Cartilage oligomeric matrix protein (thrombospondin-5) is expressed by human vascular smooth muscle cells. (41/445)

Cartilage oligomeric matrix protein (COMP/thrombospondin [TSP]-5) belongs to the thrombospondin gene family and is an extracellular glycoprotein found predominantly in cartilage and tendon. To date, there is limited evidence of COMP/TSP-5 expression outside of the skeletal system. The aim of the present study was to investigate the expression of COMP/TSP-5 in cultured human vascular smooth muscle cells and human arteries. COMP/TSP-5 mRNA and protein expression was detected in cultured human vascular smooth muscle cells with both Northern blotting and immunoprecipitation. Serum, as well as transforming growth factor (TGF)beta1 and TGF-beta3, stimulated COMP/TSP-5 mRNA expression. COMP/TSP-5 was detected in normal as well as atherosclerotic and restenotic human arteries with immunohistochemistry. The majority of COMP/TSP-5 was expressed in close proximity to vascular smooth muscle cells. In vitro attachment assays demonstrated strong adhesion of smooth muscle cells to COMP/TSP-5-coated surfaces, with the majority of cells spreading and forming stress fibers. In addition, COMP/TSP-5 supported the migration of smooth muscle cells in vitro. The present study shows that COMP/TSP-5 is present in human arteries and may play a role in the adhesion and migration of vascular smooth muscle cells during vasculogenesis and in vascular disease settings such as atherosclerosis.  (+info)

Nitric oxide-mediated modulation of the endothelin-1 signalling pathway in the human cardiovascular system. (42/445)

1. We studied the ability of nitric oxide (NO) to physiologically antagonize endothelin-1 (ET-1) induced constrictions in human internal mammary artery (IMA). We also investigated the hypothesis that NO interacts directly with ET-receptor binding in human heart and aorta. 2. ET-1 potently contracted IMA (EC(50) 6.86 nM, 95% CI: 3.5 - 13.4 nM; n=12). The constrictor response to 10 nM ET-1 was fully reversed by the NO-donor diethylamine NONOate (DEA/NO; EC(50) 2.0 microM, 95% CI: 0.8 - 4.8 microM; n=5). The guanylate cyclase inhibitor ODQ (100 microM) reduced the response to DEA/NO but did not abolish it (E(MAX) 50.9+/-8.5% in the presence of ODQ; 113.0+/-8.4%, control). 3. The increase in cyclic GMP by 30 microM DEA/NO was abolished in the presence of 100 microM ODQ (n=6). 4. In saturation binding experiments the NO-donor Diethyltriamine NONOate (DETA/NO; 1 mM) caused a 90% reduction in maximum binding of [(125)I]-ET-1 in human heart, without affecting the affinity. This reduction in binding was abolished by haemoglobin. Pre-incubating either the radiolabel or the tissue with NO-donors did not reduce binding. A similar effect was observed in aortic smooth muscle. 5. We have shown that DEA/NO is able to reverse ET-1-induced contractions in the human vasculature. The binding studies suggest a direct interaction between NO and the ET receptor or receptor-ligand complex in human ventricular and aortic tissue. NO is released continuously in vivo, thus this apparent modification of ET-receptor binding may provide an additional mechanism by which NO counter-balances the effects of ET.  (+info)

Rho-kinase inhibitors prevent agonist-induced vasospasm in human internal mammary artery. (43/445)

1. Vasospasm of arterial conduits used for coronary artery surgery is an important cause of graft failure and is likely to result partly from raised levels of vasoconstrictor substances such as thromboxane A(2) and endothelin-1. Our aim was to find pharmacological agents that could prevent agonist-induced vasospasm. 2. Isometric tension was recorded from discarded segments of human left internal mammary artery (LIMA). Submaximal contraction evoked by the thromboxane A(2) mimetic U46619 (10 nM) was not inhibited by a blocker of store- and receptor-operated Ca(2+) channels (30 microM SKF96365) in the presence of diltiazem. Furthermore, contractions to < or =1 nM U46619 were preserved when extracellular Ca(2+) was reduced from 2.5 mM to 60 nM. Thus, sustained U46619-evoked contraction occurred without Ca(2+) influx. 3., We hypothesized that contraction might occur via Rho-kinase-mediated Ca(2+)-sensitization of myofilaments. Inhibitors of Rho-kinase (Y27632 and HA1077) were profound relaxants. If contraction was pre-evoked by 10 nM U46619, Y27632 and HA1077 caused full relaxation with EC(50)s of 1.67+/-0.22 microM and 3.58+/-0.35 microM respectively. Y27632 was also effective if applied before U46619, but was less potent. 4. Y27632 abolished contraction evoked by endothelin-1 and significantly reduced resting tone in the absence of a vasoconstrictor. 5. Rho-kinase-mediated Ca(2+)-sensitization appears to be a major mechanism of vasoconstriction in human LIMA. Rho-kinase inhibitors may have an important role in preventing vasospasm in arterial grafts used for coronary artery surgery.  (+info)

Experimental evaluation of coronary collateral development. (44/445)

During the last decade, there has been great interest in the potential use of biologic agents and mechanical techniques to enhance myocardial collateral development. Available experimental methods to detect the effects of interventions designed to improve collateral function include assessment of vascular cell proliferation, quantification of vessel number and size, appraisal of myocardial perfusion, and evaluation of myocardial function. The purpose of this review is to discuss the various experimental approaches for the evaluation of coronary collateral development, highlighting the relative strengths and limitations of the commonly used animal models and methods of assessment.  (+info)

