TY - GEN
T1 - The role of endothelial nitric oxide synthase (eNOS) uncoupling in acute hyperglycemia – induced oxidative stress and vascular endothelial dysfunction by measuring blood nitric oxide and hydrogen peroxide in real-time
AU - Bertolet, Matthew
AU - Minni, Michael
AU - Barsotti, Robert J.
AU - Young, Lindon H.
AU - Chen, Qian
PY - 2013/5/1
Y1 - 2013/5/1
N2 - Acute hyperglycemia can impair vascular endothelial function in non-diabetic subjects in addition to diabetic patients. Decreased eNOS derived nitric oxide (NO) bioavailability and increased reactive oxygen species (ROS), such as superoxide (SO) and hydrogen peroxide (H 2 O 2 ), are the major characteristics of vascular endothelial dysfunction. Furthermore, eNOS can change from coupled to an uncoupled status resulting in SO production instead of NO production. The role of eNOS uncoupling in acute hyperglycemia induced vascular dysfunction is unclear in vivo. In this study we hypothesized that acute hyperglycemia (200 mg/dL) would increase H 2 O 2 and decrease NO release in blood relative to saline control. By contrast, 5,6,7,8-tetrahydrobiopterin (BH 4 , an essential cofactor of coupled eNOS) (MW=241.247 g/mol, 6.5 mg/kg) or L-arginine (the substrate of coupled eNOS) (MW=210.66 g/mol, 600 mg/kg) would attenuate acute hyperglycemia-induced blood NO/H 2 O 2 change. However, 7,8-dihydrobiopterin (BH 2 , an oxidized form of BH 4 and serves as a cofactor for uncoupled eNOS) (MW=239.231 g/mol, 4 mg/kg) will exacerbate acute hyperglycemia-induced blood NO/H 2 O 2 change. Blood NO or H 2 O 2 levels were measured simultaneously using calibrated NO or H 2 O 2 microsensors (100 µm WPI Inc.) by placing them into the femoral veins of male Sprague-Dawley rats. The electrical traces were recorded at baseline and throughout 3 hours of infusion with saline or 20% D-glucose with or without a drug and converted into concentration based on the calibration curve. We found that acute hyperglycemia (200 mg/dL) significantly increased H 2 O 2 (n=6) and reduced NO (n=6) blood levels compared to the saline group (n=7, p2 exacerbated hyperglycemia– induced increased H 2 O 2 levels (n=7) and decreased NO levels (n=4) (p4 (n=6), significantly attenuated hyperglycemia– induced increased H 2 O 2 levels and decreased NO levels (p2O 2 (n=5) and NO (n=6) blood levels as BH 4 , showing significant reduction of blood H 2 O 2 and enhancement of blood NO (p2O 2 and reduced NO blood levels. Uncoupled eNOS serves as a significant source mediating acute hyperglycemia-induced vascular dysfunction. Therefore, promotion of eNOS coupling may be effective in protecting vascular endothelial function from hyperglycemic insult.
AB - Acute hyperglycemia can impair vascular endothelial function in non-diabetic subjects in addition to diabetic patients. Decreased eNOS derived nitric oxide (NO) bioavailability and increased reactive oxygen species (ROS), such as superoxide (SO) and hydrogen peroxide (H 2 O 2 ), are the major characteristics of vascular endothelial dysfunction. Furthermore, eNOS can change from coupled to an uncoupled status resulting in SO production instead of NO production. The role of eNOS uncoupling in acute hyperglycemia induced vascular dysfunction is unclear in vivo. In this study we hypothesized that acute hyperglycemia (200 mg/dL) would increase H 2 O 2 and decrease NO release in blood relative to saline control. By contrast, 5,6,7,8-tetrahydrobiopterin (BH 4 , an essential cofactor of coupled eNOS) (MW=241.247 g/mol, 6.5 mg/kg) or L-arginine (the substrate of coupled eNOS) (MW=210.66 g/mol, 600 mg/kg) would attenuate acute hyperglycemia-induced blood NO/H 2 O 2 change. However, 7,8-dihydrobiopterin (BH 2 , an oxidized form of BH 4 and serves as a cofactor for uncoupled eNOS) (MW=239.231 g/mol, 4 mg/kg) will exacerbate acute hyperglycemia-induced blood NO/H 2 O 2 change. Blood NO or H 2 O 2 levels were measured simultaneously using calibrated NO or H 2 O 2 microsensors (100 µm WPI Inc.) by placing them into the femoral veins of male Sprague-Dawley rats. The electrical traces were recorded at baseline and throughout 3 hours of infusion with saline or 20% D-glucose with or without a drug and converted into concentration based on the calibration curve. We found that acute hyperglycemia (200 mg/dL) significantly increased H 2 O 2 (n=6) and reduced NO (n=6) blood levels compared to the saline group (n=7, p2 exacerbated hyperglycemia– induced increased H 2 O 2 levels (n=7) and decreased NO levels (n=4) (p4 (n=6), significantly attenuated hyperglycemia– induced increased H 2 O 2 levels and decreased NO levels (p2O 2 (n=5) and NO (n=6) blood levels as BH 4 , showing significant reduction of blood H 2 O 2 and enhancement of blood NO (p2O 2 and reduced NO blood levels. Uncoupled eNOS serves as a significant source mediating acute hyperglycemia-induced vascular dysfunction. Therefore, promotion of eNOS coupling may be effective in protecting vascular endothelial function from hyperglycemic insult.
UR - https://digitalcommons.pcom.edu/research_day/research_day2013/research2013/33
M3 - Other contribution
ER -