Effects of buflomedil and pentoxifylline on hamster skin-flap microcirculation: prediction of flap viability using orthogonal polarization spectral imaging

OBJECTIVE

This study investigated the effects of buflomedil and pentoxifylline, both of which are used in reconstructive surgery of hamster skin flap microcirculation, and evaluated the skin flap survival rate by orthogonal polarization spectral imaging.

METHOD

Twenty-four adult male Syrian golden hamsters were divided into three groups: a control (C, 0.1 ml 0.9% saline), buflomedil (B, 3 mg/kg/day), and pentoxifylline group (P, 14.5 mg/kg/day). Treatments administered intraperitoneally were initiated 1 hour before skin flap preparation and continued for 7 days post-operatively at 12-hour intervals. Preparations (skin flaps) were divided into 12 fields, which were organized into six bands. Functional capillary density (FCD, in mm/mm(2)), distance from the skin flap base to blood flow cessation (Dist(with flow), in cm), percentage of viable skin (VA, in%), and qualitative analysis of blood flow by orthogonal polarization spectral imaging were performed at 1 and 24 hours and on the seventh post-operative day.

RESULT

Bands IV, V, and VI presented no flow independent of time. The functional capillary density group B was higher than that of groups C and P, primarily after 24 hours. All groups showed an increase in D with time but reached similar final distances (C = 2.73, B = 2.78 and P = 2.70 cm). Moreover, the percentage of viable areas remained at approximately 50%. The orthogonal polarization spectral imaging was useful to assess viability by counting fields with and without blood flow.

CONCLUSIONS

Functional capillary density values were higher in the buflomedil group compared to the control and pentoxifylline groups in this model. Functional capillary density did not influence D or the percentage of VA, and the technique showed favorable potential to assess/predict the viability of skin flaps within 1 h after surgery.

Protective effect of streptokinase on rat liver ischemia reperfusion injury

AIM: To study the protective effect of strep-tokinase on rat liver ischemia reperfusion injury.

METHODS: Thirty-six Wistar rats were divided randomly into control group and 2 experiment groups (12 in each group). Livers from the control group were perfused with 10 mL Ringer's solution through the portal vein and stored at 4 ℃ for 24 h. Livers from the experiment group were perfused with Ringer's solution containing 7500 IU streptokinase with or without hypothermal oxygen stored at 4 ℃ for 24 h. All cold storage livers were followed by in vitro perfusion at 37 ℃ for 45 min, and stored at 4 ℃. Changes in ALT, GLDH, and activity of PNP, 5'nucleotidase and bile secretion were detected.

RESULTS: The activity of ALT, GLDH and PNP was significantly lower in the experiment groups than in the control group(P < 0.05). Bile secretion(3.7 ± 0.7 µL/g at 45 min, 9.1 ± 0.7 µL/g at 45 min vs 1.1 ± 0.9 µL/g at 45 min, P < 0.05) and 5'nucleotidase activity were significantly increased in the experiment groups compared with the control group.

CONCLUSION: Streptokinase can improve rat liver microcirculation and ischemia reperfusion injury.

Ligustrazine alleviates acute renal injury in a rat model of acute necrotizing pancreatitis

AIM: To evaluate the effect of ligustrazine, a traditional Chinese medicine, on renal injury in a rat model of acute necrotizing pancreatitis (ANP).

METHODS: A total of 192 rats were randomly divided into three groups: control (C group), ANP without treatment (P group), and ANP treated with ligustrazine (T group). Each group was further divided into 0.5, 2, 6, 12 h subgroups. All rats were anesthetized with an intraperitoneal injection of sodium pentobarbital. Sodium taurocholate was infused through the pancreatic membrane to induce ANP. T group was infused sodium taurocholate as above, and 0.6% ligustrazine was then administered via the femoral vein. Serum urea nitrogen (BUN) and creatinine (Cr) concentrations were measured for the evaluation of renal function. The effects of ligustrazine on the severity of renal injury were assessed by renal function, TXA₂/PGI₂ and histopathological changes. Renal blood flow was determined by the radioactive microsphere technique (RMT).

