摘要:

Nitric oxide (NO) is an important bio-regulatory molecule in the nervous, immune and cardiovascular systems. NO is synthesized from one of the guanidino nitrogens of L-arginine by the enzyme nitric oxide synthase (NOS). To date, several isoforms of NOS have been purified and cloned. These proteins represent a novel family of mammalian enzymes that contain both heme and cytochrome P450 reductase domains. The three prototypical forms of NOS: neuronal, cytokine-inducible and endothelial NOS, are derived from separate genes and are regulated by diverse signaling pathways. The purposes of this review are to highlight recent advances in the enzymology and molecular biology of this important family of proteins and to examine how this information pertains to the regulation of NO production.

ISSN:1018-1172    

DOI:10.1159/000159039

出版商:S. Karger AG    

年代:1994

数据来源: Karger

摘要:

The ability of platelet-activating factor (PAF) receptor antagonists to protect rats from the cardiovascular collapse induced by large doses of endothelin 1 led us to examine the capacity of rat cultured vascular smooth muscle cells to produce PAF and also to evaluate its potential functional roles in this cell type. Adenosine triphosphate and the vasoactive peptides, endothelin 1, angiotensin II, and arginine vasopressin, each elicited an increase in the PAF level in extracts of rat cultured vascular smooth muscle cells as determined by bioassay. PAF was not detectable (above 20 fmol/mg protein) in the supernatants of these cells. The identity of the bioactivity as PAF was confirmed by GC/MS which indicated that more than 80% of the PAF was 1-O-hexadecyl-2-acetyl-3-sn-glyceryl-phosphorylcholine. Exogenous PAF (100 nM) elicited increases in intracellular calcium that were inhibited by WEB 2086 (10 µM). Endothelin 1, at a concentration which stimulated PAF synthesis, (1 nM), elicited increases in intracellular calcium levels that were not inhibited by WEB 2086 (10 µM). Thus, endogenous PAF is unlikely to be involved in the endothelin-1-induced calcium increases. Although WEB 2086 (3–100 µM) inhibited concentration dependently fetal calf serum (10% v/v) induced [3H]-thymidine incorporation, reaching a maximum effect at 30 µM of 40-50% reduction, in parallel experiments WEB 2086 had no effect on serum-induced increases in cell numbers. We conclude that PAF is produced and retained by cultured rat vascular smooth muscle and that it is unlikely to contribute to the signaling of increases in intracellular calcium or prolifer

ISSN:1018-1172    

DOI:10.1159/000159040

出版商:S. Karger AG    

年代:1994

数据来源: Karger

摘要:

Angioplasty inflicts damage to the arterial wall. We studied whether augmented medial smooth muscle cell necrosis leads to augmented intimal hyperplasia and thus aggravates restenosis. Sixty-three normal femoral arteries of New Zealand White rabbits were overstretched with an angioplasty balloon during either maximal vasoconstriction with phenylephrine (32 arteries) or maximal vasodilation with nitroprusside (31 arteries). After 3 days’ survival, medial necrosis was determined as percentage of cross-sectional medial area. In the 3 weeks’ survival group, intimal hyperplasia was quantified as its average thickness. The dilation ratios, i.e. balloon diameter divided by arterial diameter at the time of dilation, were significantly higher in the 3 days’ and 3 weeks’ vasoconstriction groups (VC groups), respectively: 1.96 ± 0.10 (mean ± SD) and 2.14 ± 0.08 in the VC groups versus 1.27 ± 0.03 and 1.32 ± 0.05, respectively, in the vasodilation groups (VD groups) (both p < 0.001). Medial necrosis was more extensive in the VC group (64 ± 5%) than in the VD group (23 ± 7%, p& < 0.001) and proportional to the dilation ratio (r = 0.69, p& < 0.01). Intimal hyperplasia, however, was equal in the VC (59 ± 8 µm) and VD (57 ± 6 µm, NS) groups and not dependent on dilation ratio (r = 0.10). Thus, extensive medial necrosis produced during balloon dilation in maximally vasoconstricted arteries did not lead to more intimal hyperplasia than when less medial necrosis was induced by balloon dilation d

ISSN:1018-1172    

DOI:10.1159/000159041

出版商:S. Karger AG    

年代:1994

数据来源: Karger

摘要:

