Zuccarelli 2021 J Physiol

Zuccarelli L, Baldassarre G, Magnesa B, Degano C, Comelli M, Gasparini M, Manferdelli G, Marzorati M, Mavelli I, Pilotto A, Porcelli S, Rasica L, Šimunič B, Pišot R, Narici M, Grassi B (2021) Peripheral impairments of oxidative metabolism after a 10-day bed rest are upstream of mitochondrial respiration. J Physiol [Epub ahead of print].

» PMID: 34505290 Open Access

Zuccarelli L, Baldassarre G, Magnesa B, Degano C, Comelli M, Gasparini M, Manferdelli G, Marzorati M, Mavelli I, Pilotto A, Porcelli S, Rasica L, Šimunič B, Pišot R, Narici M, Grassi B (2021) J Physiol

Abstract: In order to identify peripheral biomarkers of impaired oxidative metabolism during exercise following a 10-day bed rest (BR), 10 males performed an incremental exercise (to determine peak pulmonary V̇O₂[V̇O₂p]) and moderate-intensity exercises, before (PRE) and after (POST) BR. Blood flow response was evaluated in the common femoral artery by Eco-Doppler during 1-min passive leg movements (PLM). The intramuscular matching between O₂ delivery and O₂ utilization was evaluated by near-infrared spectroscopy (NIRS). Mitochondrial respiration was evaluated ex vivo by high-resolution respirometry in isolated muscle fibers, and in vivo by NIRS by the evaluation of skeletal muscle V̇O₂(V̇O₂m) recovery kinetics. Resting V̇O₂m was estimated by NIRS. Peak V̇O₂p was lower in POST vs. PRE. The area under the blood flow vs. time curve during PLM was smaller (P = 0.03) in POST (274 ± 233 mL) vs. PRE (427 ± 291). An increased (P = 0.03) overshoot of muscle deoxygenation during a metabolic transition was identified in POST. Skeletal muscle citrate synthase activity was not different (P = 0.11) in POST (131 ± 16 nmol. min^-1. mg^-1) vs. PRE (138 ± 19). Maximal ADP-stimulated mitochondrial respiration (66 ± 18 pmol. s^-1. mg^-1 [POST] vs. 72 ± 14 [PRE], P = 0.41) was not affected by BR. Apparent K_m for ADP sensitivity of mitochondrial respiration was reduced in POST vs. PRE (P = 0.04). The V̇O₂m recovery time-constant was not different (P = 0.79) in POST (22 ± 6 s) vs. PRE (22 ± 6). Resting V̇O₂m was reduced by 25% in POST vs. PRE (P = 0.006). Microvascular-endothelial function was impaired following a 10-day BR, whereas mitochondrial mass and function (both in vivo and ex vivo) were unaffected or slightly enhanced. • Keywords: NIRS, PLM, Bed rest, Microgravity, Mitochondrial respiration, Oxidative metabolism, Skeletal muscle • Bioblast editor: Plangger M

Labels: MiParea: Respiration, Exercise physiology;nutrition;life style 

Organism: Human  Tissue;cell: Skeletal muscle  Preparation: Permeabilized tissue 

Coupling state: LEAK, OXPHOS, ET  Pathway: N, S, NS, ROX  HRR: Oxygraph-2k 

2021-09