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Myoglobin facilitates oxygen diffusion
Author(s) -
Merx Marc W.,
Flögel Ulrich,
Stumpe Thomas,
Gödecke Axel,
Decking Ulrich K. M.,
Schrader Jürgen
Publication year - 2001
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fsb2fj000497fje
Subject(s) - myoglobin , chemistry , oxygen , medicine , oxygenation , oxygen–haemoglobin dissociation curve , oxidative phosphorylation , perfusion , hemodynamics , retrograde perfusion , intracellular , endocrinology , cardiology , biochemistry , organic chemistry
In this study, the hemodynamic effects of acute myoglobin (Mb) inhibition with CO on isolated hearts of wild‐type (WT) mice were examined at different degrees of oxygenation. Hearts from myoglobin knockout (myo −/− ) mice served as appropriate controls. The intracellular MbO2 dissociation curve, as measured by 1 H NMR, was determined by systematically lowering the O2 content of the perfusion medium. At 100% MbO2 saturation (buffer O2: 75%), complete inhibition of Mb with 20% CO did not alter left ventricular developed pressure (LVDP) or coronary venous PO 2 (P v O 2 ) and thus myocardial O 2 consumption. At 87% MbO 2 saturation (buffer O2: 65%), CO applied to WT hearts significantly decreased LVDP by 12% and increased P v O 2 by 30% (both P<<0.005) respectively, whereas no effects were observed in myo −/− hearts. Cell width in isolated myo −/− as compared with WT cardiomyocytes was reduced (4.8 μm vs. 5.4 μm, P<0.001), whereas cell length did not differ. At ambient PO 2 of 8 mm Hg, oxygen consumption of stimulated myo −/− cardiomyocytes was only 60% that of WT controls (P<0.001). Our results do not support Mb‐mediated oxidative phosphorylation in the beating mouse heart. However, we find conclusive evidence that Mb is important in facilitating O 2 diffusion from the vasculature to mitochondrial cytochromes and that the oxygen reservoir of myoglobin is of functional relevance in the beating mammalian heart.