Early determinants of H2O2-induced endothelial dysfunction.
Reactive oxygen species (ROS) can stimulate nitric oxide (NO(*)) production from the endothelium by transient activation of endothelial nitric oxide synthase (eNOS). With continued or repeated exposure, NO(*) production is reduced, however. We investigated the early determinants of this decrease in NO(*) production. Following an initial H(2)O(2) exposure, endothelial cells responded by increasing NO(*) production measured electrochemically. NO(*) concentrations peaked by 10 min with a slow reduction over 30 min. The decrease in NO(*) at 30 min was associated with a 2.7-fold increase in O(2)(*-) production (p < 0.05) and a 14-fold reduction of the eNOS cofactor, tetrahydrobiopterin (BH(4), p < 0.05). Used as a probe for endothelial dysfunction, the integrated NO(*) production over 30 min upon repeated H(2)O(2) exposure was attenuated by 2.1-fold (p = 0.03). Endothelial dysfunction could be prevented by BH(4) cofactor supplementation, by scavenging O(2)(*-) or peroxynitrite (ONOO(-)), or by inhibiting the NADPH oxidase. Hydroxyl radical (()OH) scavenging did not have an effect. In summary, early H(2)O(2)-induced endothelial dysfunction was associated with a decreased BH(4) level and increased O(2)(*-) production. Dysfunction required O(2)(*-), ONOO(-), or a functional NADPH oxidase. Repeated activation of the NADPH oxidase by ROS may act as a feed forward system to promote endothelial dysfunction.
Boulden
Beth M
BM
Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA 30322, USA.
Widder
Julian D
JD
Allen
Jon C
JC
Smith
Debra A
DA
Al-Baldawi
Ruaa N
RN
Harrison
David G
DG
Dikalov
Sergey I
SI
Jo
Hanjoong
H
Dudley
Samuel C
SC
D000818:Animals; D001011:Aorta / Q000378:metabolism; D001708:Biopterins / Q000031:analogs & derivatives / Q000494:pharmacology; D002417:Cattle; D004730:Endothelium, Vascular / Q000378:metabolism* / Q000473:pathology*; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D017665:Hydroxyl Radical; D008954:Models, Biological; D009569:Nitric Oxide / Q000737:chemistry / Q000378:metabolism; D010100:Oxygen / Q000378:metabolism; D017382:Reactive Oxygen Species; D013481:Superoxides / Q000378:metabolism; D013997:Time Factors
D017382:Reactive Oxygen Species; D013481:Superoxides; D001708:Biopterins; D009569:Nitric Oxide; D017665:Hydroxyl Radical; D006861:Hydrogen Peroxide; C003402:sapropterin; D010100:Oxygen