Healthy vascular function is primarily regulated by several factors including EDRF (endothelium-dependent relaxing factor), EDCF (endothelium-dependent contracting factor) and EDHF (endothelium-dependent hyperpolarizing factor). Vascular dysfunction or injury induced by aging, smoking, inflammation, trauma, hyperlipidaemia and hyperglycaemia are among a myriad of risk factors that may contribute to the pathogenesis of many cardiovascular diseases, such as hypertension, diabetes and atherosclerosis. However, the exact mechanisms underlying the impaired vascular activity remain unresolved and there is no current scientific consensus. Accumulating evidence suggests that the inflammatory cytokine TNF (tumour necrosis factor)-α plays a pivotal role in the disruption of macrovascular and microvascular circulation both in vivo and in vitro. AGEs (advanced glycation end-products)/RAGE (receptor for AGEs), LOX-1 [lectin-like oxidized low-density lipoprotein receptor-1) and NF-κB (nuclear factor κB) signalling play key roles in TNF-α expression through an increase in circulating and/or local vascular TNF-α production. The increase in TNF-α expression induces the production of ROS (reactive oxygen species), resulting in endothelial dysfunction in many pathophysiological conditions. Lipid metabolism, dietary supplements and physical activity affect TNF-α expression. The interaction between TNF-α and stem cells is also important in terms of vascular repair or regeneration. Careful scrutiny of these factors may help elucidate the mechanisms that induce vascular dysfunction. The focus of the present review is to summarize recent evidence showing the role of TNF-α in vascular dysfunction in cardiovascular disease. We believe these findings may prompt new directions for targeting inflammation in future therapies.

Cytochrome P450 epoxygenases convert arachidonic acid into 4 epoxyeicosatrienoic acid (EET) regioisomers, which were recently identified as endothelium-derived hyperpolarizing factors in coronary blood vessels. Both EETs and their dihydroxyeicosatrienoic acid (DHET) metabolites have been shown to relax conduit coronary arteries at micromolar concentrations, whereas the plasma concentrations of EETs are in the nanomolar range. However, the effects of EETs and DHETs on coronary resistance arterioles have not been examined. We administered EETs and DHETs to isolated canine coronary arterioles (diameter, 90.0+/-3.4 microm; distending pressure, 20 mm Hg) preconstricted by 30% to 60% of the resting diameter with endothelin. All 4 EET regioisomers produced potent, concentration-dependent vasodilation (EC50 values ranging from -12.7 to -10.1 log [M]) and were approximately 1000 times more potent than reported in conduit coronary arteries. The vasodilation produced by 14,15-EET was not attenuated by removal of the endothelium and indicated a direct action of 14,15-EET on microvascular smooth muscle. Likewise, 14,15-DHET, 11,12-DHET, 8,9-DHET, and the delta-lactone of 5,6-EET produced extremely potent vasodilation (EC50 values ranging from -15.8 to -13.1 log [M]). The vasodilation produced by these eicosanoids was highly potent in comparison to that produced by other vasodilators, including arachidonic acid (EC50=-7.5 log [M]). The epoxide hydrolase inhibitor, 4-phenylchalone oxide, which blocked the conversion of [3H]14,15-EET to [3H]14,15-DHET by canine coronary arteries, did not alter arteriolar dilation to 11,12-EET; thus, the potent vasodilation induced by EETs does not require formation of DHETs. In contrast, charybdotoxin (a KCa channel inhibitor) and KCl (a depolarizing agent) blocked vasodilation by 11,12-EET and 11,12-DHET. We conclude that EETs and DHETs potently dilate canine coronary arterioles via activation of KCa channels. The preferential ability of these compounds to dilate resistance blood vessels suggests that they may be important regulators of coronary circulation.

Background— Angiotensin II (Ang II) contributes to vascular pathology in part by stimulating NADPH oxidase activity, leading to increased formation of superoxide (O 2 − ). We reported that O 2 − levels, NADPH oxidase activity, and expression of the p47 phox subunit of NADPH oxidase are increased in human abdominal aortic aneurysms (AAAs). Here, we tested the hypothesis that deletion of p47 phox will attenuate oxidative stress and AAA formation in Ang II–infused apoE −/− mice. Methods and Results— Male apoE −/− and apoE −/− p47 phox −/− mice received saline or Ang II (1000 ng · kg −1 · min −1 ) infusion for 28 days, after which abdominal aortic weight and maximal diameter were determined. Aortic tissues and blood were examined for parameters of aneurysmal disease and oxidative stress. Ang II infusion induced AAAs in 90% of apoE −/− versus 16% of apo −/− p47 phox −/− mice ( P <0.05). Abdominal aortic weight (14.1±3.2 versus 35.6±9.0 mg), maximal aortic diameter (1.5±0.2 versus 2.4±0.4 mm), aortic NADPH oxidase activity, and parameters of oxidative stress were reduced in apoE −/− p47 phox −/− mice compared with apoE −/− mice ( P <0.05). In addition, aortic macrophage infiltration and matrix metalloproteinase-2 activity were reduced in apoE −/− p47 phox −/− mice compared with apoE −/− mice. Deletion of p47 phox attenuated the pressor response to Ang II; however, coinfusion of phenylephrine with Ang II, which restored the Ang II pressor response, did not alter the protective effects of p47 phox deletion on AAA formation. Conclusions— Deletion of p47 phox attenuates Ang II–induced AAA formation in apoE −/− mice, suggesting that NADPH oxidase plays a critical role in AAA formation in this model.