Boushel 2011 Mitochondrion
|Boushel RC, Gnaiger E, Calbet JA, Gonzalez-Alonso J, Wright-Paradis C, Sondergaard H, Ara I, Helge JW, Saltin B (2011) Muscle mitochondrial capacity exceeds maximal oxygen delivery in humans. Mitochondrion 11:303-7.|
Abstract: Across a wide range of species and body mass a close matching exists between maximal conductive oxygen delivery and mitochondrial respiratory rate. In this study we investigated in humans how closely in vivo maximal oxygen consumption (VO(2)max) is matched to muscle tissue-specific OXPHOS capacity (State 3) respiration. High-resolution respirometry was used to quantify mitochondrial respiration from the biopsies of arm and leg muscles while in vivo arm and leg VO(2) were determined by the Fick method during leg cycling and arm cranking. We hypothesized that muscle mitochondrial respiratory rate exceeds that of systemic oxygen delivery. OXPHOS capacity of the deltoid muscle (4.3±0.4 mmol O(2)kg(-1)min(-1)) was similar to the in vivo VO(2) during maximal arm cranking (4.7±0.5 mmol O(2)kg(-1)min(-1)) with 6 kg muscle. In contrast, the mitochondrial OXPHOS capacity of the quadriceps was 6.9±0.5 mmol O(2)kg(-1)min(-1), exceeding the in vivo leg VO(2)max (5.0±0.2mmolO(2)kg(-1)min(-1)) during leg cycling with 20 kg muscle (P<0.05). Thus, when half or more of the body muscle mass is engaged during exercise, muscle mitochondrial respiratory capacity surpasses in vivo VO(2)max. The findings reveal an excess capacity of muscle mitochondrial respiratory rate over O(2) delivery by the circulation in the cascade defining maximal oxidative rate in humans.
Labels: MiParea: Respiration, mt-Biogenesis;mt-density, Exercise physiology;nutrition;life style Mammal;model: Human Tissue;cell: Skeletal muscle Preparation: Intact organism, Permeabilized tissue Stress: Ischemia-reperfusion Coupling state: OXPHOS Substrate state: CI&II HRR: Oxygraph-2k
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