ISSN:0167-6865    

DOI:10.1159/000178198

出版商:S. Karger AG    

年代:1994

数据来源: Karger

ISSN:0167-6865    

DOI:10.1159/000178199

出版商:S. Karger AG    

年代:1994

数据来源: Karger

摘要:

Topological and geometrical characteristics of the anastomotic arteriolar network in cat sartorius muscle were studied. The vessels were dilated and filled with gelatin-ink solution and the muscle cleared with methylsalicylate. The analysis was done on 11 muscles and included 2297 vascular segments and 772 vascular loops classified according to their position within the network. On average, each muscle had 644 transverse arterioles arising from the anastomotic vessels. The length of vascular segments close to feeding arteries was greater than those located in the central region, while the number of transverse arterioles per unit length of arcade vessel showed an opposite tendency. Most vessel orders had similar diameters, except for the segments at the periphery of the muscle, which were significantly larger. No correlation was found between vessel length and diameter. Vascular loops located in the central part of the network were smaller, as assessed by area, perimeter, number of segments, segment length and number of branches. The variability of the parameters between muscles was smaller than variability within each muscle. We concluded that, in addition to the parameters previously reported, quantitative descriptions of anastomotic networks may be enhanced by considering certain topological aspects of microvessels. The separation of segments and loops according to the position in the network may reveal differences between muscles of different sizes and functions which would not be detected if the vessels were considered as a single group.

ISSN:0167-6865    

DOI:10.1159/000178200

出版商:S. Karger AG    

年代:1994

数据来源: Karger

摘要:

Using intravital microscopy of the rat cremaster muscle, we studied the effects of changing red blood cell (RBC) aggregation on RBC arteriolar velocity and perfused capillary density (PCD). To modify RBC aggregation, 2 and/or 10% dextran (molecular weights 40,000, 70,000 or 480,000) or fresh rat plasma was infused into adult male rats via a normovolemic hemodilution procedure. The high-molecular-weight dextrans (70,000 and 480,000) both induced RBC hyperaggregation associated with similar dose-dependent decreases in RBC arteriolar velocity (30 and 40% for dextran concentrations of 2 and 10%, respectively) and in PCD (35 and 37%, respectively, for the two concentrations). Conversely, with 40,000 molecular weight dextran or plasma, we observed a 30% increase in RBC arteriolar velocity, but no change in PCD or hyperaggregation. Intravenous injection of the antiaggregating drug troxerutin (10-3M), either before or after 2% dextran 70,000, significantly inhibited the effects of this dextran on RBC arteriolar velocity and on PCD. We conclude that RBC hyperaggregation can lead to changes in both arteriolar velocity and PCD and may, therefore, impair tissue oxygenation.

ISSN:0167-6865    

DOI:10.1159/000178201

出版商:S. Karger AG    

年代:1994

数据来源: Karger

摘要:

Sepsis is associated with alterations in microcirculatory flow which is demonstrated by impaired (O2 delivery and extraction by the peripheral tissues. Leukotrienes, derivatives of arachidonic acid, have been implicated as mediators of the septic process. We investigated the effect of diethylcarbamazine (DEC), a leukotriene inhibitor, on the flow of endotoxin-treated blood through a 5-micron pore polycarbonate filter and on survival in a model of intraperitoneal rat endotoxemia. Endotoxin alone significantly impaired red blood cell flow through the filter. This effect was reversed with DEC treatment. In addition, treatment with DEC significantly reduced rat endotoxemia mortality. This study indicates that impaired red cell deformability may be one factor involved in the alterations in microcirculatory flow following sepsis. Leukotriene inhibition, with DEC improves red cell deformability in vitro, and may account, in part, for the improved survival seen in rat endotoxemia.

ISSN:0167-6865    

DOI:10.1159/000178202

出版商:S. Karger AG    

年代:1994

数据来源: Karger

摘要:

Reperfusion injury is responsible for the failure of up to 15% of otherwise successful lower limb bypass procedures for critical limb ischaemia. It is also responsible for complications in myocardial revascularisation, organ transplantation and free flap transfers. The majority of experimental work investigating reperfusion injury has studied acute ischaemia in normal tissues which may reflect the situation in organ transplantation and free flap transfers, but in vascular reconstructive surgery the distal limb circulation is severely compromised prior to surgery. In the present study a model of chronic ischaemia in the rat hind limb has been produced by ligation of the left common iliac artery. Femoral artery blood pressure and flow measurements showed a mean reduction to 53% and 41% respectively when compared to the contralateral limb. These changes were maintained for up to nine weeks following ligation of the common iliac artery. Contrast arteriography was used to establish the anatomy of the collaterals and demonstrated that the femoral artery is an end artery. This technique provides a model of experimental chronic ischaemia which is stable for up to nine weeks and may be used to investigate the mechanisms involved in the reperfusion injury.

