The transforming growth factor-␤ superfamily member bone morphogenetic protein-2 (BMP-2) is up-regulated in atherosclerotic arteries; however, its effects on the endothelium are not well characterized. Using microdissected coronary arterial endothelial cells (CAECs) and cultured primary CAECs, we demonstrated endothelial mRNA expression of BMP-2 and BMP-4. The proinflammatory cytokine tumor necrosis factor-␣ and H 2 O 2 significantly increased endothelial expression of BMP-2 but not BMP-4. In organ culture, BMP-2 substantially decreased relaxation of rat carotid arteries to acetylcholine and increased production of reactive oxygen species, events inhibited by pharmacologically blocking protein kinase C (PKC) or NAD(P)H oxidase. BMP-2 activated nuclear factor-〉 in CAECs, and BMP-2 and BMP-4 substantially increased adhesion of monocytic THP-1 cells, which was reduced by pharmacologically inhibiting p42/44 MAP kinase pathway (also by siRNA downregulating ERK-1/2) or PKC. Incubation of rat carotid arteries with BMP-2 ex vivo also increased adhesion of mononuclear cells to the endothelium, requiring p42/44 MAP kinase and PKC. Western blotting showed that in CAECs and carotid arteries BMP-2 elicited phosphorylation of p42/44 MAP kinase, which was reduced by blocking MAP kinase kinase and PKC. Collectively, expression of BMP-2 is regulated by proinflammatory stimuli, and increased levels of BMP-2 induce endothelial dysfunction, oxidative stress, and endothelial activation. The cytokine bone morphogenetic protein-2 (BMP-2), a transforming growth factor superfamily member, was originally detected in cartilage and bone 1 ; however, recent studies demonstrated that vascular endothelial and smooth muscle cells are also a significant source of BMPs.2-7 Genetic analysis of patients with primary pulmonary hypertension indicated that a vascular BMP-2/ BMP receptor system plays an important role in vascular physiology.8,9 BMP-2 is known to regulate a host of cellular functions, 2,4,5,10 including cardiovascular development, 10 neovascularization in bone 7 and tumors, 11 and smooth muscle cell chemotaxis.2 Endothelium-derived BMP-2 is osteoinductive 5,7 and hypotheses have been put forward that BMPs may contribute to vascular calcification. 3,5,12 Despite evidence for the physiological/ pathophysiological importance of BMP-2 the regulation of BMP-2 expression and the effects exerted by BMP-2 on endothelial function and phenotype have yet to be clearly elucidated.Previously, we have demonstrated that in coronary arteries in hyperhomocysteinemia vascular inflammation and up-regulation of tumor necrosis factor (TNF)-␣ is associated with an increased vascular BMP-2 expression. 13 Importantly, recent studies confirmed a striking up-regulation of BMPs in atherosclerotic lesions.2-4 BMP-4 (which is related to BMP-2 by its amino acid sequence but is transcribed from an entirely different gene) 4,6 was shown to exert proinflammatory effects by enhancing monocyte adhesion to the endothelium. On the basis of the aforementioned findings we h...

Because systems controlled by basal NAD(P)H oxidase activity appear to contribute to differences in responses of endothelium-removed bovine coronary (BCA) and pulmonary (BPA) arteries to hypoxia, we characterized the Nox oxidases activities present in these vascular segments and how cytosolic NAD(P)H redox systems could be controlling oxidase activity. BPA generated approximately 60-80% more lucigenin (5 microM) chemiluminescence detectable superoxide than BCA. Apocynin (10 microM), a NAD(P)H oxidase inhibitor, and 6-aminonicotinamide (1 mM), a pentose phosphate inhibitor (PPP), both attenuated (approximately by 50-70%) superoxide detected in BPA and BCA. There was no significant difference in the expression of Nox2 or Nox4 mRNA or protein detected by Western blot analysis. NADPH and NADH increased superoxide in homogenates and isolated microsomal membrane fractions in a manner consistent with BPA and BCA having similar levels of oxidase activity. BPA had 4.2-fold higher levels of NADPH than BCA. The activity and protein levels of glucose-6-phosphate dehydrogenase (G6PD), the rate-limiting PPP enzyme generating cytosolic NADPH, were 1.5-fold higher in BPA than BCA. Thus BPA differ from BCA in that they have higher levels of G6PD activity, NADPH, and superoxide. Because both arteries have similar levels of Nox expression and activity, elevated levels of cytosolic NADPH may contribute to increased superoxide in BPA.

