Obligatory Role of Intraluminal O2− in Acute Endothelin-1 and Angiotensin II Signaling to Mediate Endothelial Dysfunction and MAPK Activation in Guinea-Pig Hearts

Abstract

Abstract:We hypothesized that, due to a cross-talk between cytoplasmic O2 − -sources and intraluminally expressed xanthine oxidase (XO), intraluminal O2 − is instrumental in mediating intraluminal (endothelial dysfunction) and cytosolic (p38 and ERK1/2 MAPKs phosphorylation) manifestations of vascular oxidative stress induced by endothelin-1 (ET-1) and angiotensin II (AT-II). Isolated guinea-pig hearts were subjected to 10-min agonist perfusion causing a burst of an intraluminal O2 − . ET-1 antagonist, tezosentan, attenuated AT-II-mediated O2 − , indicating its partial ET-1 mediation. ET-1 and Ang-T (AT-II + tezosentan) triggered intraluminal O2 − , endothelial dysfunction, MAPKs and p47phox phosphorylation, and NADPH oxidase (Nox) and XO activation. These effects were: (i) prevented by blocking PKC (chelerythrine), Nox (apocynin), mitochondrial ATP-dependent K + channel (5-HD), complex II (TTFA), and XO (allopurinol); (ii) mimicked by the activation of Nox (NADH); and mitochondria (diazoxide, 3-NPA) and (iii) the effects by NADH were prevented by 5-HD, TTFA and chelerythrine, and those by diazoxide and 3-NPA by apocynin and chelerythrine, suggesting that the agonists coactivate Nox and mitochondria, which further amplify their activity via PKC. The effects by ET-1, Ang-T, NADH, diazoxide, and 3-NPA were opposed by blocking intraluminal O2 − (SOD) and XO, and were mimicked by XO activation (hypoxanthine). Apocynin, TTFA, chelerythrine, and SOD opposed the effects by hypoxanthine. In conclusion, oxidative stress by agonists involves

Activation of Coronary Arteriolar PKCβ2 Impairs Endothelial NO-Mediated Vasodilation: Role of JNK/Rho Kinase Signaling and Xanthine Oxidase Activation

“…It also cannot be excluded that the high concentration of PMA (0.5 µM) used in the above cell culture study might also have triggered other signaling pathways for NAD(P)H oxidase activation. Our results are consistent with a previous study showing that the PKC-dependent xanthine oxidase-mediated superoxide production contributes to coronary endothelial dysfunction and NO deficiency in the heart perfused with inflammatory vasoconstrictor endothelin-1 or angiotensin-II [ 63 ]. Xanthine oxidase is also a major source of superoxide to compromise endothelial function and NO bioavailability in porcine [ 21 ] and murine [ 64 ] coronary arterioles subjected to inflammatory insults and in hypertensive/hypercholesterolemic patients exhibiting impaired coronary endothelium-dependent vasodilation [ 65 ].…”

Cardiac and renal upregulation of Nox2 and NF-κB and repression of Nox4 and Nrf2 in season- and diabetes-mediated models of vascular oxidative stress in guinea-pig and rat

“…; Wojtera et al. ). In line with this, we have reported before that the inhibitors of Nox (apocynin), xanthine oxidase (allopurinol), and NOS (L‐NMMA) have been effective in blocking seasonal O 2 − ‐overproduction in the guinea‐pig heart (Konior et al.…”

“…The vasodilator response to acetylcholine (ACh), serving as a measure of the agonist‐induced endothelium‐dependent vascular function, was studied in isolated guinea‐pig hearts, as described before (Wojtera et al. ). Coronary flow was recorded continuously and a 50 μ L bolus of 10 μ mol·L ‐1 ACh was injected into the aortic cannula.…”

Enjoy your heart-beets. The role of dietary inorganic nitrate in cardiovascular health

“…Nox1/2 constitutively generate O 2 -, which in turn stimulates O 2 -generation by other enzymatic systems (mitochondria, xanthine oxidase, and eNOS) [3,20,21]. Once generated, O 2 -initiates a cascade of oxidative reactions causing the generation of other ROS ( The major mechanism of the cellular signalisation by O 2 -and H 2 O 2 involves oxidative modification of protein cysteine thiols (Fig.…”