Endothelial cell respiration is affected by the oxygen tension during shear exposure: role of mitochondrial peroxynitrite.
Cultured vascular endothelial cell (EC) exposure to steady laminar shear stress results in peroxynitrite (ONOO(-)) formation intramitochondrially and inactivation of the electron transport chain. We examined whether the "hyperoxic state" of 21% O(2), compared with more physiological O(2) tensions (Po(2)), increases the shear-induced nitric oxide (NO) synthesis and mitochondrial superoxide (O(2)(*-)) generation leading to ONOO(-) formation and suppression of respiration. Electron paramagnetic resonance oximetry was used to measure O(2) consumption rates of bovine aortic ECs sheared (10 dyn/cm(2), 30 min) at 5%, 10%, or 21% O(2) or left static at 5% or 21% O(2). Respiration was inhibited to a greater extent when ECs were sheared at 21% O(2) than at lower Po(2) or left static at different Po(2). Flow in the presence of an endothelial NO synthase (eNOS) inhibitor or a ONOO(-) scavenger abolished the inhibitory effect. EC transfection with an adenovirus that expresses manganese superoxide dismutase in mitochondria, and not a control virus, blocked the inhibitory effect. Intracellular and mitochondrial O(2)(*-) production was higher in ECs sheared at 21% than at 5% O(2), as determined by dihydroethidium and MitoSOX red fluorescence, respectively, and the latter was, at least in part, NO-dependent. Accumulation of NO metabolites in media of ECs sheared at 21% O(2) was modestly increased compared with ECs sheared at lower Po(2), suggesting that eNOS activity may be higher at 21% O(2). Hence, the hyperoxia of in vitro EC flow studies, via increased NO and mitochondrial O(2)(*-) production, leads to enhanced ONOO(-) formation intramitochondrially and suppression of respiration.
Jones
Charles I
CI
Davis Heart and Lung Research Institute, Department of Internal Medicine, The Ohio State University, Columbus, OH 43210, USA.
Han
Zhaosheng
Z
Presley
Tennille
T
Varadharaj
Saradhadevi
S
Zweier
Jay L
JL
Ilangovan
Govindasamy
G
Alevriadou
B Rita
BR
D000818:Animals; D001011:Aorta / Q000166:cytology; D002417:Cattle; D019069:Cell Respiration; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000378:metabolism*; D004730:Endothelium, Vascular / Q000378:metabolism; D008928:Mitochondria / Q000378:metabolism*; D009569:Nitric Oxide / Q000096:biosynthesis; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism; D010100:Oxygen / Q000378:metabolism*; D010101:Oxygen Consumption; D010313:Partial Pressure; D030421:Peroxynitrous Acid / Q000096:biosynthesis*; D010766:Phosphorylation; D017382:Reactive Oxygen Species / Q000378:metabolism; D033081:Shear Strength; D013314:Stress, Mechanical; D013482:Superoxide Dismutase / Q000378:metabolism; D013481:Superoxides / Q000378:metabolism
D017382:Reactive Oxygen Species; D013481:Superoxides; D030421:Peroxynitrous Acid; D009569:Nitric Oxide; D052250:Nitric Oxide Synthase Type III; D013482:Superoxide Dismutase; D010100:Oxygen