ISSN:0009-7330    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Abstract—A neuronal isoform of nitric oxide synthase (nNOS) has recently been located to the cardiac sarcoplasmic reticulum (SR). Subcellular localization of a constitutive NOS in the proximity of an activating source of Ca2+suggests that cardiac nNOS-derived NO may regulate contraction by exerting a highly specific and localized action on ion channels/transporters involved in Ca2+cycling. To test this hypothesis, we have investigated myocardial Ca2+handling and contractility in nNOS knockout mice (nNOS−/−) and in control mice (C) after acute nNOS inhibition with 100 &mgr;mol/L L-VNIO. nNOS gene disruption or L-VNIO increased basal contraction both in left ventricular (LV) myocytes (steady-state cell shortening 10.3±0.6% in nNOS−/−versus 8.1±0.5% in C;P<0.05) and in vivo (LV ejection fraction 53.5±2.7 in nNOS−/−versus 44.9±1.5% in C;P<0.05). nNOS disruption increasedICadensity (in pA/pF, at 0 mV, −11.4±0.5 in nNOS−/−versus −9.1±0.5 in C;P<0.05) and prolonged the slow time constant of inactivation ofICaby 38% (P<0.05), leading to an increased Ca2+influx and a greater SR load in nNOS−/−myocytes (in pC/pF, 0.78±0.04 in nNOS−/−versus 0.64±0.03 in C;P<0.05). Consistent with these data, [Ca2+]itransient (indo-1) peak amplitude was greater in nNOS−/−myocytes (410/495 ratio 0.34±0.01 in nNOS−/−versus 0.31±0.01 in C;P<0.05). These findings have uncovered a novel mechanism by which intracellular Ca2+is regulated in LV myocytes and indicate that nNOS is an important determinant of basal contractility in the mammalian myocardium. The full text of this article is available at http://www.circresaha.org.

ISSN:0009-7330    

出版商:OVID    

年代:2003

数据来源: OVID

ISSN:0009-7330    

出版商:OVID    

年代:2003

数据来源: OVID

ISSN:0009-7330    

出版商:OVID    

年代:2003

数据来源: OVID

ISSN:0009-7330    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Abstract—Adenosine is released during tissue injury, ischemia and tumor growth, and promotes angiogenesis. Because mast cells accumulate in the proximity of new blood vessel development, we examined if they may contribute to adenosine-induced angiogenesis. We found that HMC-1 human mast cells express A2A, A2B, and A3adenosine receptors. The adenosine agonist NECA (100 &mgr;mol/L) increased interleukin-8 (IL-8), vascular endothelial growth factor (VEGF), and angiopoietin-2 mRNA expression. NECA-induced secretion of IL-8 and VEGF was verified by ELISA. A2Breceptors mediate VEGF and IL-8 secretion because neither CGS21680 (selective A2Aagonist) nor IB-MECA (selective A3agonist) produced this effect, and it was inhibited by the selective A2Bantagonist IPDX but not by the selective A2Aantagonist SCH58261 or the selective A3antagonist MRS1191. In contrast, the selective A3agonist IB-MECA (EC501 nmol/L) stimulated angiopoietin-2 expression. Conditioned media from NECA-activated HMC-1 stimulated human umbilical vein endothelial cell proliferation and migration, and induced capillary tube formation. Capillary formation induced by mast cell–conditioned media was maximal if both HMC-1 A2Band A3receptors were activated, whereas activation of A2Breceptor alone was less effective. Thus, adenosine A2Band A3receptors act in a functional cooperative fashion to promote angiogenesis by a paracrine mechanism involving the differential expression and secretion of angiogenic factors from human mast cells.

ISSN:0009-7330    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Abstract—During angiogenesis, microvascular endothelial cells (ECs) secrete proteinases that permit penetration of the vascular basement membrane as well as the interstitial extracellular matrix. This study tested the hypothesis that cathepsin S (Cat S) contributes to angiogenesis. Treatment of cultured ECs with inflammatory cytokines or angiogenic factors stimulated the expression of Cat S, whereas inhibition of Cat S activity reduced microtubule formation by impairing cell invasion. ECs from Cat S–deficient mice showed reduced collagenolytic activity and impaired invasion of collagens type I and IV. Cat S–deficient mice displayed defective microvessel development during wound repair. This abnormal angiogenesis occurred despite normal vascular endothelial growth factor and basic fibroblast growth factor levels, implying an essential role for extracellular matrix degradation by Cat S during microvessel formation. These results demonstrate a novel function of endothelium-derived Cat S in angiogenesis.