RESULTS: Compared with control group, the renal blood flow in P group was decreased significantly. Serious renal and pancreatic damages were found in P group, the BUN and Cr levels were elevated significantly, and the ratio of TXA₂ to PGI₂ was increased at 2, 6 and 12 h. Compared with P group, the blood flow of kidney was elevated significantly at 6 and 12 h after induction of ANP, the renal and pancreatic damages were attenuated, and the BUN and Cr levels were decreased significantly, and the ratio of TXA₂ to PGI₂ was decreased at 6 and 12 h in T group.

CONCLUSION: Microcirculatory disorder (MCD) is an important factor for renal injury in ANP. Ligustrazine can ameliorate the condition of MCD and the damage of pancreas and kidney.

Preventive effect of tetramethylpyrazine on intestinal mucosal injury in rats with acute necrotizing pancreatitis

AIM: To evaluate the role of microcirculatory disorder (MCD) and the therapeutic effectiveness of tetramethylpyrazine (TMP) on intestinal mucosa injury in rats with acute necrotizing pancreatitis (ANP).

METHODS: A total of 192 Sprague-Dawley rats were randomly divided into three groups: normal control group (C group), ANP group not treated with TMP (P group), ANP group treated with TMP (T group). An ANP model was induced by injection of 50 g/L sodium taurocholate under the pancreatic membrane (4 mL/kg). C group received isovolumetric injection of 9 g/L physiological saline solution using the same method. T group received injection of TMP (10 mL/kg) via portal vein. Radioactive biomicrosphere technique was used to measure the blood flow at 0.5, 2, 6 and 12 h after the induction of ANP. Samples of pancreas, distal ileum were collected to observe pathological changes using a validated histology score. Intestinal tissues were also used for examination of myeloperoxidase (MPO) expressed intracellularly in azurophilic granules of neutrophils.

RESULTS: The blood flow was significantly lower in P group than in C group (P < 0.01). The pathological changes were aggravated significantly in P group. The longer the time, the severer the pathological changes. The intestinal MPO activities were significantly higher in P group than in C group (P < 0.01). The blood flow of intestine was significantly higher in T group than in P group after 2 h (P < 0.01). The pathological changes were alleviated significantly in T group. MPO activities were significantly lower in T group than in P group (P < 0.01 or P < 0.05). There was a negative correlation between intestinal blood flow and MPO activity (r = -0.981, P < 0.01) as well as between intestinal blood flow and pathologic scores (r = -0.922, P < 0.05).

CONCLUSION: MCD is an important factor for intestinal injury in ANP. TMP can ameliorate the condition of MCD and the damage to pancreas and intestine.

Epidural anaesthesia restores pancreatic microcirculation and decreases the severity of acute pancreatitis

AIM: To investigate the effect of epidural anaesthesia (EA) on pancreatic microcirculation during acute pancreatitis (AP).

METHODS: AP was induced by injection of sodium taurocholate into the pancreatic duct of Sprague-Dawley rats. To realize EA, a catheter was introduced into the epidural space between T7 and T9 and bupivacaine was injected. Microcirculatory flow was measured by laser Doppler flowmetry. Arterial blood gas analyses were performed. At the end of the experiment (≤ 5 h), pancreas was removed for histology. The animals were divided into three groups: Group 1 (n = 9), AP without EA; Group 2 (n = 4), EA without AP; and Group 3 (n = 6), AP treated by EA.

RESULTS: In Group 1, pancreatic microcirculatory flow prior to AP was 141 ± 39 perfusion units (PU). After AP, microcirculatory flow obviously decreased to 9 ± 6 PU (P < 0.05). Metabolic acidosis developed with base excess (BE) of - 14 ± 3 mmol/L. Histology revealed extensive edema and tissue necrosis. In Group 2, EA did not significantly modify microcirculatory flow. BE remained unchanged and histological analysis showed normal pancreatic tissue. In Group 3, AP initially caused a significant decrease in microcirculatory flow from 155 ± 25 to 11 ± 7 PU (P < 0.05). After initiation of EA, microcirculatory flow obviously increased again to 81 ± 31 PU (P < 0.05). BE was -6 ± 4 mmol/L, which was significantly different compared to Group 1 (P < 0.05). Furthermore, histology revealed less extensive edema and necrosis in pancreatic tissue in Group 3 than that in Group 1.

CONCLUSION: AP caused dramatic microcirculatory changes within the pancreas, with development of metabolic acidosis and tissue necrosis. EA allowed partial restoration of microcirculatory flow and prevented development of tissue necrosis and systemic complications. Therefore, EA should be considered as therapeutic option to prevent evolution from edematous to necrotic AP.

