title: L-carnitine combined with minimal electrical stimulation promotes type transformation of canine latissimus dorsi.
abstract: In the first part of this study, in four dogs the left latissimus dorsi was equipped to perform in vivo contraction measurements and the right latissimus dorsi served as control. After a control period, the dogs received L-carnitine intravenously for 8 wk. We found that carnitine caused the percentage of type I fibers to increase from 30 to 55% in the left latissimus dorsi but no change in the right latissimus dorsi. In the left latissimus dorsi, the contraction speed (percentage ripple) decreased from 75 to 30% and cytochrome-c oxidase activity increased 1.6-fold. No changes occurred in the right latissimus dorsi. To verify these observations, we performed a second study with placebo control for 8 wk, and only the left latissimus dorsi was subjected to weekly electrical stimulation. In the carnitine-treated dogs, the stimulated muscle showed an increase in the percentage of type I fibers from 16 to 35% and the ripple decreased from 92 to 77%. These measures did not change in the placebo-treated dogs. We concluded that weekly short-term stimulation does not lead to a change in fiber type; however, carnitine combined with minimal stimulation of the muscle leads to a significant shift in muscle fiber type composition toward a muscle with an increased content of type I fibers.
authors.affiliation: Department of Physiology, Cardiovascular Research Institute Maastricht, University of Limburg, The Netherlands.
authors.forename: M L
authors.initials: ML
authors.lastname: Dubelaar
authors.forename: J F
authors.initials: JF
authors.lastname: Glatz
authors.forename: Y F
authors.initials: YF
authors.lastname: De Jong
authors.forename: F H
authors.initials: FH
authors.lastname: Van der Veen
authors.forename: W C
authors.initials: WC
authors.lastname: Hülsmann
mesh_terms: D000818:Animals; D001823:Body Composition / Q000502:physiology; D002331:Carnitine / Q000378:metabolism / Q000494:pharmacology*; D004285:Dogs; D004558:Electric Stimulation; D004567:Electrodes, Implanted; D003576:Electron Transport Complex IV / Q000378:metabolism; D005221:Fatigue / Q000503:physiopathology; D007150:Immunohistochemistry; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects / Q000502:physiology; D009132:Muscles / Q000166:cytology / Q000378:metabolism / Q000502:physiology*; D010084:Oxidation-Reduction; D010168:Palmitates / Q000378:metabolism
chemical_list: D010168:Palmitates; D003576:Electron Transport Complex IV; D002331:Carnitine