ISSN:0009-7330    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Abstract—Advanced pulmonary arterial hypertension is characterized by extensive vascular remodeling that is usually resistant to vasodilator therapy. Mevastatin is an inhibitor of 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase, the rate-limiting step for cholesterol synthesis. HMG-CoA reductase inhibitors have been shown to upregulate the cyclin-dependent kinase inhibitor p27Kip1and to block cell proliferation through cholesterol-independent pathways. The aim of this study was to determine the effect of mevastatin on DNA synthesis, cell cycle progression, and cell proliferation in rat pulmonary artery smooth muscle cells (PASMCs). We found that mevastatin induced G1arrest and decreased DNA synthesis in rat PASMCs and did so in association with an increase in both total and cyclin E-bound p27Kip1. This caused a marked decrease in cyclin E kinase activity, which suggests an important role for p27Kip1in the ability of mevastatin to induce G1arrest. However, in PASMCs lacking functional p27Kip1, mevastatin still decreased cyclin E kinase activity, caused G1arrest, and decreased DNA synthesis. In p27Kip1-deficient PASMCs, mevastatin induced a greater reduction of cyclin E protein levels (to 35% of control) than in wild-type cells (to 70% of control) and also reduced the phosphorylation of cdk2 on threonine 160. Mevastatin also caused apoptosis in both wild-type and p27Kip1-deficient PASMCs and was able to do so at a dose that did not induce cell cycle arrest. These data suggest that HMG-CoA reductase inhibitors can both inhibit cell proliferation and induce apoptosis in PASMCs through p27Kip1-independent pathways and may be important therapeutic agents in pulmonary arterial hypertension.

ISSN:0009-7330    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Abstract—We have previously demonstrated that urokinase-type plasminogen activator (uPA) is highly expressed in the aneurysmal segment of the abdominal aorta (AAA) in apolipoprotein E–deficient (apoE−/−) mice treated with angiotensin II (Ang II). In the present study, we tested the hypothesis that uPA is essential for AAA formation in this model. An osmotic minipump containing Ang II (1.44 mg/kg per day) was implanted subcutaneously into 7- to 11-month-old male mice for 1 month. Ang II induced AAA in 9 (90%) of 10 hyperlipidemic mice deficient in apoE (apoE−/−/uPA+/+mice) but in only 2 (22%) of 9 mice deficient in both apoE and uPA (apoE−/−/uPA−/−mice) (P<0.05). Although the expansion of the suprarenal aorta was significantly less in apoE−/−/uPA−/−mice than in apoE−/−/uPA+/+mice, the aortic diameters of the aorta immediately above or below the suprarenal aorta were similar between the 2 groups. Ang II induced AAA in 7 (39%) of 18 strain-matched wild-type C57 black/6J control mice. The incidence was significantly higher in atherosclerotic apoE-deficient (apoE−/−) mice, in which 8 (100%) of 8 mice developed AAA. Only 1 (4%) of 27 uPA−/−mice developed AAA after Ang II treatment. We conclude the following: (1) uPA plays an essential role in Ang II–induced AAA in mice with or without preexisting hyperlipidemia and atherosclerosis; (2) uPA deficiency does not affect the diameter of the nonaneurysmal portion of the aorta; and (3) atherosclerosis and/or hyperlipidemia promotes but is not essential for Ang II–induced AAA formation in this model.

ISSN:0009-7330    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Abstract—Long-chain fatty acids (FA) coordinately induce the expression of a panel of genes involved in cellular FA metabolism in cardiac muscle cells, thereby promoting their own metabolism. These effects are likely to be mediated by peroxisome proliferator-activated receptors (PPARs). Whereas the significance of PPAR&agr; in FA-mediated expression has been demonstrated, the role of the PPAR&bgr;/&dgr; and PPAR&ggr; isoforms in cardiac lipid metabolism is unknown. To explore the involvement of each of the PPAR isoforms, neonatal rat cardiomyocytes were exposed to FA or to ligands specific for either PPAR&agr; (Wy-14,643), PPAR&bgr;/&dgr; (L-165041, GW501516), or PPAR&ggr; (ciglitazone and rosiglitazone). Their effect on FA oxidation rate, expression of metabolic genes, and muscle-type carnitine palmitoyltransferase-1 (MCPT-1) promoter activity was determined. Consistent with the PPAR isoform expression pattern, the FA oxidation rate increased in cardiomyocytes exposed to PPAR&agr; and PPAR&bgr;/&dgr; ligands, but not to PPAR&ggr; ligands. Likewise, the FA-mediated expression of FA-handling proteins was mimicked by PPAR&agr; and PPAR&bgr;/&dgr;, but not by PPAR&ggr; ligands. As expected, in embryonic rat heart-derived H9c2 cells, which only express PPAR&bgr;/&dgr;, the FA-induced expression of genes was mimicked by the PPAR&bgr;/&dgr; ligand only, indicating that FA also act as ligands for the PPAR&bgr;/&dgr; isoform. In cardiomyocytes, MCPT-1 promoter activity was unresponsive to PPAR&ggr; ligands. However, addition of PPAR&agr; and PPAR&bgr;/&dgr; ligands dose-dependently induced promoter activity. Collectively, the present findings demonstrate that, next to PPAR&agr;, PPAR&bgr;/&dgr;, but not PPAR&ggr;, plays a prominent role in the regulation of cardiac lipid metabolism, thereby warranting further research into the role of PPAR&bgr;/&dgr; in cardiac disease.

ISSN:0009-7330    

出版商:OVID    

年代:2003

数据来源: OVID