Wolin, Michael S., Mansoor Ahmad, and Sachin A. Gupte. Oxidant and redox signaling in vascular oxygen sensing mechanisms: basic concepts, current controversies, and potential importance of cytosolic NADPH. Am J Physiol Lung Cell Mol Physiol 289: L159 -L173, 2005; doi:10.1152/ajplung.00060.2005.-Vascular smooth muscle (VSM) derived from pulmonary arteries generally contract to hypoxia, whereas VSM from systemic arteries usually relax, indicating the presence of basic oxygen-sensing mechanisms in VSM that are adapted to the environment from which they are derived. This review considers how fundamental processes associated with the generation of reactive oxygen species (ROS) by oxidase enzymes, the metabolic control of cytosolic NADH, NADPH and glutathione redox systems, and mitochondrial function interact with signaling systems regulating vascular force in a manner that is potentially adapted to be involved in PO 2 sensing. Evidence for opposing hypotheses of hypoxia, either decreasing or increasing mitochondrial ROS, is considered together with the PO2 dependence of ROS production by Nox oxidases as sensors potentially contributing to hypoxic pulmonary vasoconstriction. Processes through which ROS and NAD(P)H redox changes potentially control interactive signaling systems, including soluble guanylate cyclase, potassium channels, and intracellular calcium are discussed together with the data supporting their regulation by redox in responses to hypoxia. Evidence for hypothesized potential differences between systemic and pulmonary arteries originating from properties of mitochondrial ROS generation and the redox sensitivity of potassium channels is compared with a new hypothesis in which differences in the control of cytosolic NADPH redox by the pentose phosphate pathway results in increased NADPH and Nox oxidase-derived ROS in pulmonary arteries, whereas lower levels of glucose-6-phosphate dehydrogenase in coronary arteries may permit hypoxia to activate a vasodilator mechanism controlled by oxidation of cytosolic NADPH. hydrogen peroxide; hypoxia; Nox oxidase; mitochondria; pentose phosphate pathway PROCESSES THAT POTENTIALLY FUNCTION AS OXYGEN SENSORSThe direct binding of O 2 to a protein such as the hemecontaining soluble guanylate cyclase (sGC) (31, 89) that is directly linked to the control of cellular function would be an ideal way of sensing changes in PO 2 . However, a protein of this type has not yet been identified in vascular tissue. The substrate requirement for enzymes that metabolize oxygen is usually one of the most fundamental mechanisms through which PO 2 is sensed at the cellular level. Although the oxygen requirement for mitochondrial energy metabolism needed for the generation of force is the most basic mechanism of tissue oxygen sensing, there are only a few instances where this process appears to be the primary mechanism present in blood vessels controlling their response to acute changes in force elicited by hypoxia (95,101). Thus other aspects of the activities of oxygen metabolizing enzym...

