Details

Autor(en) / Beteiligte

• Liu, Yanping
• Zhao, Hongtao
• Li, Hongwei
• Kalyanaraman, B
• Nicolosi, Alfred C
• Gutterman, David D

Titel

Mitochondrial Sources of H2O2 Generation Play a Key Role in Flow-Mediated Dilation in Human Coronary Resistance Arteries

Ist Teil von

• Circulation research, 2003-09, Vol.93 (6), p.573-580

Ort / Verlag

Hagerstown, MD: American Heart Association, Inc

Erscheinungsjahr

2003

Quelle

MEDLINE

Beschreibungen/Notizen

• ABSTRACT—We previously showed that hydrogen peroxide (H2O2) contributes to flow-induced dilation in human coronary resistance arteries (HCRAs); however, the source of this H2O2 is not known. We hypothesized that the H2O2 is derived from superoxide (O2) generated by mitochondrial respiration. HCRAs were dissected from right atrial appendages obtained from patients during cardiac surgery and cannulated with micropipettes. H2O2-derived radicals and O2 were detected by electron spin resonance (ESR) using BMPO as the spin trap and by histofluorescence using hydroethidine (HE, 5 μmol/L) and dichlorodihydrofluorescein (DCFH, 5 μmol/L). Diameter changes to increases in pressure gradients (20 and 100 cm H2O) were examined in the absence and the presence of rotenone (1 μmol/L), myxothiazol (100 nmol/L), cyanide (1 μmol/L), mitochondrial complex I, III, and IV inhibitors, respectively, and apocynin (3 mmol/L), a NADPH oxidase inhibitor. At a pressure gradient of 100 cm H2O, ubisemiquinone and hydroxyl radicals were detected from effluents of vessels. Including superoxide dismutase and catalase in the perfusate reduced the ESR signals. Relative ethidium and DCFH fluorescence intensities in HCRAs exposed to flow were enhanced (1.45±0.15 and 1.57±0.12, respectively compared with no-flow) and were inhibited by rotenone (0.87±0.17 and 0.95±0.07). Videomicroscopic studies showed that rotenone and myxothiazol blocked flow-induced dilation (% max. dilation at 100 cm H2Orotenone, 74±3% versus 3±13%; myxothiazol, 67±3% versus 28±4%; P <0.05). Neither cyanide nor apocynin altered flow-induced dilation. These results suggest that shear stress induced H2O2 formation, and flow-induced dilation is derived from O2 originating from mitochondrial respiration.