ISSN:0009-7330    

出版商:OVID    

年代:2001

数据来源: OVID

ISSN:0009-7330    

出版商:OVID    

年代:2001

数据来源: OVID

ISSN:0009-7330    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

Prostaglandin H synthase (PGHS) is a rate-limiting enzyme in the production of prostaglandins and thromboxane, which are important regulators of vascular function. Under normal physiological conditions, PGHS-dependent vasodilators (such as prostacyclin) modulate vascular tone. However, PGHS-dependent vasoconstriction (mediated by thromboxane and/or its immediate precursor, PGH2) predominates in some vascular pathologies (eg, systemic hypertension, diabetes, cerebral ischemia, and aging). This review will discuss the role of PGHS-dependent modulation of vascular function in a number of vascular beds (systemic, pulmonary, cerebral, and uterine) with an emphasis on vascular pathophysiology. Moreover, the specific contributions of the different isoforms (PGHS-1 and PGHS-2) are discussed. Understanding the role of PGHS in vascular function is of particular importance because they are the targets of the commonly used nonsteroidal antiinflammatory drugs (NSAIDs), which include aspirin and ibuprofen. Importantly, with the advent of specific PGHS-2 inhibitors for treatment of conditions such as chronic inflammatory disease, it is an opportune time to review the data regarding PGHS-dependent modulation of vascular function.

ISSN:0009-7330    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

We recently reported that angiotensin II (Ang II) induced IL-6 mRNA expression in cardiac fibroblasts, which played an important role in Ang II–induced cardiac hypertrophy in paracrine fashion. The present study investigated the regulatory mechanism of Ang II–induced IL-6 gene expression, focusing especially on reactive oxygen species (ROS)-mediated signaling in cardiac fibroblasts. Ang II increased intracellular ROS in cardiac fibroblasts, and the increase was completely inhibited by the AT-1 blocker candesartan and the NADH/NADPH oxidase inhibitor diphenyleneiodonium (DPI). We first confirmed that antioxidantN-acetylcysteine, superoxide scavenger Tiron, and DPI suppressed Ang II–induced IL-6 expression. Because we observed that exogenous H2O2also increased IL-6 mRNA, the signaling pathways downstream of Ang II and exogenous H2O2were compared. Ang II, as well as exogenous H2O2, activated ERK, p38 MAPK, and JNK, which were significantly inhibited byN-acetylcysteine and DPI. In contrast with exogenous H2O2, however, Ang II did not influence phosphorylation and degradation of I&kgr;B-&agr;/&bgr; or nuclear translocation of p65, nor did it increase NF-&kgr;B promoter activity. PD98059 and SB203580 inhibited Ang II–induced IL-6 expression. Truncation and mutational analysis of the IL-6 gene promoter showed that CRE was an importantcis-element in Ang II–induced IL-6 gene expression. NF-&kgr;B–binding site was important for the basal expression of IL-6, but was not activated by Ang II. Ang II phosphorylated CREB through the ERK and p38 MAPK pathway in a ROS-sensitive manner. Collectively, these data indicated that Ang II stimulated ROS production via the AT1 receptor and NADH/NADPH oxidase, and that these ROS mediated activation of MAPKs, which culminated in IL-6 gene expression through a CRE-dependent, but not NF-&kgr;B–dependent, pathway in cardiac fibroblasts.

ISSN:0009-7330    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

Early growth response factor-1 (Egr-1) controls the expression of a growing number of genes involved in the pathogenesis of atherosclerosis and postangioplasty restenosis. Egr-1 is activated by diverse proatherogenic stimuli. As such, this transcription factor represents a key molecular target in efforts to control vascular lesion formation in humans. In this study, we have generated DNAzymes targeting specific sequences in human EGR-1 mRNA. These molecules cleave in vitro transcribed EGR-1 mRNA efficiently at preselected sites, inhibit EGR-1 protein expression in human aortic smooth muscle cells, block serum-inducible cell proliferation, and abrogate cellular regrowth after mechanical injury in vitro. These DNAzymes also selectively inhibit EGR-1 expression and proliferation of porcine arterial smooth muscle cells and reduce intimal thickening after stenting pig coronary arteries in vivo. These findings demonstrate that endoluminally delivered DNAzymes targeting EGR-1 may serve as inhibitors of in-stent restenosis.

ISSN:0009-7330    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

Recent studies have suggested a proangiogenic effect of angiotensin-converting enzyme (ACE) inhibition. We hypothesized that such a proangiogenic effect of ACE inhibition may be mediated, in part, by bradykinin (BK) B2-receptor pathway. This study therefore examined the neovascularization induced by ACE inhibitor treatment in B2receptor–deficient mice (B2−/−) in a model of surgically induced hindlimb ischemia. After artery femoral occlusion, wild-type and B2−/−mice were treated with or without ACE inhibitor (perindopril, 3 mg/kg/d) for 28 days. Angiogenesis was then quantitated by microangiography, capillary density measurement, and laser Doppler perfusion imaging. The protein levels of vascular endothelial growth factor (VEGF) and endothelial nitric oxide synthase (eNOS) were determined by Western blot. In wild-type animals, vessel density and capillary number in the ischemic leg were raised by 1.8- and 1.4-fold, respectively, in mice treated with ACE inhibitor when compared with the nontreated animals (P<0.01). This corresponded to an improved ischemic/nonischemic leg perfusion ratio by 1.5-fold in ACE inhibitor–treated animals when compared with the untreated ones (0.87±0.07 versus 0.59±0.05, respectively,P<0.01). Activation of the angiogenic process was also associated with a 1.7-fold increase in tissue eNOS protein level in mice treated with ACE inhibitor (P<0.05 versus control) but not with changes in VEGF protein level. Conversely, ACE inhibition did not affect vessel density, blood flow, and eNOS protein level in ischemic hindlimb of B2−/−mice. Therefore, proangiogenic effect of ACE inhibition is mediated by B2-receptor signaling and was associated with upregulation of eNOS content, independently of VEGF expression.

