title: Metabolic and functional effects of beta-hydroxy-beta-methylbutyrate (HMB) supplementation in skeletal muscle.
abstract: Beta-hydroxy-beta-methylbutyrate (HMB) is a metabolite derived from leucine. The anti-catabolic effect of HMB is well documented but its effect upon skeletal muscle strength and fatigue is still uncertain. In the present study, male Wistar rats were supplemented with HMB (320 mg/kg per day) for 4 weeks. Placebo group received saline solution only. Muscle strength (twitch and tetanic force) and resistance to acute muscle fatigue of the gastrocnemius muscle were evaluated by direct electrical stimulation of the sciatic nerve. The content of ATP and glycogen in red and white portions of gastrocnemius muscle were also evaluated. The effect of HMB on citrate synthase (CS) activity was also investigated. Muscle tetanic force was increased by HMB supplementation. No change was observed in time to peak of contraction and relaxation time. Resistance to acute muscle fatigue during intense contractile activity was also improved after HMB supplementation. Glycogen content was increased in both white (by fivefold) and red (by fourfold) portions of gastrocnemius muscle. HMB supplementation also increased the ATP content in red (by twofold) and white (1.2-fold) portions of gastrocnemius muscle. CS activity was increased by twofold in red portion of gastrocnemius muscle. These results support the proposition that HMB supplementation have marked change in oxidative metabolism improving muscle strength generation and performance during intense contractions.
authors.affiliation: Department of Physiology and Biophysics, room 105, Institute of Biomedical Science, University of São Paulo, Av. Prof. Lineu Prestes, 1524, Prédio Biomédicas I, Cidade Universitária, Butantã, São Paulo, SP, CEP:05508-900, Brazil. chjpinheiro@gmail.com
authors.forename: Carlos Hermano da Justa
authors.initials: CH
authors.lastname: Pinheiro
authors.forename: Frederico
authors.initials: F
authors.lastname: Gerlinger-Romero
authors.forename: Lucas
authors.initials: L
authors.lastname: Guimarães-Ferreira
authors.forename: Alcione Lescano
authors.initials: AL
authors.lastname: de Souza
authors.forename: Kaio Fernando
authors.initials: KF
authors.lastname: Vitzel
authors.forename: Renato Tadeu
authors.initials: RT
authors.lastname: Nachbar
authors.forename: Maria Tereza
authors.initials: MT
authors.lastname: Nunes
authors.forename: Rui
authors.initials: R
authors.lastname: Curi
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism*; D000284:Administration, Oral; D000818:Animals; D019587:Dietary Supplements; D006003:Glycogen / Q000378:metabolism*; D008297:Male; D008657:Metabolic Clearance Rate / Q000187:drug effects; D018763:Muscle Fatigue / Q000187:drug effects / Q000502:physiology*; D053580:Muscle Strength / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D017208:Rats, Wistar; D014631:Valerates / Q000008:administration & dosage*
chemical_list: D014631:Valerates; C004961:beta-hydroxyisovaleric acid; D000255:Adenosine Triphosphate; D006003:Glycogen
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