| 1. |
- Dreja, Karl, et al.
(author)
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Increased store-operated Ca2+ entry into contractile vascular smooth muscle following organ culture
- 2001
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In: Journal of Vascular Research. - : S. Karger AG. - 1423-0135 .- 1018-1172. ; 38:4, s. 324-331
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Journal article (peer-reviewed)abstract
- Ca2+ inflow via store-operated Ca2+ channels was investigated in rings of rat tail and basilar arteries kept in serum-free organ culture, which is known to preserve the contractility of the vascular smooth muscle. After culture for 3-4 days, Ca2+ release from intracellular stores in response to caffeine (20 mM) was augmented 2- to 4-fold. Following depletion of intracellular Ca2+ stores by caffeine and thapsigargin (10 microM), addition of Ca2+ (2.5 mM) caused an increase in the intracellular Ca2+ concentration which was 2-3 times greater in cultured than in freshly dissected rings, and was not affected by verapamil (10 microM). In contrast, L-type Ca2+ channel currents were decreased by 20% after culture. While freshly dissected rings developed no or very little force in response to the addition of Ca2+ after store depletion, cultured rings developed 42% (tail artery) and 60% (basilar artery) of the force of high-K+-induced contractions. These contractions in cultured vessels were insensitive to verapamil but could be completely relaxed by SKF-96365 (30 microM). Store depletion by caffeine increased the Mn2+ quench rate 3- to 4-fold in freshly dissected as well as cultured tail artery, while there was no increase in freshly dissected basilar artery, but a 3-fold increase in cultured basilar artery. Uptake of Ca2+ into intracellular stores was twice as rapid in cultured as in freshly dissected tail artery. This study shows that organ culture of vascular smooth muscle tissue causes changes in Ca2+ handling, resembling the pattern seen in dedifferentiating smooth muscle cells in culture, although contractile properties are maintained.
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| 2. |
- Fogelstrand, Per, 1971, et al.
(author)
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External collar inhibits balloon-induced intimal hyperplasia in rabbits.
- 2002
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In: Journal of vascular research. - 1018-1172. ; 39:4, s. 361-7
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Journal article (peer-reviewed)abstract
- Intimal hyperplasia is a common complication following vascular interventions. To understand the underlying pathophysiology, the focus has mainly been on the intima and media. The adventitia has been less investigated, although adventitial hyperplasia is seen together with intimal hyperplasia. If the adventitial response is an important part of the process, the adventitia might be a target to inhibit intimal hyperplasia. In the present study we investigated whether an external collar attenuating the adventitial thickness could inhibit a balloon-induced intimal hyperplasia. The common carotid artery was injured in rabbits (n = 6) with a 3-french balloon catheter. The mid portion of the injured artery was encircled with a silicone collar (diameter = 2.0 mm). After 14 days the balloon-induced neointima was reduced by 54 +/- 6.3% underneath the collar. The adventitial and medial thickenings were also attenuated (36 +/- 8.7 and 44 +/- 4.3%, respectively). This study demonstrates that intimal hyperplasia following balloon injury can be inhibited with an external collar. This supports the idea of the adventitia as a potential target to inhibit intimal hyperplasia.
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| 3. |
- Hansen-Schwartz, Jacob, et al.
(author)
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Endothelium-Dependent Relaxant Responses to Selective 5-HT(1B/1D) Receptor Agonists in the Isolated Middle Cerebral Artery of the Rat.
- 2003
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In: Journal of Vascular Research. - : S. Karger AG. - 1423-0135 .- 1018-1172. ; 40:6, s. 561-566
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Journal article (peer-reviewed)abstract
- The vasomotor effects of triptans in the middle cerebral artery (MCA) of rats were studied using the pressurised arteriography method and in vitro vessel baths. Using the arteriograph, MCAs from Sprague-Dawley rats were mounted on two glass micropipettes, pressurised to 85 mm Hg and luminally perfused. Luminally added 5- hydroxytryptamine (5-HT), sumatriptan and rizatriptan induced maximal dilatations of 22 ± 4, 10 ± 2 and 13 ± 5%, respectively, compared to the resting diameter. The relaxant effect of sumatriptan was blocked by the 5- HT<sub>1B/1D</sub> receptor selective antagonist GR 55562 (10<sup>–6</sup><i>M</i>). The use of N<sup>ω</sup>-nitro-<i>L</i>-arginine and charybdotoxin revealed that the dilatation involved both nitric oxide and endothelially derived hyperpolarising factor. Thus, the earlier demonstrated expression of 5-HT<sub>1B/1D</sub> immunoreactivity in the endothelium may well translate into a relaxant response to 5-HT and triptans. Using the vessel bath technique, MCA segments were mounted on two metal wires. The relaxant responses to sumatriptan could not be reproduced using this model; instead, weak contractile responses (6 ± 3% of submaximal contractile capacity) were observed. The difference in observations between the experimental models may be related to the maintenance of shear stress in the arteriograph.