Macrophage inflammatory protein-2 contributes to liver resection-induced acceleration of hepatic metastatic tumor growth

AIM: To study the role of macrophage inflammatory protein (MIP)-2 in liver resection-induced acceleration of tumor growth in a mouse model of hepatic metastasis.

METHODS: After a 50% hepatectomy, 1×10⁵ CT26.WT cells were implanted into the left liver lobe of syngeneic balb/c mice (PHx). Additional animals were treated with a monoclonal antibody (MAB452) neutralizing MIP-2 (PHx+mAB). Non-resected and non-mAB-treated mice (Con) served as controls. After 7 d, tumor angiogenesis and microcirculation as well as cell proliferation, tumor growth, and CXCR-2 expression were analyzed using intravital fluorescence microscopy, histology, immunohistochemistry, and flow cytometry.

RESULTS: Partial hepatectomy increased (P < 0.05) the expression of the MIP-2 receptor CXCR-2 on tumor cells when compared with non-resected controls, and markedly accelerated (P < 0.05) angiogenesis and metastatic tumor growth. Neutralization of MIP-2 by MAB452 treatment significantly (P < 0.05) depressed CXCR-2 expression. Further, the blockade of MIP-2 reduced the angiogenic response (P < 0.05) and inhibited tumor growth (P < 0.05). Of interest, liver resection-induced hepatocyte proliferation was not effected by anti-MIP-2 treatment.

CONCLUSION: MIP-2 significantly contributes to liver resection-induced acceleration of colorectal CT26.WT hepatic metastasis growth.

Systemic phosphatidylcholine pretreatment protects canine esophageal mucosa during acute experimental biliary reflux

AIM: To characterize the consequences of short-term exposure to luminal bile on mucosal mast cell reactions in a canine model, and to determine the effects of systemic phosphatidylcholine pretreatment in this condition.

METHODS: Twenty mongrel dogs were used for experiments. Group 1 (n  = 5) served as a saline-treated control, while in group 2 (n = 5) the esophagus was exposed to bile for 3 h. In group 3 (n  = 5) the animals were pretreated with 7-nitroindazole to inhibit the neuronal isoform of nitric oxide synthase. In group 4 (n  = 5) phosphatidylcholine solution (50 mg/kg) was administered iv before the biliary challenge. Mucosal microcirculation was observed by intravital videomicroscopy. Myeloperoxidase and nitric oxide synthase activities, the degrees of mast cell degranulation and mucosal damage were evaluated via tissue biopsies.

RESULTS: Exposure to bile evoked significant mast cell degranulation and leukocyte accumulation. The red blood cell velocity and the diameter of the postcapillary venules increased significantly. The tissue ATP content and constitutive nitric oxide synthase activity decreased, while the inducible nitric oxide synthase activity increased significantly as compared to the control values. 7-nitroindazole treatment significantly exacerbated the mucosal mast cell degranulation and tissue damage. In contrast, phosphatidylcholine pretreatment prevented the bile-induced ATP depletion, the inducible nitric oxide synthase and myeloperoxidase activity and the mast cell degranulation increased.

CONCLUSION: The neuronal nitric oxide synthase - mast cell axis plays an important role in the esophageal mucosal defense system. Systemic phosphatidylcholine pretreatment affords effective protection through ameliorating the bile-induced ATP depletion and secondary inflammatory reaction.

Microcirculation disturbance affects rats with acute severe pancreatitis following lung injury

AIM: To study the effects of microcirculation disturbance (MD) on rats with acute severe pancreatitis (ASP).

METHODS: We developed ASP rat models, and anatomized separately after 1, 3, 5, 7, and 9 h. We took out blood and did hemorrheologic examination and erythrocyte osmotic fragility test, checked up the water content, capillary permeability, and genetic expression of intercellular adhesion molecule-1 (ICAM-1) in lung tissues, examined the apoptosis degree of blood vessel endothelium while we tested related gene expression of Bax and Bcl-2 in lung tissues. We did the same examination in control group.

RESULTS: The viscosity of total blood and plasma, the hematocrit, and the erythrocyte osmotic fragility were all increased. Fibrinogen was decreased. The water content in lung tissues and capillary permeability were increased. Apoptosis degree of blood vessel endothelium was increased too. ICAM-1 genetic expression moved up after 1 h and reached its peak value after 9 h.