Laminin, a major structural glycoprotein complex of basement membranes has been found to be modulated by angiotensin II in vitro and in vivo. In cultures of aortic organoids and vascular smooth muscle cells, expression of laminin was stimulated by exogenous vasoconstrictor peptide. Stimulation of laminin protein and mRNA expression was observed for both laminin B1/ B2-chains and an unknown laminin heavy chain. Compared with PYS-2 cells, a mouse teratocarcinoma cell line which constitutively expresses a 10-kb mRNA transcript for ‘classical’ laminin A-chain, cultured vascular smooth muscle cells (VSMC) did not express a corresponding mRNA. However, cultured VSMC were found to express laminin A-chain-related mRNAs of ≈1.8 kb and ≈3.8kb, respectively. The 1.8-kb species of transcript was expressed in a constitutive manner, whereas the 3.8-kb mRNA was found to be regulated by angiotensin II. Laminin complexes secreted by cultured cells contained a ≈300 kD heavy chain which did not immunoreact with immuno-reagents raised against either the classical laminin complex secreted by EHS tumor cells or the merosin heavy chain. The putative A-chain analogue possibly represents a new form of a tissue-specific laminin heavy chain, distinct from the A- and M-chains thus far described. Translation products encoded by the A-chain-related transcripts of cultured smooth muscle cells could not be specified using currently available antibodies. The putative protein(s) is speculated to contain the biological features of the N-terminus of the laminin A-chain, namely self-assembly and association with collage

ISSN:1018-1172    

DOI:10.1159/000159042

出版商:S. Karger AG    

年代:1994

数据来源: Karger

摘要:

Vascular injury, activation of the coagulation system and thrombosis are common initial events in the accelerated atherosclerotic process. The role of thrombin generated at the site of aortic injury in the subsequent neointimal proliferation was studied in rabbits (n = 16) 3 weeks after balloon catheter injury. In half of these animals, potent thrombin antagonists, r-hirudin and P-PACK, were administered to prevent acute thrombotic events. Compared to aortas with intact endothelium (n = 8), aortas de-endothelialised 21 days earlier showed neointimal hyperplasia as measured by the intimal/medial ratio (0.68 vs. 0.04, injured vs. normal aortas) and an increase in both total cholesterol (4.08 vs. 3.31 mg/g, p < 0.05) and lipid peroxide content (31.3 vs. 1.1 nmol/g; p < 0.001). Neointimal hyperplasia following endothelial denudation was inhibited in rabbits treated with thrombin-antagonists (0.27 vs. 0.68, treated vs. untreated, p = 0.012) and neither total cholesterol (3.48 mg/g) nor lipid peroxide content (1.5 nmol/g) differed significantly from that of intact arteries. By demonstrating a strong relationship between thrombin generation following de-endothelialisation and the progressive intimal proliferation, this study supports the hypothesis that thrombin is an important contributor to restenosis after vascular injury. The highly atherogenic lipid peroxidation seems to be linked to the early, thrombin-mediated events, as it was completely prevented by adequate thrombin antagonism.

ISSN:1018-1172    

DOI:10.1159/000319584

出版商:S. Karger AG    

年代:1994

数据来源: Karger

摘要:

Vascular endothelial cells are an established source of thrombospondin 1 (TSP1), a multifunctional extracellular matrix molecule. TSP1 appears to play an important role in modulating endothelial cell functions such as proliferation, migration, and capillary morphogenesis. In addition, TSP1 has recently been reported to potently inhibit angiogenesis both in vitro and in vivo. To better understand the mechanism underlying the antiangiogenic property of TSP1, endogenous TSP1 production was disrupted in bovine aortic endothelial cells (BAEC) by stable transfection with a vector expressing a TSP1 anti-sense RNA. Stable transfectants in which the antisense vector caused a decrease in TSP1 production were assayed for their ability to form capillarylike cords on gelled basement membrane matrix and for their responsiveness to the angiogenic/chemotactic mediator basic fibroblast growth factor. BAEC in which TSP1 production was disrupted exhibited a ten-fold increase over control BAEC in chemotactic activity to basic fibroblast growth factor and a twofold increase over control cells in the number of capillary-like cords that formed on gelled basement membrane matrix. Thus, the down-regulation of endogenous TSP1 appears to facilitate endothelial cell chemotaxis and capillary morphogenesis. These studies suggest that the modulation of TSP1 production is an important component of the angiogenic response, and support the idea that soluble TSP1 inhibits angiogenesis by interfering with endothelial cell chemotaxis and capillary formation.

ISSN:1018-1172    

DOI:10.1159/000319585

出版商:S. Karger AG    

年代:1994

数据来源: Karger

ISSN:1018-1172    

DOI:10.1159/000319586

出版商:S. Karger AG    

年代:1994

数据来源: Karger