Reciprocal regulation of cGMP-mediated vasorelaxation by soluble and particulate guanylate cyclases. (45/445)

Nitric oxide (NO) and atrial natriuretic peptides (ANP) activate soluble (sGC) and particulate guanylate cyclase (pGC), respectively, and play important roles in the maintenance of cardiovascular homeostasis. However, little is known about potential interactions between these two cGMP-generating pathways. Here we demonstrate that sGC and pGC cooperatively regulate cGMP-mediated relaxation in human and murine vascular tissue. In human vessels, the potency of spermine-NONOate (SPER-NO) and ANP was increased after inhibition of endogenous NO synthesis and decreased by prior exposure to glyceryl trinitrate (GTN). Aortas from endothelial NO synthase (eNOS) knockout (KO) mice were more sensitive to ANP than tissues from wild-type (WT) animals. However, in aortas from WT mice, the potency of ANP was increased after pretreatment with NOS or sGC inhibitor. Vessels from eNOS KO animals were less sensitive to ANP after GTN pretreatment, an effect that was reversed in the presence of an sGC inhibitor. cGMP production in response to SPER-NO and ANP was significantly greater in vessels from eNOS KO animals compared with WT animals. This cooperative interaction between NO and ANP may have important implications for human pathophysiologies involving deficiency in either mediator and the clinical use of nitrovasodilators.  (+info)

Plexus between internal mammary graft and pulmonary vasculature after minimally invasive coronary surgery. (46/445)

We report a complication associated with minimally invasive direct coronary artery bypass grafting surgery The patient suffered a nonfatal anterior myocardial infarction 1 day after he underwent minimally invasive bypass grafting using the internal mammary artery. Two months later, coronary arteriography revealed a fistulous connection between the left internal mammary graft and the left pulmonary vasculature. To our knowledge, this particular complication has not been reported following minimally invasive coronary surgery.  (+info)

Effect of valsartan on angiotensin II-induced plasminogen activator inhibitor-1 biosynthesis in arterial smooth muscle cells. (47/445)

Previous studies have shown that angiotensin II stimulates the synthesis of plasminogen activator inhibitor-1 in cultured vascular cells, which suggests that activation of the renin-angiotensin system may impair fibrinolysis. We have investigated the effects of angiotensin II and of valsartan, a recently developed angiotensin II antagonist that is highly specific and selective for the angiotensin II subtype 1 receptor, on plasminogen activator inhibitor-1 secretion by smooth muscle cells isolated from rat and human vessels. Angiotensin II induced a time- and concentration-dependent increase of plasminogen activator inhibitor activity in supernatants of rat aortic cells, which reached a plateau after 6 hours of incubation with 100 nmol/L angiotensin II (2.4+/-0.6-fold over control value; P:<0.001). The angiotensin II-induced plasminogen activator inhibitor activity was inhibited, in a concentration-dependent manner, by valsartan with an IC(50) value of 21 nmol/L. Valsartan fully prevented the angiotensin II-induced increase in plasminogen activator inhibitor-1 protein and mRNA. Furthermore, angiotensin II doubled the secretion of plasminogen activator inhibitor-1 by smooth muscle cells obtained from human umbilical and internal mammary arteries, and valsartan fully prevented it. Angiotensin II did not affect the secretion of tissue plasminogen activator antigen by any of the cell systems tested. Thus, valsartan effectively inhibits angiotensin II-induced plasminogen activator inhibitor-1 secretion without affecting that of tissue plasminogen activator in arterial rat and human smooth muscle cells.  (+info)

Hypoxia induces heat shock protein expression in human coronary artery bypass grafts. (48/445)

OBJECTIVE: Heat shock proteins (HSPs) are molecular chaperones which are essential for cell survival. Heat shock and hypoxia markedly increase the expression of several HSPs in various tissues, i.e. heart. In our in vitro study, we investigated whether HSPs are inducible in human vessels which are used as coronary artery bypass grafts. METHODS: We used remnants of the saphenous vein and the internal mammary artery from 34 patients undergoing coronary artery bypass surgery. Each vessel was divided into segments, one for control conditions at 37 degrees C (5% CO(2)-95% air), the remaining ones for thermal (30 min at 42 degrees C) or hypoxic treatment (6 h oxygen deprivation with nitrogen). The expression of Hsp60, Hsp72 and Hsp73 was investigated by immunohistochemistry and Western-blot analysis. RESULTS: Compared to controls, segments of the saphenous vein undergoing heat treatment showed significantly increased expression of Hsp72 in the intima (P=0.035) and Hsp73 in the media (P=0.003). In the internal mammary artery, Hsp72 and Hsp73 were expressed in the intima at significantly higher levels (P=0.042 each). A 6 h oxygen deprivation with nitrogen resulted in elevated levels of Hsp60 (media: P=0.048), of Hsp72 (intima: P<0.001 and media: P=0.004) and of Hsp73 (intima: P=0.029) in the saphenous vein. In the internal mammary artery, Hsp73 expression was significantly enhanced (intima: P=0.048 and media: P=0.017). The results were confirmed by Western-blot analysis in representative veins. CONCLUSIONS: These findings demonstrate the common cellular defense mechanism of HSP expression in response to stress in coronary artery bypass grafts. Hypoxia and heat treatment strongly induce Hsp72 and Hsp73 expression in human coronary artery bypass grafts.  (+info)