Intravenous contrast medium aggravates the impairment of pancreatic microcirculation in necrotizing pancreatitis in the rat.

BACKGROUND: Previous reports demonstrated that radiographic contrast medium, as used in contrast-enhanced computed tomography, increases acinar necrosis and mortality in experimental pancreatitis. The authors studied the possibility that these changes may be related to an additional impairment of pancreatic microcirculation. METHODS: Fifty Wistar rats had acute pancreatitis induced by intraductal glycodeoxycholic acid (10 mmol/L for 10 min) and intravenous cerulein (5 micrograms/kg/hr for 6 hrs). After rehydration (16 mL/kg), pancreatic capillary perfusion was quantified by means of intravital microscopy at baseline before intravenous infusion of contrast medium (n = 25) or saline (n = 25), and 30 and 60 minutes thereafter. In addition to total capillary flow, capillaries were categorized as high- or low-flow (> or < 1.6 nL/min). RESULTS: Pancreatic capillary flow did not change in either high- or low-flow capillaries after saline infusion. However, contrast medium infusion induced a significant decrease of total capillary flow (p < 0.001). Analysis according to the relative flow rate revealed that this was primarily because of a significant additional reduction of perfusion in low-flow capillaries (p < 0.0001). Furthermore, complete capillary stasis was observed in 15.9 +/- 3.4% after contrast medium as compared with 3.2 +/- 1.2% after saline infusion (p < 0.006). CONCLUSION: Radiographic contrast medium aggravates the impairment of pancreatic microcirculation in experimental necrotizing pancreatitis.     

Pancreatic capillary blood flow in an improved model of necrotizing pancreatitis in the rat

INTRODUCTION: The development of acute pancreatitis is characterized by profound changes in pancreatic microcirculation. Using in vivo microscopy with fluorescent-labeled erythrocytes as tracers we studied changes in pancreatic microcirculation in an improved rat model of necrotizing pancreatitis (NP) in comparison to edematous pancreatitis (EP) and healthy controls. METHODS: Twenty-one male Wistar rats had their pancreatae exteriorized in a temperature-controlled immersion chamber followed by intravenous administration of fluorescent-labeled autologous erythrocytes. EP was induced by intraductal saline and intravenous caerulein (5 microg/kg/h) for 6 h (n = 7) and NP by controlled intraductal infusion of glycodeoxycholic acid (10 mmol/L) followed by intravenous caerulein (n = 7). Control animals received intraductal and intravenous saline (n = 7). The determination of pancreatic microcirculation was performed before as well as 1, 3, and 6 h after intraductal infusion by correlating the number of passing labeled erythrocytes/capillary/min with their concentration per microliter of arterial blood. RESULTS: Pancreatic capillary flow in control animals remained constant over the 6-h observation period. Pancreatic capillary flow in the EP group rapidly increased to 188% of baseline after 3 h and remained significantly elevated throughout the experiments (P = 0.0001). In contrast, pancreatic capillary flow decreased significantly in the group suffering NP with values 46.7% of baseline after 6 h (P = 0.0001). Complete capillary stasis developed in 38% of investigated capillaries in the NP group compared to 0-1% in both other groups (P = 0.0001). CONCLUSION: Pancreatic microcirculation in mild edematous pancreatitis is significantly increased while the evolution of necrotizing pancreatitis in the model studied herein is characterized by a dramatic reduction in pancreatic capillary flow in conjunction with areas of capillary stasis. These results underline the pathophysiologic relevance of the model and of therapeutic measures aimed at an improvement of pancreatic microcirculation in clinical necrotizing pancreatitis.     

Pulmonary microcirculation in mild and severe experimental pancreatitis

BACKGROUND: Research aimed at elucidating the pathogenesis of pancreatitis-associated lung injury and evaluating novel strategies for preventing respiratory complications in acute pancreatitis (AP) has not yet involved intravital microscopic (IVM) studies of pulmonary microcirculation in animals with severe disease. OBJECTIVE: To characterize and compare pulmonary microcirculation in severe/necrotizing (NP) and mild/edematous pancreatitis (EP) in the rat. METHODS: EP was induced by intravenous cerulein infusion (n = 10) and NP by a standardized intraductal infusion of glycodeoxycholic acid followed by intravenous cerulein (n = 10). After 24 h a left-sided thoracotomy was performed for IVM examination of pulmonary capillary blood flow, permeability, leukocyte sticking and the thickness of alveolar septi. Further measurements included monitoring of arterial blood gases and histological evaluation of lung injury. RESULTS: In animals with NP, histology revealed severe pulmonary edema together with clustering of polymorphonuclear leukocytes in pulmonary microvessels and alveoli. IVM showed a greater number (n) of leukocytes sticking on the endothelium of pulmonary capillaries (9.4 +/- 0.7 vs. 1.8 +/- 0.2 in healthy control animals) and increased capillary permeability (260 +/- 14 vs. 136 +/- 6% relative fluorescein intensity) while capillary blood flow was decreased (0.41 +/- 0.05 vs. 0.57 +/- 0.03 mm/s). In comparison, changes in EP were significantly less pronounced (flow 0.5 +/- 0.04 mm/s, permeability 156 +/- 4%, leukocyte sticking n = 4.6 +/- 0.7). CONCLUSIONS: These findings suggest that deterioration of pulmonary microcirculation in AP correlates with disease severity and that a model featuring NP may therefore be more suitable to further study pancreatitis-associated pulmonary injury.     

