title: High-intensity interval and endurance training are associated with divergent skeletal muscle adaptations in a rodent model of hypertension.
abstract: Skeletal muscle is extremely adaptable to a variety of metabolic challenges, as both traditional moderate-intensity endurance (ET) and high-intensity interval training (HIIT) increases oxidative potential in a coordinated manner. Although these responses have been clearly demonstrated in healthy individuals, it remains to be determined whether both produce similar responses in the context of hypertension, one of the most prevalent and costly diseases worldwide. Therefore, in the current study, we used the Dahl sodium-sensitive rat, a model of hypertension, to determine the molecular responses to 4 wk of either ET or HIIT in the red (RG) and white gastrocnemius (WG) muscles. In the RG, both ET and HIIT increased the content of electron transport chain proteins and increased succinate dehydrogenase (SDH) content in type I fibers. Although both intensities of exercise shifted fiber type in RG (increased IIA, decreased IIX), only HIIT was associated with a reduction in endothelial nitric oxide synthase and an increase in HIF-1α proteins. In the WG, both ET and HIIT increased markers of the electron transport chain; however, HIIT decreased SDH content in a fiber-specific manner. ET increased type IIA, decreased IIB fibers, and increased capillarization, while, in contrast, HIIT increased the percentage of IIB fibers, decreased capillary-to-fiber ratios, decreased endothelial nitric oxide synthase, and increased hypoxia inducible factor-1α (HIF-1α) protein. Altogether, these data show that unlike in healthy animals, ET and HIIT have divergent effects in the skeletal muscle of hypertensive rats. This suggests ET may be optimal at improving the oxidative capacity of skeletal muscle in animals with hypertension.
authors: Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada; and thollowa@uoguelph.ca.
authors: Tanya M
authors: TM
authors: Holloway
authors: Department of Kinesiology, University of Waterloo, Waterloo, Ontario, Canada.
authors: Darin
authors: D
authors: Bloemberg
authors: Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada; and.
authors: Mayne L
authors: ML
authors: da Silva
authors: Department of Kinesiology, University of Waterloo, Waterloo, Ontario, Canada.
authors: Joe
authors: J
authors: Quadrilatero
authors: Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada; and.
authors: Lawrence L
authors: LL
authors: Spriet
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D001794:Blood Pressure; D002196:Capillaries / Q000378:metabolism / Q000503:physiopathology; D004195:Disease Models, Animal; D045222:Electron Transport Chain Complex Proteins / Q000378:metabolism; D006973:Hypertension / Q000209:etiology / Q000378:metabolism / Q000503:physiopathology*; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000378:metabolism; D008297:Male; D008931:Mitochondria, Muscle / Q000378:metabolism; D009119:Muscle Contraction; D018656:Muscle Fibers, Fast-Twitch / Q000378:metabolism; D018657:Muscle Fibers, Slow-Twitch / Q000378:metabolism; D018482:Muscle, Skeletal / Q000098:blood supply* / Q000378:metabolism / Q000503:physiopathology*; D018919:Neovascularization, Physiologic; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism; D010807:Physical Endurance; D005082:Physical Exertion; D020303:Rats, Inbred Dahl; D017673:Sodium Chloride, Dietary; D013385:Succinate Dehydrogenase / Q000378:metabolism; D013997:Time Factors
chemical_list: D045222:Electron Transport Chain Complex Proteins; C497444:Hif1a protein, rat; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D017673:Sodium Chloride, Dietary; D052250:Nitric Oxide Synthase Type III; C496316:Nos3 protein, rat; D013385:Succinate Dehydrogenase
keywords: Dahl sodium-sensitive; capillary density; fiber type; heart failure; high-intensity interval training; hypertension; mitochondrial content; skeletal muscle