Background Tranexamic acid reduces surgical bleeding and reduces death due to bleeding in patients with trauma. Meta-analyses of small trials show that tranexamic acid might decrease deaths from gastrointestinal bleeding. We aimed to assess the effects of tranexamic acid in patients with gastrointestinal bleeding. Methods We did an international, multicentre, randomised, placebo-controlled trial in 164 hospitals in 15 countries. Patients were enrolled if the responsible clinician was uncertain whether to use tranexamic acid, were aged above the minimum age considered an adult in their country (either aged 16 years and older or aged 18 years and older), and had significant (defined as at risk of bleeding to death) upper or lower gastrointestinal bleeding. Patients were randomly assigned by selection of a numbered treatment pack from a box containing eight packs that were identical apart from the pack number. Patients received either a loading dose of 1 g tranexamic acid, which was added to 100 mL infusion bag of 0•9% sodium chloride and infused by slow intravenous injection over 10 min, followed by a maintenance dose of 3 g tranexamic acid added to 1 L of any isotonic intravenous solution and infused at 125 mg/h for 24 h, or placebo (sodium chloride 0•9%). Patients, caregivers, and those assessing outcomes were masked to allocation. The primary outcome was death due to bleeding within 5 days of randomisation; analysis excluded patients who received neither dose of the allocated treatment and those for whom outcome data on death were unavailable. This trial was registered with Current Controlled Trials, ISRCTN11225767, and ClinicalTrials.gov, NCT01658124.

Mingone, Christopher J., Sachin A. Gupte, Joseph L. Chow, Mansoor Ahmad, Nader G. Abraham, and Michael S. Wolin. Protoporphyrin IX generation from ␦-aminolevulinic acid elicits pulmonary artery relaxation and soluble guanylate cyclase activation. Am J Physiol Lung Cell Mol Physiol 291: L337-L344, 2006; doi:10.1152/ajplung.00482.2005.-Protoporphyrin IX is an activator of soluble guanylate cyclase (sGC), but its role as an endogenous regulator of vascular function through cGMP has not been previously reported. In this study we examined whether the heme precursor ␦-aminolevulinic acid (ALA) could regulate vascular force through promoting protoporphyrin IX-elicited activation of sGC. Exposure of endothelium-denuded bovine pulmonary arteries (BPA) in organoid culture to increasing concentrations of the heme precursor ALA caused a concentration-dependent increase in BPA epifluorescence, consistent with increased tissue protoporphyrin IX levels, associated with decreased force generation to increasing concentrations of serotonin. The force-depressing actions of 0.1 mM ALA were associated with increased cGMP-associated vasodilator-stimulated phosphoprotein (VASP) phosphorylation and increased sGC activity in homogenates of BPA cultured with ALA. Increasing iron availability with 0.1 mM FeSO 4 inhibited the decrease in contraction to serotonin and increase in sGC activity caused by ALA, associated with decreased protoporphyrin IX and increased heme. Chelating endogenous iron with 0.1 mM deferoxamine increased the detection of protoporphyrin IX and force depressing activity of 10 M ALA. The inhibition of sGC activation with the heme oxidant 10 M 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ) attenuated the force depressing actions of an NO donor without altering the actions of ALA. Thus control of endogenous formation of protoporphyrin IX from ALA by the availability of iron is potentially a novel physiological mechanism of controlling vascular function through regulating the activity of sGC.guanosine 3Ј,5Ј-cyclic monophosphate; heme metabolism; iron; vasodilation THE REGULATION OF THE SOLUBLE FORM of guanylate cyclase (sGC) by nitric oxide (NO) has been extensively studied for its role in promoting relaxation in the pulmonary and systemic vasculature through increasing production of cGMP (2,12,23,33). The bovine pulmonary arteries (BPA) examined in this study show an endothelium-dependent relaxation to NO, which is mediated through the stimulation of sGC (17,18). NO relaxes BPA through stimulating sGC in a manner that is controlled by a thiol redox mechanism regulated by cytosolic NADPH and glutathione redox (25). Under hypoxia the mechanism of relaxation to NO appears to shift to a cGMPindependent mechanism stimulating calcium-reuptake by the sarco(endo)plasmic reticulum Ca 2ϩ -adenosinetriphosphatase (SERCA) pump (26). NO activates sGC by binding a ferrous heme group, which appears to be a cofactor that is normally bound to sGC when it is isolated from tissues (6, 9, 34). Early studies investigating how NO activate...