Effects of dopexamine on acute necrotising pancreatitis in rats.

OBJECTIVE: To examine the effects of dopexamine on pancreatic tissue oxygen tension (PtO2) and the extent of acinar injury in rats with acute necrotising pancreatitis DESIGN: Laboratory study. SETTING: Medical school, Turkey. ANIMALS: 68 Sprague Dawley rats. MAIN OUTCOME MEASURES: Cardiorespiratory measurements, pancreatic PtO2, effects on activity of serum amylase and concentration trypsinogen activation peptide (TAP). and histological picture. RESULTS: The four study groups (sham + saline, sham + dopexamine, acute pancreatitis and acute pancreatitis + dopexamine) were each divided into two; in 9 rats in each, pancreatic biochemistry was studied, and in the remaining 8 in each group serum biochemistry and histology were studied. The groups were comparable with regard to mean arterial pressure, heart rate, arterial blood gases, packed cell volume, and serum amylase activity. The use of dopexamine increased pancreatic PtO2 in the sham + dopexamine group without the important blood pressure changes. The induction of pancreatitis resulted in a significant reduction in pancreatic PtO2 in the pancreatitis groups. The use of dopexamine did not increase pancreatic PtO2. There were no significant differences in plasma TAP concentration and the extent of acinar cell injury in the animals in the pancreatitis groups. CONCLUSION: Treatment with dopexamine does not improve the pancreatic microcirculation or reduce the extent of acinar cell injury in acute necrotising pancreatitis and is therefore unlikely to be of benefit in patients with pancreatitis.     

前列腺素E_1防治大鼠急性坏死性胰腺炎的作用及机理

研究前列腺素E_1防治大鼠急性坏死性胰腺炎的作用及其机理。方法:向大鼠胰管内注射5％牛磺胆酸钠溶液制成急性坏死性胰腺炎(ANP)模型。结果:ANP时,胰腺毛细血管通透性(PCP)明显增高,胰腺组织中性粒细胞过氧化酶(MPO)活性及脂质过氧化物(LPO)水平明显增高。病理示组织内大量PMN浸润、片状出血、坏死。PGE_1使PCP明显下降,MPO、LPO显著降低,动物存活明显改善结论:PGE_1通过抑制中性粒细胞(PMN)活化减少氧自由基(OFR)释放,减轻血管内皮细胞及胰腺组织损伤。     

一种研究急性胰腺炎加重病理机理的动物模型

介绍一种急性水肿性胰腺炎（ＡＥＰ）向坏死性胰腺炎（ＡＮＰ）转变的大鼠模型。１０７只ＳＤ大鼠随机分为假手术组、ＡＥＰ组和ＡＮＰ组。ＡＥＰ通过胰管结扎、外分泌刺激诱发。在ＡＥＰ模型基础上静注大剂量Ｄｅｘｔｒａｎ１１０诱发ＡＮＰ。结果显示：血清淀粉酶水平在ＡＥＰ、ＡＮＰ组明显增高，胰腺泡细胞胞浆游离钙离子浓度在ＡＮＰ诱发后持续增高；胰腺出血、实质坏死、钙沉积在ＡＮＰ组常见。超微结构显示ＡＮＰ组胰毛细血管内皮剥脱、坏死。由此表明，胰腺缺血可能通过腺泡细胞钙超负荷的作用促发ＡＥＰ向ＡＮＰ转变。该大鼠模型因临床联系较好、病变渐进，不失为一种从细胞和分子水平研究急性胰腺炎加重病理机理的动物模型     

