Mark Wefers Bettink

Chapter 5 84 Abstract Mitochondrial function has been predominantly measured ex vivo . Due to isolation and preservation procedures ex vivo measurements might misrepresent in vivo mitochondrial conditions. Direct measurement of in vivo mitochondrial oxygen tension (mitoPO 2 ) and oxygen disappearance rate (ODR) with the protoporphyrin IX-triplet state lifetime technique (PpIX-TSLT) might increase our understanding of mitochondrial dysfunction in the pathophysiology of acute disease. LPS administration decreased mitochondrial respiration (ODR) in vivo but did not alter mitochondrial function as assessed with ex vivo techniques (high resolution respirometry and specific complex determinations). PpIX-TSLT measures in vivo mitoPO 2 and ODR and can be applied non-invasively at the skin. Key words: Mitochondria, Endotoxemia, Lipopolysaccharides, Succinic Acid, 5-aminolevulinic acid.