CONCLUSION: MD plays an important role in ASP following acute lung injury (ALI). The functional damage of blood vessel endothelium, the apoptosis of capillary vessel endothelium, WBC edging-concentration and the increasing of erythrocyte fragility are the main reasons of ALI.

Impact of antithrombin III on hepatic and intestinal microcirculation in experimental liver cirrhosis and bowel inflammation: An in vivo analysis

AIM: To analyze the hepatic and intestinal microcirculation in an animal model of liver cirrhosis and inflammatory bowel disease (IBD) and to characterize the anti-inflammatory action of antithrombin III (ATIII) on leukocyte kinetics and liver damage.

METHODS: Hepatic and intestinal microcirculation was investigated by intravital videomicroscopy. Standardized models of experimental chronic liver cirrhosis and bowel inflammation were employed. Animals were divided into four groups (n = 6/group): controls, animals with cirrhosis, animals with cirrhosis and IBD, animals with cirrhosis and IBD treated with ATIII.

RESULTS: Cirrhosis facilitated leukocyte rolling and sticking in hepatic sinusoids (1.91±0.28 sticker/µm vs 0.5±0.5 sticker/µm in controls, P<0.05). The effect enhanced in animals with cirrhosis and IBD (5.4±1.65 sticker/µm), but reversed after ATIII application (3.97±1.04 sticker/µm, P<0.05). Mucosal blood flow showed no differences in cirrhotic animals and controls (5.3±0.31 nL/min vs 5.4±0.25 nL/min) and was attenuated in animals with cirrhosis and IBD significantly (3.49±0.6 nL/min). This effect was normalized in the treatment group (5.13±0.4 nL/min, P<0.05). Enzyme values rose during development of cirrhosis and bowel inflammation, and reduced after ATIII application (P<0.05).

CONCLUSION: Liver cirrhosis in the presence of IBD leads to a significant reduction in mucosal blood flow and an increase in hepatic leukocyte adherence with consecutive liver injury, which can be prevented by administration of ATIII.

Changes of gastric and intestinal blood flow, serum phospholipase A2 and interleukin-1β in rats with acute necrotizing pancreatitis

AIM: To explore the relationship between gastric and intestinal microcirculatory impairment and inflammatory mediators released in rats with acute necrotizing pancreatitis (ANP).

METHODS: A total of 64 rats were randomized into control group and ANP group. ANP model was induced by injection of 5% sodium taurocholate under the pancreatic membrane. Radioactive biomicrosphere technique was used to measure the gastric and intestinal tissue blood flow at 2 and 12 h after the induction of ANP, meanwhile serum phospholipase A₂ (PLA₂) activities and interleukin-1β levels were determined. Pathologic changes in pancreas, gastric and intestinal mucosae were studied.

RESULTS: The gastric blood flow in ANP group (0.62±0.06 and 0.35±0.05) mL/(min·g) was significantly lower than that in control group (0.86±0.11 and 0.85±0.06) mL/(min·g) (P<0.01) at 2 and 12 h after induction of ANP. The intestinal blood flow in ANP group (0.80±0.07 and 0.50±0.06) mL/(min·g) was significantly lower than that in control group (1.56±0.18 and 1.61±0.11) mL/(min·g) (P<0.01). Serum PLA₂ activities (94.29±9.96 and 103.71± 14.40) U/L and IL-1β levels (0.78±0.13 and 0.83±0.20) μg/L in ANP group were higher than those in control group (65.27±10.52 and 66.63±9.81) U/L, (0.32±0.06 and 0.33±0.07) μg/L (P<0.01). At 2 and 12 h after introduction of the model, typical pathologic changes were found in ANP. Compared with control group, the gastric and intestinal mucosal pathologic changes were aggravated significantly (P<0.01) at 12 h after induction of ANP. Gastric and intestinal mucosal necrosis, multiple ulcer and hemorrhage occurred.

CONCLUSION: Decrease of gastric and intestinal blood flow and increase of inflammatory mediators occur simultaneously early in ANP, both of them are important pathogenic factors for gastric and intestinal mucosal injury in ANP.

