摘要:

The aim of the study was to investigate the potential role of nitric oxide (NO) on the microcirculation in experimental acute pancreatitis in rats. Twenty-five rats were divided into the following groups: group A (5 rats) = control; group B (5 rats) = acute pancreatitis induced by retrograde taurocholate infusion into the pancreatobiliary duct without treatment; group C (5 rats) = acute pancreatitis treated with the NO donor L -arginine; group D (5 rats) = acute pancreatitis treated with the NO synthase inhibitor N-nitro- L -arginine (L-NNA); group E (5 rats) = without pancreatitis receiving L -NNA. The animals were observed throughout 4 h. The microcirculatory values of the pancreas, liver, colon, stomach and kidney were measured by means of laser Doppler flowmetry. Three animals of group D died after the third hour of the experiment. In rats with pancreatitis, a rapid decrease in microcirculatory values was observed. The most pronounced drop in capillary blood flow within all the organs was observed in rats treated with the NO synthase inhibitor L -NNA, L -arginine administration in rats with acute pancreatitis slightly improved the microcirculatory values, although the improvement was significant in colon perfusion only. We conclude that NO may have a beneficial influence on the capillary organ perfusion in acute pancreatitis. The administration of an NO synthase inhibitor seems to have a detrimental effect on acute pancreatitis.

ISSN:0167-6865    

DOI:10.1159/000179177

出版商:S. Karger AG    

年代:1996

数据来源: Karger

摘要:

The ability of relaxin (RLX), which is a potent microcirculatory effector in many species including the rat, to induce de novo angiogenesis in vascularized mammalian tissue was tested using the rat mesenteric-window angiogenesis assay. RLX was administered intraperitoneally on days 1-5 at doses of 0.33, 3.3 and 33 nM. Controls received the vehicle by the same route. Groups of animals were sacrificed at the end of the 1st, 2nd and 3rd weeks. Using computer-aided microscopic morphometry including image analysis, the response was quantified by sensitive, technically independent, highly reproducible methods in terms of the vascularized area (VA), a measure of microvascular spatial extension, and the microvascular length (MVL), a measure of microvascular density. The total MVL was computed from VA × MVL. The results obtained show that RLX did not cause significant changes in any of the variables tested, regardless of dose and observation time. These findings indicate that RLX is apparently unable to mediate significant de novo angiogenesis in the system used in contrast to previously tested angiogens such as basic fibroblast growth factor, vascular endothelial growth factor, isoform 165, and tumor necrosis factor-α. In previous studies, RLX has been shown to exert antitumor activity on breast cancer cells in vitro. In the search for a possible role for RLX as an anticancer agent in vivo, it is important to know that this peptide is not angiogenic, since de novo angiogenesis is known to be a prerequisite for tumor growth and metastatic sprea

ISSN:0167-6865    

DOI:10.1159/000179178

出版商:S. Karger AG    

年代:1996

数据来源: Karger

摘要:

To better understand normal microvascular network growth, we conducted a longitudinal study on the spinotrapezius muscle of Sprague-Dawley rats of 3 ages: weanling (3-4 weeks), juvenile (7-8 weeks) and mature (11-12 weeks). Morphometric analysis revealed that despite dramatic growth of the muscle (from 117 ± 60 mg in weanling to 417 ± 112 mg in mature rats), there is no significant change in the total number of arcade arteriole segments per network over this period (from 140 ± 35 to 181 ± 51). The mean arcade segment length increased over this period (from 0.96 ± 0.17 to 1.45 ± 0.32 mm), but not in proportion to tissue growth. Consequently, the total arcade segment length per unit muscle volume significantly decreased (from 1.36 ± 0.48 to 0.66 ± 0.12 mm/mm3). The estimated number of transverse arteriolar trees per muscle (approximately 600) did not appreciably change with growth, leading to a decrease in the number of trees per millimeter arcade arteriole (from 4.4 ± 1.2 to 2.3 ± 0.6). Transverse arteriolar trees underwent age-dependent increases in the number of segments within each branch order and in mean segment length. These observations suggest that arteriolar network growth during juvenile maturation occurs by elongation of pre-existing arcade and transverse vessels with angiogenesis occurring in the distal segments of transverse arterio

ISSN:0167-6865    

DOI:10.1159/000179179

出版商:S. Karger AG    

年代:1996

数据来源: Karger

摘要:

The long-term behavior of an arterial autograft was studied with special attention to the evolution of intimal hyperplasia. An arterial autograft measuring approximately 5 mm in length was implanted in the right common iliac artery of female Sprague-Dawley rats. Animals were sacrificed at 90, 120, 150, 180, 240, 360, 400, 540 and 730 days after implantation. Grafts were evaluated by optical microscopy, electron microscopy, and morphometry. Myointimal cells were marked using an antiactin monoclonal antibody and studied by transmission electron microscopy. In the long term, the myointima of the arterial wall appeared as a consolidated layer formed by smooth muscle cells of contractile phenotype, abundant extracellular material consisting of clumps of elastin and collagen fibers. Cell maturity and degree of differentiation were demonstrated by the incorporation of antiactin antibody. The medial layer of the grafted segment suffered a marked long-term loss of cells and became an acellular layer sustained by the elastic layers. The adventitial layer was markedly cellular and had abundant vasa vasorum. Morphometry showed that the myointimal layer in the operated territory was not uniform and consisted of tongues of varying thickness. The total thickness of the arterial wall did not differ significantly (p > 0.05) between the graft and the proximal and distal areas. The results suggest that the intimal hyperplasia originating during the repair process could assume some functions of the degenerated medial layer, maintaining long-term vascular homeostasis.