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| 4. |
- Liang, Min, et al.
(author)
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Polyamine Synthesis Inhibition Attenuates Vascular Smooth Muscle Cell Migration.
- 2004
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In: Journal of Vascular Research. - : S. Karger AG. - 1423-0135 .- 1018-1172. ; 41:2, s. 141-147
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Journal article (peer-reviewed)abstract
- Vascular smooth muscle cell migration, occurring after intimal injury, is a substantial clinical problem in atherosclerosis and restenosis after stenting. Here we investigate the effects of polyamine synthesis inhibition on vascular smooth muscle cell migration after maximal and submaximal growth stimulation with PDGF-AB or FCS. Vascular smooth muscle cells were obtained from mouse aorta explants. These cells coexpressed smooth muscle alpha-actin, PDGFRalpha and PDGFRbeta as demonstrated by immunocytochemistry. Treatment with a high (100 ng/ ml) concentration of PDGF-AB stimulated DNA synthesis 6-fold and markedly elevated cell migration. PDGF-AB (100 ng/ml) increased cellular spermidine concentration 2-fold, but had no effect on spermine or putrescine levels. Treatment with the polyamine synthesis inhibitors CGP48664 (1 µM) and DFMO (5 mM) prevented the PDGF-AB-induced increase in spermidine and reduced spermine concentrations, but had no effect on PDGF-AB-stimulated DNA synthesis or cell migration. Cell migration after submaximal stimulation with either PDGF-AB (8 ng/ml) or FCS (8%) was, however, inhibited by the polyamine synthesis blockers. In summary, these data show that polyamine synthesis inhibition attenuates vascular smooth muscle cell migration under submaximal growth-stimulating conditions, suggesting that polyamines participate in regulation of cell migration and that treatment with polyamine synthesis inhibitors might reduce vascular smooth muscle cell migration after intimal injury.
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| 5. |
- Liuba, Petru, et al.
(author)
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Co-Infection with CHLAMYDIA PNEUMONIAE and HELICOBACTER PYLORI Results in Vascular Endothelial Dysfunction and Enhanced VCAM-1 Expression in ApoE-Knockout Mice.
- 2003
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In: Journal of Vascular Research. - : S. Karger AG. - 1423-0135 .- 1018-1172. ; 40:2, s. 115-122
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Journal article (peer-reviewed)abstract
- <i>Background:</i> Upregulation of proinflammatory endothelial cell adhesion molecules and decreased bioactivity of endothelial nitric oxide (NO) are important in the pathogenesis of atherosclerosis. We investigated the effects of co-infection with <i>Chlamydia pneumoniae</i> and <i>Helicobacter pylori </i>on these two events in apoE-KO mice. <i>Methods:</i> Thirty-two apoE-KO mice, 8 weeks old, were equally divided into 4 groups. The first 2 groups were infected with either <i>C. pneumoniae</i> or <i>H. pylori,</i> while the 3rd group was infected with both <i>C. pneumoniae</i> and <i>H. pylori</i>. Mice from the 4th group and 4 wild-type mice served as controls. Thoracic and abdominal aortas were harvested after 10 weeks, and staining for vascular cell adhesion molecule-1 (VCAM-1) and intracellular adhesion molecule-1 was analyzed by immunocytochemistry. The endothelial vasomotor responses of thoracic aortas to methacholine were studied in organ chambers in the absence and presence of <i>L</i>-NAME. The plasma levels of nitrate/nitrite were measured. <i>Results:</i> Staining for VCAM-1 was more intense at the branching sites of aortas from mice with co-infection than in mono-infected or noninfected apoE-KO mice. The relaxation responses to methacholine and the plasma levels of nitrate/nitrite were significantly less in the co-infected group than in the other groups (p < 0.05). <i>Conclusion:</i> Co-infection of apoE-KO mice with <i>C. pneumoniae</i> and <i>H. pylori</i> seems to be associated with impaired bioactivity of endothelial NO and increased expression of VCAM-1 at branching sites. The findings may suggest an additive interaction of these pathogens in atherogenesis.
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| 6. |
- Lovdahl, C, et al.
