摘要:

The role of nitric oxide (NO) in cerebral autoregulation is controversial. The purpose of this study was to compare the effects on the lower limit of the cortical cerebral autoregulation of the inhibition of NO synthesis by Nω-nitro-L-arginine (L-NNA) infusion to saline and phenylephrine in pentobarbital-anaesthetized rats. Variations of the cortical cerebral blood flow (CBF), the cortical cerebrovascular resistances, the mean arterial pressure and the lower limit of cerebral autoregulation were compared in three groups: a group pre-treated with L-NNA (n = 8), a group pretreated with saline (n = 8) and a group pretreated with phenylephrine (n = 5). The laser-Doppler flowmetry continuously measured CBF. Controlled haemorrhage was performed after the intravenous infusion of L-NNA, saline, or phenylephrine. The lower limit of cerebral autoregulation of each rat was computed by the least-squares method. The lower limit of cerebral autoregulation was significantly higher after L-NNA infusion (74 ± 5 mm Hg) than after saline (43 ± 3 mm Hg; p < 0.01) or phenylephrine infusions (52 ± 5 mm Hg; p < 0.05). In conclusion, the role of NO on the cerebral autoregulation has been controversial; our results confirm the hypothesis that NO exerts a significant role in maintaining the lower limit of cerebral autoregulation in pentobarbital-anaesthetized r

ISSN:0167-6865    

DOI:10.1159/000179186

出版商:S. Karger AG    

年代:1996

数据来源: Karger

摘要:

In a placebo-controlled trial skeletal muscle biopsies were taken proximal and distal to the site of arterial stenosis, before cross-clamp and 20 min following reperfusion, in 8 well-matched critical limb ischaemia patients undergoing femorodistal bypass. Capillary endothelial swelling – a sign of reperfusion injury – was assessed following infusion with iloprost, a prostacyclin analogue, the prolonged beneficial effect of which on vascular graft flow rates has been demonstrated previously. Electron microscopy and image analysis of calf capillaries confirmed that critical limb ischemia patients had endothelial cell swelling before bypass, and that cross-clamp ischaemia caused further endothelial swelling in the placebo group. Samples from muscles proximal to the site of the bypass showed similar changes, indicating that systemic capillary damage occurs in muscle remote from the area of ischaemia. Iloprost treatment prevented endothelial swelling and increased the mean capillary lumen cross-sectional area. Iloprost, therefore, has a potentially beneficial effect on capillary function by limiting reperfusion injury during femorodistal byp

ISSN:0167-6865    

DOI:10.1159/000179187

出版商:S. Karger AG    

年代:1996

数据来源: Karger

摘要:

The aim of this study was to investigate the effect of a moderate degree of hypoxia on coronary vascular permeability to various lipophobic solutes. Using the multiple indicator dilution method the permeability-surface area (PS) products were determined for 125I-albumin, 125I-insulin and 57Co-cyanocobalamin in perfused rat hearts (flow ≈10 ml·min-1 •g-1) either with well-oxygenated (pO2 ≈ 96 kPa) or hypoxic (pO2 ≈ 45 kPa) solutions. The PS products for albumin, insulin and cyanocobalamin during the well-oxygenated equilibration period were 0.20 ± 0.03, 0.29 ± 0.06 and 2.0 ± 0.3 ml·min-1.g-1 (mean ± SE), respectively, relative to 131I-n-globulin. The PS products for these solutes 15 min after the induction of hypoxia were 1.3 ± 0.3,0.8 ± 0.1 (p 0.05), respectively. In hearts perfused with well-oxygenated solution for 75 min, the PS products for these solutes remained stable throughout the period of the study. Electron-microscopic examination of hypoxic tissues showed the presence of endothelial gaps of approximately 1 µm which were underlined by an intact basal lamina. We conclude that a moderate degree of hypoxia produces a large increase in permeability of albumin and insulin but has no effect on the PS products for cyanocobalamin and that the endothelial gaps are the likely mechanism of the observed increas

ISSN:0167-6865    

DOI:10.1159/000179188

出版商:S. Karger AG    

年代:1996

数据来源: Karger

摘要:

Stimulators of angiogenesis hold potential in promoting the development of collateral circulation in ischaemic tissue and accelerating wound healing, but promote pathological vasoformation in angiogenesis-dependent diseases (solid tumours, atherosclerosis). The renin-angiotensin system is implicated in both beneficial angiogenesis and pathological vascular growth. We investigated the angiogenic activity of angiotensin II (All) in a sponge implant model in mice; this peptide enhanced angiogenesis, as well as glycosaminoglycan (GAG, chondroitin sulfate proteoglycan) and protein synthesis in sponge matrix in mice in a dose-dependent fashion. Extensive angiogenesis was achieved with All (1 µg), which gave no significant increase in wet weight and protein and only a small effect on GAG. In the implants treated with All (2 µg) no further increase in angiogenesis was observed, whereas a marked effect was shown in wet weight (326 ± 15 vs. 424 ± 27 mg), total protein (18 ± 1 vs. 25 ± 1 µg/ww) and GAG(98 ± 10 vs. 160 ± 13 ng/ww). The local blood flow has been determined by measuring the washout rate of 133Xe injected into the implants, correlated with histological evidence of vessel growth. This model of angiogenesis has allowed sequential studies of fibrovascular tissue infiltration simultaneously with histological and biochemical parameters of angi

