Endothelin Mediates Superoxide Production and Vasoconstriction through Activation of NADPH Oxidase and Uncoupled Nitric-Oxide Synthase in the Rat Aorta

Abstract

Experiments were designed to test the hypothesis that elevated levels of endothelin 1 (ET-1) in the vasculature activate NADPH oxidase and/or uncoupled nitric-oxide synthase (NOS), resulting in O 2. production, and mediate increased constriction. Rat aortic rings were incubated with ET-1 or vehicle in the presence and absence of superoxide dismutase (SOD), ebselen (glutathione peroxidase mimetic), apocynin (NADPH oxidase inhibitor), L-NAME (N -nitro-L-arginine methyl ester) (NOS inhibitor), tetrahydrobiopterin (BH 4 ) (NOS cofactor), or selective ET A and. production was monitored by oxidized dihydroethidine staining and/or lucigenin chemiluminescence. ET-1 significantly increased O 2 .production compared with vehicle. SOD, ebselen, and apocynin inhibited the ET-1-induced increase in O 2 . in intact and endothelium-denuded aorta. L-NAME and BH 4 inhibited the ET-1-induced increase in O 2 . in intact tissue, whereas these two compounds had no effect on ET-1-induced O 2 . in endotheliumdenuded aorta. Preincubation with BQ-123 or A-192621, individually, had no effect on ET-1-induced O 2 . ; however combining both antagonists inhibited the ET-1-stimulated increase in O 2 . .Rat aortic rings were incubated with ET-1 or vehicle in the presence or absence of sepiapterin (BH 4 synthesis substrate) or apocynin and mounted on wire myographs to determine isometric force generation in response to increasing KCl concentrations. ET-1 increased the contractile response to KCl compared with vehicle. Treatment with either sepiapterin or apocynin attenuated the ET-1-mediated increase with no effect of sepiapterin or apocynin alone. These data support the hypothesis that ET-1 increases vascular tone, in part, through ET A /ET B receptor activation of O 2 . production from NADPH oxidase and NOS uncoupling.

Endothelin A Receptor Blockade Reduces Diabetic Renal Injury via an Anti-Inflammatory Mechanism

“…Based on findings that ET A receptor activation stimulates NADPH oxidase to produce superoxide (10,13,53) and that the NADPH oxidase inhibitor apocynin prevents proteinuria and reduces renal injury in diabetes (8), we proposed that blockade of ET A receptors would reduce oxidative stress in the kidney of diabetic rats and therefore reduce renal injury. To address this postulate, we measured lipid peroxidation, hydrogen peroxide excretion, DNA damage, and expression of NADPH oxidase subunits as indices of oxidative stress.…”

CPU0213, a novel endothelin type A and type B receptor antagonist, protects against myocardial ischemia/reperfusion injury in rats

“…In addition, oxidative stress can elevate ET-1 levels, and ET-1 has been demonstrated to increase the production of reactive oxygen species (ROS) (31). Although oxidative stress is an established consequence of ET A receptor activation, a similar action of the ET B receptor remains controversial (32,33).…”

The role of endothelin-1 and new therapeutic approaches in sepsis and septic shock

“…Bu peptit intravenöz verildiğinde başlangıçta kan damarlarının dilatasyonuna ardın-dan uzun süren konstriksiyona yaparak iç organlarda iskemi ve endotel işlevinde bozukluğa neden olmaktadır. Oluştur-duğu bu değişikliklerle çok miktarda ROT açığa çıkmasını sağlamaktadır (82)(83)(84).…”