ISSN:0009-7330    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

Oxygen- and nitrogen-derived free radicals and oxidants play an important role in the pathogenesis of diabetic endothelial dysfunction. Recently we proposed the importance of oxidant-induced DNA strand breakage and activation of the nuclear enzyme poly(ADP-ribose) polymerase (PARP) in the pathogenesis of diabetic endothelial dysfunction. In this study, we tested whether established diabetic endothelial dysfunction is reversible by PARP inhibition. The novel PARP inhibitor PJ34 (10 mg/kg per day PO) was given at various lengths (4 weeks or 3 days) for established streptozotocin-diabetic animals. In addition, we also tested whether incubation of the aortic rings with PJ34 (3 &mgr;mol/L) or a variety of other PARP inhibitors for 1 hour affects the diabetic vascular changes. Both 4-week and 3-day PARP-inhibitor treatment of streptozotocin-diabetic mice with established endothelial dysfunction fully reversed the acetylcholine-induced endothelium-dependent relaxations in vitro. Furthermore, 1-hour in vitro incubation of aortae from streptozotocin-diabetic mice with various PARP inhibitors was able to reverse the endothelial dysfunction. ATP, NAD+, and NADPH levels were markedly reduced in diabetic animals, and PARP-inhibitor treatment was able to restore these alterations. Unexpectedly, pharmacological inhibition of PARP not only prevents the development of the endothelial dysfunction but is also able to rapidly reverse it. Thus, PARP activation and the associated metabolic compromise represent an ongoing process in diabetic blood vessels. Pharmacological inhibition of this process is able to reverse diabetic endothelial dysfunction.

ISSN:0009-7330    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

Heterodimeric class I phosphoinositide 3-kinase (PI3K) has been shown to be involved in the stimulation of voltage-gated Ca2+channels by various mediators. In this study, we bring evidences that vascular L-type Ca2+channels can be modulated by both tyrosine kinase–regulated class Ia and G protein–regulated class Ib PI3Ks. Purified recombinant PI3Ks increased the peak Ca2+channel current density when applied intracellularly. Furthermore, PI3K&agr;-, &bgr;-, and &dgr;-mediated stimulations of Ca2+channel currents were increased by preactivation by a phosphotyrosyl peptide, whereas PI3K&ggr;- and &bgr;-mediated effects were increased by G&bgr;&ggr;. In freshly isolated and cultured vascular myocytes, angiotensin II and G&bgr;&ggr; stimulated L-type Ca2+channel current. In contrast, platelet-derived growth factor (PDGF)-BB and the phosphotyrosyl peptide did not stimulate Ca2+channel current in freshly isolated cells despite the presence of endogenous PDGF receptors and PI3K&agr; and PI3K&ggr;. Interestingly, when endogenous PI3K&bgr; expression arose in cultured myocytes, both PDGF and phosphotyrosyl peptide stimulated Ca2+channels through PI3K&bgr;, as revealed by the inhibitory effect of an anti-PI3K&bgr; antibody. These results suggest that endogenous PI3K&bgr; but not PI3K&agr; is specifically involved in PDGF receptor–induced stimulation of Ca2+channels and that different isoforms of PI3K regulate physiological increases of Ca2+influx in vascular myocytes stimulated by vasoconstrictor or growth factor.

ISSN:0009-7330    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

Abstract—L-type calcium channels (Cav1.m) inactivate in response to elevation of intracellular Ca2+(Ca2+-dependent inactivation) and additionally by conformational changes induced by membrane depolarization (fast and slow voltage-dependent inactivation). Molecular determinants of inactivation play an essential role in channel inhibition by phenylalkylamines (PAAs). The relative impacts, however, of Ca2+-dependent and voltage-dependent inactivation in Cav1.2 sensitivity for PAAs remain unknown. In order to analyze the role of the different inactivation processes, we expressed Cav1.2 constructs composed of different &bgr;-subunits (&bgr;1a-, &bgr;2a-, or &bgr;3-subunit) in Xenopus oocytes and estimated their (-)gallopamil sensitivity by means of the two-microelectrode voltage clamp with either Ba2+or Ca2+as charge carrier. Cav1.2 consisting of the &bgr;2a-subunit displayed the slowest inactivation and the lowest apparent sensitivity for the PAA (-)gallopamil. A significantly higher apparent (-)gallopamil-sensitivity with Ca2+as charge carrier was observed for all 3 &bgr;-subunit compositions. The kinetics of Ca2+-dependent inactivation and slow voltage-dependent inactivation were not affected by drug. The higher sensitivity of the Cav1.2 channels for (-)gallopamil with Ca2+as charge carrier results from slower recovery (&tgr;rec,Ca≈15 seconds versus &tgr;rec,Ba≈3 to 5 seconds) from a PAA-induced channel conformation. We propose a model where (-)gallopamil promotes a fast voltage-dependent component in Cav1.2 inactivation. The model reproduces the higher drug sensitivity in Ca2+as well as the lower sensitivity of slowly inactivating Cav1.2 composed of the &bgr;2a-subunit.

ISSN:0009-7330    

出版商:OVID    

年代:2001

数据来源: OVID