ISSN:0167-6865    

DOI:10.1159/000179189

出版商:S. Karger AG    

年代:1996

数据来源: Karger

摘要:

Fibroblasts growth factors (FGFs) exhibit well-known angiogenic actions, but there is some controversy about whether they have vasoactive effects on blood vessels which might contribute to angiogenesis per se. To clarify this, changes in arteriolar diameter were recorded during observation by videomicroscopy of 3rd- and 4th (terminal)-order arterioles (resting diameters 22.5 ± 0.5 µm and 14.4 ± 0.3 µm, respectively) in the hamster cheek pouch in response to FGF application. Recombinant human bFGF (basic) and aFGF (acidic) were applied from micropipettes positioned 5-10 µm from the adventitial surface of vessels. Maximum vasodilator effects of adenosine (10-4M) applied in a similar way were also observed. Adenosine increased the diameters of 4th-order arterioles by 37.2 ± 3.8% and those of 3rd-order arterioles by 38.7 ± 2.7%. bFGF produced vasodilatation (threshold dose 0.1 ng ml-1) in both classes of arterioles, while aFGF produced dose-dependent constriction (threshold dose 0.01 ng ml-1). A maximal dilator effect in 4th-order arterioles was obtained with 100 ng ml-1 bFGF, when diameters reached 82.6 ± 2.4% of those with adenosine. Maximal constrictor effect (-48.2 ± 5.6% of resting diameter) occurred with a dose of 100 ng ml-1 aFGF. Vehicle alone (MOPS or bicarbonate buffer used as solvents for FGFs) had no effect. As vasoconstrictors are known to stimulate growth of smooth muscle cells while dilators stimulate growth of endothelial cells, it is possible that the opposing vasoactivities demonstrated for aFGF and bFGF are linked with their selective mitogenicity for smooth muscle and endothelial cells, respectively, and contribute to their angiogenic

ISSN:0167-6865    

DOI:10.1159/000179190

出版商:S. Karger AG    

年代:1996

数据来源: Karger

摘要:

The aim of the present study was to investigate skin microcirculation in patients with diabetes to see if any differences in microvascular reactivity could be found between a skin area with low (fingers) or high risk (toes) of complications. Twelve male patients with type 1 diabetes were investigated, the age was 34.7 ± 8.5 years, and diabetes duration 12.8 ± 7.7 years (mean ± SD). Twelve healthy male subjects served as controls. Capillary blood cell velocity (CBV) in the nailfolds of the great toe and left fourth finger was investigated with videophotometric capiUaroscopy, and total skin microcirculation with laser Doppler fluxmetry (LDF). CBV and LDF were studied during rest, and following a 1-min arterial occlusion at the proximal phalanx of the digit. Skin temperature was similar in patients and controls. The diabetic patients showed normal CBV and LDF values in skin microcirculation of the fingers, while a reduced (p < 0.01) CBV was found during reactive hyperemia in the toes. The ratio between CBV and LDF was decreased (p < 0.01), indicating a maldistribution of blood between skin capillaries and subpapillary vessels in the toes of diabetic patients. These disturbances may be of importance for the development of foot complications in diabetic patien

ISSN:0167-6865    

DOI:10.1159/000179191

出版商:S. Karger AG    

年代:1996

数据来源: Karger

摘要:

The goal of this study was to investigate the influence of medical compression stockings on venolymphatic drainage in phlebologically healthy test persons and patients with chronic venous insufficiency. Using this new method, the outflow of an intradermally injected sodium fluorescein solution can be densitrometrically determined over a period of 60 min. In an evaluation of the method carried out over 5 weeks with 4 test persons, the variation coefficient was 19.3%, indicating a sufficient reproducibility. Concerning the effect of below-knee stockings (ankle pressure 30 mm Hg) on venolymphatic drainage, improvements of around 200 (p < 0.0001) and 250% were recorded for 10 healthy test persons (mean age 29.0 ± 3.1 years) and 20 patients suffering from chronic venous insufficiency (classes 4 and 5; p < 0.001), respectively. The results lead us to conclude that (i) the method presented here enables a quantification of the venolymphatic drainage and (ii) that therapy with compression stockings, for both healthy test persons and patients suffering from chronic venous insufficiency, leads to a significant improvement of venolymphatic drainage

ISSN:0167-6865    

DOI:10.1159/000179192

出版商:S. Karger AG    

年代:1996

数据来源: Karger

ISSN:0167-6865    

DOI:10.1159/000179193

出版商:S. Karger AG    

年代:1996

数据来源: Karger

ISSN:0167-6865    

DOI:10.1159/000179194

出版商:S. Karger AG    

年代:1996

数据来源: Karger

ISSN:0167-6865    

DOI:10.1159/000179185

出版商:S. Karger AG    

年代:1996

数据来源: Karger