(author)
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The synthetic metalloproteinase inhibitor batimastat suppresses injury-induced phosphorylation of MAP kinase ERK1/ERK2 and phenotypic modification of arterial smooth muscle cells in vitro
- 2000
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In: Journal of vascular research. - : S. Karger AG. - 1018-1172 .- 1423-0135. ; 37:5, s. 345-354
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Journal article (peer-reviewed)abstract
- Smooth muscle cell (SMC) migration and proliferation are important events in the formation of intimal lesions associated with atherosclerosis and restenosis following balloon angioplasty. The extracellular matrix has important functions in modulating SMC structure and function, but less is known about the role of the matrix metalloproteinases (MMPs) and their endogenous tissue inhibitors. The present study investigates the effects of the synthetic MMP inhibitor batimastat (BB94) on vascular SMCs. As experimental model, rat aortic smooth muscle cells in primary and secondary cultures were employed. Electron microscopy was used to investigate the effects of BB94 on the overall phenotypic properties of the cells. Induction of DNA synthesis and migration was studied by thymidine autoradiography and counting of cells moving into an injured zone. Gelatin zymography was used for the detection of BB94-mediated inhibition of injury-induced MMP activity. Phosphorylation of the mitogen-activated protein kinases ERK1/ERK2, two potential mediators of the injury-induced activation of the cells, was measured by Western blotting. The results show that BB94 restrained the phenotypic modulation of vascular SMCs in primary cultures and suppressed injury-induced DNA synthesis and migration. Moreover, the upregulation of ERK1/ERK2 phosphorylation in injured secondary cultures and in cells treated with bFGF was markedly reduced by BB94, whereas TIMP-2 lacked a clear effect. Our data suggest that BB94 inhibits injury-induced activation of vascular SMCs by acting on MMPs as well as other targets.
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| 7. |
- Norrby, Klas, 1937
(author)
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Human apo-lactoferrin enhances angiogenesis mediated by vascular endothelial growth factor in vivo
- 2004
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In: J Vasc Res. - : S. Karger AG. - 1018-1172. ; 41:4, s. 293-304
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Journal article (peer-reviewed)abstract
- BACKGROUND: Lactoferrin, LF, a multifunctional iron- and heparin-binding protein, present in exocrine body secretions and leukocytes, is remarkably resistant to proteolysis. Ingested bovine iron-unsaturated LF, apo-bLF, suppresses VEGF-A-mediated angiogenesis in a previously described rat mesentery angiogenesis assay, possibly explaining, at least in part, its established anticancer effect in rats and mice. METHODS: Using the same experimental system, we have now studied the effect of (i) ingested human apo-LF, apo-hLF, on angiogenesis mediated by VEGF-A and bFGF, (ii) ingested human iron-saturated LF, holo-hLF, on VEGF-A-mediated angiogenesis and (iii) subcutaneous continuously infused apo-hLF on VEGF-A-mediated angiogenesis. RESULTS: Ingested holo-hLF did not affect VEGF-A-mediated angiogenesis. Ingested apo-hLF (from one and the same batch) significantly enhanced VEGF-A-mediated angiogenesis but did not affect bFGF-mediated angiogenesis. Moreover, subcutaneously infused apo-hLF also significantly stimulated VEGF-A-mediated angiogenesis. CONCLUSION: Taken together, the data suggest that apo-hLF exerts a specific proangiogenic effect in VEGF-A-mediated angiogenesis. Clearly, human and bovine apo-LF exert opposite effects on VEGF-A-induced angiogenesis. Differences in molecular features between human and bovine LFs of possible significance for the outcome are discussed. In hypoxia, compensatory collateral circulation is mediated primarily by VEGF-A. We hypothesize that systemically administered apo-hLF may promote collateral blood vessel formation at hypoxic sites in normal tissue, thus counteracting ischemia and infarction.
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| 8. |
- Persson, Johan, et al.
(author)
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Endogenous Nitric Oxide Reduces Microvascular Permeability and Tissue Oedema during Exercise in Cat Skeletal Muscle.
