry (ESI-MS). After 8 weeks of DHA supplementation, total SR DHA content was significantly elevated (control, 4.1 ± 1.0% vs. DHA, 9.9 ± 1.7%; weight percent of total fatty acids) while total arachidonic acid was reduced (control, 13.5 ± 0.4% vs. DHA-fed, 9.4 ± 0.2). Similar changes in these fatty acids were observed in phosphatidylcholine, phosphatidylethanolamine, and phosphatidylinositol, altogether indicating successful incorporation of DHA into the SR membranes post-diet. As hypothesized, DHA supplementation reduced SERCA Ca(2+) transport efficiency (control, 0.018 ± 0.0002 vs. DHA-fed, 0.014 ± 0.0009) possibly through enhanced SR Ca(2+) permeability (ionophore ratio: control, 2.8 ± 0.2 vs. DHA-fed, 2.2 ± 0.3). Collectively, our results suggest that DHA may promote skeletal muscle-based metabolism and thermogenesis through its influence on SERCA.
authors.affiliation: Department of Kinesiology, University of Waterloo, Waterloo, Ontario, N2L 3G1, Canada.
authors.forename: Val Andrew
authors.initials: VA
authors.lastname: Fajardo
authors.affiliation: Department of Kinesiology, University of Waterloo, Waterloo, Ontario, N2L 3G1, Canada.
authors.forename: Eric
authors.initials: E
authors.lastname: Bombardier
authors.affiliation: Department of Kinesiology, University of Waterloo, Waterloo, Ontario, N2L 3G1, Canada.
authors.forename: Thomas
authors.initials: T
authors.lastname: Irvine
authors.affiliation: Department of Kinesiology, University of Waterloo, Waterloo, Ontario, N2L 3G1, Canada.
authors.forename: Adam H
authors.initials: AH
authors.lastname: Metherel
authors.affiliation: Department of Kinesiology, University of Waterloo, Waterloo, Ontario, N2L 3G1, Canada.
authors.forename: Ken D
authors.initials: KD
authors.lastname: Stark
authors.affiliation: Health, Leisure, and Human Performance Research Institute, Faculty of Kinesiology and Recreation Management, University of Manitoba, Winnipeg, MB R3T 2N2 Canada; Institute of Cardiovascular Sciences, St. Boniface Hospital Research Centre, 351 Tache Avenue, Winnipeg MB R2H 2A6, Canada.
authors.forename: Todd
authors.initials: T
authors.lastname: Duhamel
authors.affiliation: Department of Kinesiology, University of Waterloo, Waterloo, Ontario, N2L 3G1, Canada.
authors.forename: James W E
authors.initials: JW
authors.lastname: Rush
authors.affiliation: Department of Kinesiology, University of Waterloo, Waterloo, Ontario, N2L 3G1, Canada.
authors.forename: Howard J
authors.initials: HJ
authors.lastname: Green
authors.affiliation: Department of Kinesiology, University of Waterloo, Waterloo, Ontario, N2L 3G1, Canada. Electronic address: rtupling@uwaterloo.ca.
authors.forename: A Russell
authors.initials: AR
authors.lastname: Tupling
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology*; D019587:Dietary Supplements; D004281:Docosahexaenoic Acids / Q000008:administration & dosage*; D006801:Humans; D015640:Ion Channel Gating / Q000187:drug effects / Q000502:physiology; D008297:Male; D018482:Muscle, Skeletal / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D011921:Rats, Inbred WKY; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases / Q000187:drug effects / Q000378:metabolism*
chemical_list: D004281:Docosahexaenoic Acids; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases; D002118:Calcium
keywords: Ca(2+) transport efficiency; Docosahexaenoic acid; SERCA; Sarcoplasmic reticulum