Protective effects of 5,4’-dihydroxy-3’,5’-dimethoxy-7-O-β-D-glucopyranosyloxy-flavone on experimental hepatic injury

AIM: To investigate the pharmacological effects of rice flavone (5,4’-dihydroxy-3’,5’-dimethoxy-7-O-β-D-glucopyranosyloxy-flavone, RF) separated from panicle-differentiating to flowing rice on rat experimental hepatic injury.

METHODS: Models of rat acute hepatic injury induced by carbon tetrachloride (CCl₄) administration, rat hepatic fibrosis induced by thioacetamide, injury of primary cultured rat hepatocytes induced by CCl₄, respectively, were established. After treated with RF, content of serum alanine transaminase (ALT), aspartate aminotransferase (AST) and albumin (Alb), hyaluronic acid (HA), the activity of glutathione peroxidase (GSH-Px), superoxide dismutase (SOD), and hydroxyproline (Hyp) were measured and liver tissue was observed pathologically by hematoxylin-eosin (HE) staining. Effects of RF on pathological changes, function index, enzyme of scavenging free radicals and blood rheology were evaluated.

RESULTS: In model of rat acute hepatic injury induced by CCl₄, RF can significantly decrease the contents of serum ALT, AST, increase the content of Alb, improve the dropsy and fat denaturalization of hepatocytes. In model of rat hepatic fibrosis induced by thioacetamide, RF can inhibit the increase of HA, Hyp and whole blood viscosity, and improve the activities of GSH-Px and SOD, and inauricular microcirculation.

CONCLUSION: RF has apparent protective effects on hepatic injury by increasing activity of GSH-Px and SOD, scavenging free radicals produced by CCl₄, reducing blood viscosity, and improving microcirculation and blood supply.

Disturbance of hepatic and intestinal microcirculation in experimental liver cirrhosis

AIM: To analyze hepatic, mesenteric and mucosal microcirculation and leukocyte-endothelium interaction (LEI) in a rat model with liver cirrhosis.

METHODS: Hepatic cirrhosis was induced in Wistar rats by gavage with carbon tetrachloride, and intravital videomicroscopy was performed in liver, mesentery and small intestine mucosa. Special emphasis is given on microcirculatory and morphometric changes during cirrhotic portal hypertension.

RESULTS: LEI was influenced significantly in the cirrhotic liver but not in the gut. Blood flow measurement showed significant differences among liver, main mesenteric vessels and the mucosa. The results of our study indicate that liver cirrhosis leads to alterations in hepatic and mesenteric blood flow but not in mucosal blood flow.

CONCLUSION: The enhanced inflammatory response in hepatic microvessels may be caused by a decrease of antithrombin III levels and could be responsible for disturbances of organ pathology.

Differences in platelet endothelial cell adhesion molecule-1 expression between peripheral circulation and pancreatic microcirculation in cerulein-induced acute edematous pancreatitis

AIM: To investigate the changes of platelet endothelial cell adhesion molecule-1 (PECAM-1) expression on polymorphonuclear leukocytes (PMNs) in peripheral circulation and pancreatic microcirculation in cerulein-induced acute edematous pancreatitis (AEP).

METHODS: Fifty Wistar rats were randomly divided into control group (n = 10) and AEP group (n = 40). A model of AEP was established by subcutaneous injection of cerulein 5.5 and 7.5 μg/kg at 0 and 1 h after the beginning of experiment respectively. PECAM-1 expression on PMNs from splenic vein and inferior vena cava was determined by RT-PCR at mRNA level and determined by flow cytometry at protein level.

RESULTS: In experimental rats, an increased PECAM-1 mRNA expression was seen from 4 to 8 h of AEP in peripheral circulation (0.77±0.25%, 0.76±0.28%, 0.89±0.30%, 1.00±0.21%), while in pancreatic microcirculation, expression decreased from 2 h and reached the lowest level at 6 h of AEP (0.78±0.29%, 0.75±0.26%, 0.62±0.28%, 0.66±0.20%). There were significant differences at 8-h time point of AEP between peripheral circulation and pancreatic microcirculation (1.00±0.21% vs 0.66±0.20%, P<0.05). Meanwhile, the difference at protein level was also found.

CONCLUSION: A reverse expression of PECAM-1 on PMNs was found between peripheral circulation and pancreatic microcirculation, suggesting that inhibition of PECAM-1 expression may improve the pathological change of AEP.