ISSN:0167-6865    

DOI:10.1159/000179180

出版商:S. Karger AG    

年代:1996

数据来源: Karger

摘要:

Objective: This study was conducted to examine the effects of endothelin (ET)-1 and ET-3 on hepatic venules and sinusoids and to identify the subtypes of ET receptors. Method: Hepatic venules and sinusoids of anesthetized mice were observed at the edge of the liver. ET-1, ET-3 and sarafotoxin (S6c, a selective ETB receptor agonist) were applied topically over the microvasculature. Results: ET-1, ET-3 and S6c (1-100 µM, 30 µl) induced dose-dependent vasoconstriction of the portal venules, the sinusoids and the central venules. The ETs and S6c were equipotent for these microvessels. BQ-123 (a selective ETA receptor antagonist) inhibited the constrictive effects of ET-3 (not of ET-1) on the portal venules and central venules, whereas it had no inhibitory effect on the sinusoids. Conclusions: In mouse hepatic venules and sinusoids, the vasoconstriction induced by ET-1 and ET-3 was mediated mainly through the ETB receptor subtype and partly through an unknown BQ-123-sensitive ET receptor subtype in the portal and central venules, and only through the ETB receptor subtype in the sinusoid

ISSN:0167-6865    

DOI:10.1159/000179181

出版商:S. Karger AG    

年代:1996

数据来源: Karger

摘要:

Microangiopathy of the skin has been recognized as an important factor in the development of skin diseases connected with chronic venous insufficiency (CVI). Here the relationship between postcapillary transmural pressure and precapillary vaso-constriction – we call it the postural feedback system – was examined in venous ulcers (n = 12) and compared to blood flow regulation in the inner ankle area of healthy controls (n = 12). Blood flow changes were measured by laser Doppler fluxmetry. Changes in the laser Doppler flux (LDF) minus the biological zero value were measured after 3 min of arterial occlusion, during 3 min of venous occlusion, while the leg was elevated and while it was lowered and expressed relative to the pretest resting value. In venous ulcers the LDF remained nearly unchanged after arterial occlusion (3 vs. 190%, p < 0.001), leg elevation caused an LDF decrease contrary to what was seen in the controls (-17 vs. +80%, p < 0.001), in the lowered leg an LDF decrease was found (-51 vs. -65%) and venous occlusion led to a profound reduction of flux (-78 vs. -84%). In severe CVI the precapillary arterioles seem to be dilated even with the leg at heart level. This finding means that the postural feedback system under resting conditions is upregulated, and ‘luxus’ hyperperfusion results. The upregulated postural feedback system contributes to the cutaneous microangiopathy due to chronic venous con

ISSN:0167-6865    

DOI:10.1159/000179182

出版商:S. Karger AG    

年代:1996

数据来源: Karger

摘要:

Voluntary hyperventilation (HV) provokes hemoconcentration due to a loss of fluid from the intravascular space. In 10 healthy male volunteers the hypothesis was tested whether HV increases transcapillary fluid shift into the interstitial compartment. For this purpose, fluorescent light intensity (FLI) alterations after intravenous injection of sodium fluorescein (Na fluorescein) before and during 3 min of HV were determined. Concomitantly, temperature and microvascular skin flux (laser Doppler fluxmetry, LDF) were recorded continuously. Hematocrit and serum proteins, as markers of hemoconcentration, increased significantly from 41.2 ± 2.3 to 42.7 ± 2.0% (p = 0.0023) and from 69.5 ± 3.4 to 72.9 ± 3.0 g/l (p = 0.0005, respectively). Skin temperature and LDF showed no changes during HV compared to baseline levels. Interstitial FLI indicating transcapillary diffusion of Na fluorescein was significantly higher (p < 0.001) during HV compared to the values recorded during the baseline period. The exact mechanism of enhanced transcapillary diffusion of Na fluorescein is not known. The distinct increase in FLI without a significant change in microvascular skin flux suggests an HV-induced increase in capillary pressure or an enhancement in capillary permeability for water and small solu

ISSN:0167-6865    

DOI:10.1159/000179183

出版商:S. Karger AG    

年代:1996

数据来源: Karger

摘要:

The spatial pattern of capillaries is one of many factors important for the optimisation of oxygen and nutrient delivery in a specified region of tissue. One area of particular interest to the vascular specialist is the skin of the dor-sum of the foot and toes, as these are especially prone to ulceration in patients with arterial disease. The aim of this study was therefore to establish the extent of capillary density (CD) heterogeneity in the normal skin of the dorsum of the foot and toes, since any great non-uniformity might produce regions of low perfusion, which may become vulnerable to ulceration. Using white-light (native) videomicroscopy at a magnification of × 40 in 15 healthy subjects (mean age 72 years), the dorsum of the foot and toes was systematically mapped by determining the CD at each of 25 sites on the dorsum of the foot, and at 2 sites on the distal phalanx of each toe. Off-line analysis of videoprints was then undertaken to determine CD at each site, according to a fixed protocol of measurement and data analysis. The mean value and spatial coefficent of variation of CD was then calculated for each foot. There was striking spatial heterogeneity of CD in the dorsum of the foot, some areas having low numbers of capillaries and other areas in the same foot having higher capillary numbers. This spatial heterogeneity of CD was observed in all the feet studied, and the mean coefficient of variability was 22.3%. The toes had a significantly higher mean CD (47.7/mm2) than the dorsum of the foot (33.5/mm2, p < 0.001). The finding of a significant spatial heterogeneity of CD in the foot of normal subjects has important implications in relation to function, methodology of CD measurement and the possibility that regional ‘rarefaction’ of CD may contribute to the pathogenesis of skin ulceration in arterial dis

ISSN:0167-6865    

DOI:10.1159/000179184

出版商:S. Karger AG    

年代:1996

数据来源: Karger