- 2003
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In: Journal of Vascular Research. - : S. Karger AG. - 1423-0135 .- 1018-1172. ; 40:6, s. 538-546
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Journal article (peer-reviewed)abstract
- Based on a proposed increase in the release of the vasodilators nitric oxide (NO) and prostacyclin during exercise, and the fact that these substances have vascular permeability-reducing properties, this study was designed to evaluate (1) possible effects of exercise on hydraulic permeability, (2) whether permeability and muscle swelling are reduced by an increased release of NO and prostacyclin during exercise and (3) whether NO and prostacyclin are involved in exercise hyperaemia. The study was performed on an autoperfused cat calf muscle preparation with ligated lymph vessels, and exercise was induced by somatomotor nerve stimulation. Change in microvascular hydraulic permeability was estimated by a capillary filtration coefficient (CFC) technique. We found that the marked muscle volume increase after the start of the exercise gradually decreased, reaching an isovolumetric state within 25 min where CFC had decreased by about 25% (p < 0.05). CFC recovered completely after exercise was stopped. The decrease in CFC was abolished during blockade of endogenous NO by the NO synthase inhibitor <i>L</i>-NAME, but was preserved during blockade of endogenous prostacyclin by tranylcypromine. The muscle volume increase during exercise was about 60% greater with <i>L</i>-NAME than during vehicle or tranylcypromine (p < 0.01). Neither <i>L</i>-NAME nor tranylcypromine had any effect on exercise hyperaemia. We conclude that microvascular hydraulic permeability is reduced during exercise, that this effect reduces exercise-induced muscle swelling, and that the effects are mediated via release of NO. NO and prostacyclin are not involved in exercise hyperaemia.
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| 9. |
- Rippe, Bengt, et al.
(author)
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Transendothelial transport: the vesicle controversy.
- 2002
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In: Journal of Vascular Research. - : S. Karger AG. - 1423-0135 .- 1018-1172. ; 39:5, s. 375-390
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Research review (peer-reviewed)abstract
- The relative contribution of transcytosis vs. large pore transport to the passage of macromolecules across microvascular endothelia has been a controversial issue for nearly half a century. To separate transcytosis from 'porous' transport, the transcytosis inhibitors N-ethylmaleimide (NEM) and filipin have been tested in in situ or ex vivo perfused organs with highly conflicting results. In continually weighed isolated perfused organs, where measurements of pre- and post-capillary resistances, capillary pressure and capillary filtration coefficients can be repeatedly performed, high doses of NEM and filipin increased the bulk transport of macromolecules from blood to tissue, despite producing vasoconstriction. By contrast, in in situ perfused organs, marked reductions in the tissue uptake of albumin tracer have been observed after NEM and filipin. When tissue cooling has been employed as a means of inhibiting (active) transcytosis, results have invariably shown a low cooling sensitivity of albumin transport, compatible with passive transendothelial passage of albumin. This observation is further strengthened by the commonly observed dependence of albumin transport upon the capillary pressure and the rate of transcapillary convection. For low-density lipoprotein (LDL), a cooling-sensitive, non-selective transport component has been discovered, which may be represented by filtration through paracellular gaps, lateral diffusion through transendothelial channels formed by fused vesicles, or by transcytosis. From a physiological standpoint there is little evidence supporting active transendothelial transport of most plasma macromolecules. This seems to be supported by studies on caveolin-1-deficient mice lacking plasmalemmal vesicles (caveolae), in which there are no obvious abnormalities in the transendothelial transport of albumin, immunoglobulins or lipoproteins. Nevertheless, specific transport in peripheral capillaries of several hormones and other specific substances, similar to that existing across the blood-brain barrier, still remains as a possibility.
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| 10. |
- Rosengren, Bert-Inge, et al.
(author)
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Transendothelial transport of low-density lipoprotein and albumin across the rat peritoneum in vivo: Effects of the transcytosis inhibitors NEM and filipin
- 2002
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In: Journal of Vascular Research. - : S. Karger AG. - 1423-0135 .- 1018-1172. ; 39:3, s. 230-237
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Journal article (peer-reviewed)abstract
- This study was performed to investigate the mechanisms responsible for the transport of albumin and low-density lipoprotein (LDL) across capillary walls in vivo. To separate transcytosis from passive, 'porous' transport, we tested the effects of the transcytosis inhibitors N-ethylmaleimide (NEM) and filipin given intraperitoneally on the peritoneal capillary clearance of LDL and albumin in anesthetized rats undergoing peritoneal dialysis. Radiolabeled human albumin or LDL was given intraarterially, and Cr-51-EDTA was infused intravenously. A 2-hour peritoneal dialysis dwell was performed using 16 ml of conventional 1.36% glucose-based dialysis fluid. The clearance of LDL and albumin to the dialysate and the peritoneal mass transfer coefficient for Cr-51-EDTA were assessed. Following intraperitoneal NEM incubations (0.5-5 mM), there were marked increases in the peritoneal transport of albumin and LDL for NEM doses exceeding 1 mM. For lower NEM doses, there were no reductions in clearance. Filipin incubations (0.24 ug/ml) did not affect the clearance of either macromolecule. In conclusion, neither NEM nor filipin caused reductions in albumin or LDL clearance across the peritoneal capillaries. The present data clearly show that NEM and filipin are unsuitable as transcytosis inhibitors in vivo. Copyright (C) 2002 S. Karger AG, Basel.
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