ISSN:0167-6865    

DOI:10.1159/000178203

出版商:S. Karger AG    

年代:1994

数据来源: Karger

摘要:

TMo date, capillary microscopy, transcutaneous oximetry (tcpO2) and laser Doppler fluxmetry are frequently used in the investigation of skin microcirculation in patients with lower limb ischaemia. The concomitant microcirculatory disturbances may be useful in addition to macrocirculatory parameters to discriminate the different degrees of ischaemic severity. The best ways of application of these methods and the choice of the best parameters to assess ischaemia have been insufficiently investigated. Therefore, skin microcirculation was investigated with the use of these techniques in 130 patients with different stages of lower limb ischaemia, divided according to their ankle-to-brachial pressure index (ABI). Patients were investigated in the sitting and the supine position. Measurements were performed at rest and during reactive hyperaemia following arterial occlusion, and before and after local skin heating. The reactive hyperaemic response using laser Doppler fluxmetry differed in every patient group investigated. Capillary red blood cell velocity was markedly impaired in critically ischaemic patients (ABI < 25%). Transcutaneous oxygen pressure measurements at rest rendered the highest positive predictive value (PV; 87%) to classify patients as having clinically severe ischaemia (Fontaine 3 or 4). Ankle and toe pressure measurements provided a PV value of 78%. Microcirculatory parameters and techniques appear to be useful as an addition to standard macrocirculatory techniques to assess the severity of lower limb ischaemia. This is particularly of importance in patients in whom macrocirculatory parameters are unattainable.

ISSN:0167-6865    

DOI:10.1159/000178204

出版商:S. Karger AG    

年代:1994

数据来源: Karger

摘要:

The endothelial cell (EC) response during the first 2 h after traumatic hemorrhagic shock (THS) was analyzed in the rat mesentery by electron microscopy. Using a computer-assisted image analysis system, we interactively measured THS-induced changes of the area and the mean height of EC as well as the number of swollen EC occluding the capillary lumen. Analysis distinguished between capillaries presenting with the lumen blocked by corpuscular blood cells and capillaries with an open lumen. THS resulted in a significant increase in EC height of capillaries with an open lumen, but not of capillaries with lumen blocked by blood cells when compared with the control group (p < 0.05). This phenomenon was found to be most prominent 60 min after THS. In addition, THS was accompanied by a significantly increased number of swollen EC which occluded capillaries with an open lumen. From these results we conclude that swelling of EC contributes to THS-induced microvascular injury. Occlusion of the capillary lumen by EC swelling may be regarded as the morphological correlate of the THS-induced ‘no-reflow’ phenome

ISSN:0167-6865    

DOI:10.1159/000178205

出版商:S. Karger AG    

年代:1994

数据来源: Karger

摘要:

The effect of a clinically used purified micronized flavonoid fraction (90% diosmin and 10% hesperidin) on leukocyte-endothelial cell interaction during ischemia-reperfusion injury was studied in the microcirculation of unanesthetized hamsters fitted with a skin fold window chamber. The drug was given orally in suspension with arabic gum (30 mg/kg) 8 h prior to induction of 4-hour tourniquet ischemia in the chamber window. Leukocyte-endothelial cell interaction was observed using fluorescence intravital microscopy in postcapillary venules (15-70 μm in diameter) at control and during reperfusion at 30 min and 2 and 24 h. Leukocytes were classified according to their flow pattern as (1) ‘passers’, including ‘free flowing’ leukocytes and those which were ‘flowing with endothelial contact’, and (2) ‘immobilized’ leukocytes. Untreated animals exhibited a significant increase of ‘immobilized’ leukocytes and of those ‘flowing with endothelial contact’ during reperfusion. Flavonoid-treated animals displayed a statistically significant lower number of’immobilized’ leukocytes at all time points during reperfusion. There was no change in the number of leukocytes ‘flowing with endothelial contact’ relative to the untreated animals. Since firm leukocyte attachment to the endothelial wall and subsequent emigration of leukocytes into the interstitium is a mechanism for tissue damage during inflammation, attenuation of this phenomenon during conditions of ischemia-reperfusion can in part explain previous observations that this purified micronized flavonoid fr

ISSN:0167-6865    

DOI:10.1159/000178206

出版商:S. Karger AG    

年代:1994

数据来源: Karger

摘要:

Hyaluronan is a structural component of the interstitial matrix in skin and is catabolized locally in skin as well as by lymphatic removal and subsequent degradation in lymph nodes and liver. The present experiments were designed to evaluate the role of interstitial fluid flux in turnover of hyaluronan in skin by measuring the maximal lymphatic flux of hyaluronan. Lymph flow, total protein concentration, hyaluronan concentration, and flux were measured every 15 min in prenodal lymph from the hind paw in 12 pentobarbital-anesthetized mongrel dogs at normal and increased interstitial fluid flux. An intravenous saline load (15% of body weight during the course of 30 min) was followed by a one-step increase in local venous pressure 30 min later (to a maximum of 50 mm Hg) and maintained at this level for the next 240 min. Lymph flow and hyaluronan concentration during the control period averaged 25.6 ± (SD) 23.2 (range 4.7-61.9) μl/min and 8.6 ± 2.8 (range 2.0-11.6) μg/ml, respectively. The hyaluronan concentration fell by 30% during the experimental period, while the lymph flow increased up to ten times above control. Total tissue water increased from 1.73 ± 0.11 ml/g dry weight during the control period to 1.91 ± 0.12 ml/g dry weight at the end of the experiment (p 0.05). The average lymphatic hyaluronan flux was 8.4 ± 5.4μg/h during the control period, peaked at about 60 μg/h, and averaged 33.6 ± 13.9 μg/h during the last hour of the experimental period. The total amount of hyaluronan drained from the paw during the 5-hour experimental period averaged 182 ± 137 (range 39-525) μg and corresponds to the normal daily lymphatic output of hyaluronan. Thus, the hyaluronan flux in lymph increases with increasing lymph flow and is maintained over a period of several hours, affecting hyaluronan tu

ISSN:0167-6865    

DOI:10.1159/000178207

出版商:S. Karger AG    

年代:1994

数据来源: Karger