Authors: Ulla F Rasmussen Peter Krustrup Jens Bangsbo Hans N Rasmussen
Publish Date: 2001/08/31
Volume: 443, Issue: 2, Pages: 180-187
Abstract
Six young men performed five 1min bicycle exercise bouts to exhaustion Muscle lactate increased to ≅114 mmol kg–1 dwt and pH decreased to ≅66 Mitochondria were prepared from a needle biopsy sample taken from m vastus lateralis immediately after the last exercise bout No significant effect of exhaustion on the proton permeability and amount of cytochromes c and aa3 in isolated mitochondria was detected The activities of the following enzymes and systems were not altered either citrate synthase succinate dehydrogenase cytochrome oxidase succinate + glutamate respiration malate + glutamate respiration the respiratory chain and the reactions involved in ATP synthesis Thus the mitochondria did not appear globally altered upon exhaustion However the following NADlinked activities were significantly lowered pyruvate dehydrogenase αketoglutarate dehydrogenase glutamate dehydrogenase and fatty acid βoxidation The activities of αglycerophosphate dehydrogenase and exoNADH oxidase enzymes that might catalyze the oxidation of sarcoplasmic NADH were increased These changes may be due to the action of reactive oxygen species protons and Ca2+ Transient opening of the permeability transition pore may also be involved Some effects may have been reversed during isolation of the mitochondria and the changes in mitochondrial function in situ upon exhaustion may have been more extensive than observed
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