急性胰腺炎大鼠TNF-α mRNA、IL-10 mRNA表达和胰腺细胞凋亡的研究

目的 探讨大鼠急性胰腺炎早期胰腺组织中TNF－αmRNA、IL－10mRNA的表达和细胞凋亡的变化规律。方法 以牛磺胆酸钠诱导20只大鼠急性水肿性胰腺炎（AEP）模型,20只急性坏死性胰腺炎（ANP）模型,另取10只正常大鼠作为对照。术后12h各处死10只大鼠,检测血清和胰腺组织中的TNF－α和IL－10水平,分析两者在胰腺组织中的mRNA较录水平,检测胰腺细胞的凋亡率。结果 正常、AEP和ANP组的细胞凋亡率分别为2．98％、17．29％和8．39％。制模后TNF－αm和IL－10增强ANP大鼠TNF－α表达增强。结论 急性胰腺炎大鼠胰腺组织中的TNF－α和IL－10的表达与其在血清和胰腺中的浓度成正比,胰腺本身可能就是产生细胞因子的主要器官。胰腺细胞凋亡率与疾病的严重程度呈负相关,凋亡是对胰腺损伤的良好反应。     

Electron microscopy of the exocrine pancreas in experimental acute hypercalcemia

Hypercalcemia has been associated with acute pancreatitis clinically and in the experimental animal. We studied the pancreatic ultrastructure in acute experimental hypercalcemia. Anesthetized cats (Pentobarbital, 0.55 mg/kg) received Ca++ (Calcium-Gluconate: 0.6 mmol/kgh; n = 4), K+ (KCl: 1.1 mmol/kgh; n = 4) or NaCl (0.9%; n = 4) locally through retrograde infusion into the splenic artery. Biopsies for electron microscopy (EM) were taken at three hours. Eight cats received intravenous Ca++ (0.6 mmol/kgh, 0.3 mmol/kgh after three hours) or NaCl (0.9%) for 12 hours. Biopsies were collected in two animals in three-hour intervals, and in all animals at twelve hours. After local calcium infusion necrotizing pancreatitis was seen macroscopically in the body of the pancreas. Biopsies for EM showed acinar cell necrosis, hydrops of nuclei and mitochondria and needle-like precipitates in the cytoplasma in the center of calcium perfusion. Biopsies taken from the peripheral region of the macroscopically altered tissue revealed desorganisation of the acinar polarisation and the endoplasmic reticulum, with zymogen granules appearing in the basolateral cell-portion. After intravenous calcium administration no macroscopical changes were seen. In EM acinar cells showed dilatation and proliferation of the golgi apparatus and increased number of condensing vacuoles indicating stimulation. Again, disorganisation of acinar cell polarisation was present. Control animals treated with K+ or NaCl showed normal pancreatic ultrastructure. The morphological changes after calcium infusion indicate direct damage to the acinar cell. Our results suggest that hypercalcemia induced pancreatitis could originate in the acinar cell.     

Endothelin receptor blockade improves fluid sequestration, pancreatic capillary blood flow, and survival in severe experimental pancreatitis.

OBJECTIVE: To evaluate the effect of a new endothelin receptor antagonist (ET-RA) on the course of severe experimental pancreatitis. BACKGROUND: Endothelin-1 has been shown to reduce regional blood flow in various organs, including the pancreas, and to aggravate cerulein-induced mild pancreatitis. METHODS: Acute necrotizing pancreatitis (ANP) was induced in rats by standardized intraductal bile acid infusion and cerulein hyperstimulation. Serum trypsinogen activation peptides (TAP) were measured to verify comparable disease severity. Starting 6 hours after the onset of ANP, animals randomly received either saline or the new ET-RA LU-135252. Monitoring included cardiorespiratory parameters, urine output, hematocrit, and TAP levels. After 24 hours, animals were relaparotomized to determine pancreatic capillary blood flow and to assess the amount of free intraabdominal fluid and acinar cell necrosis. Survival was determined in a second set of experiments on 24 animals observed for 48 hours after pancreatitis induction and treatment with either normal saline or ET-RA. RESULTS: Comparable TAP increases confirmed equally severe ANP in both groups before treatment. Treatment with ET-RA significantly reduced the mortality rate, from 50% in untreated animals to 8%. Improved survival was associated with significantly decreased hematocrit, improved urinary output, decreased ascites, and increased pancreatic capillary blood flow. There were no significant differences in plasma TAP and acinar cell injury in the surviving animals of the two treatment groups. CONCLUSION: Therapy with the new ET-RA reduces the early mortality rate in experimental ANP, probably by reducing fluid sequestration and improving microcirculation.     

Phospholipase A2 isoforms in acute pancreatitis

OBJECTIVE: To assess phospholipase A2 isoforms during human and experimental acute necrotizing pancreatitis. Phospholipase A2 isoforms (group I, II, and IV) were examined in acute pancreatitis tissues in humans and rats to determine whether the exocrine pancreas itself is a source of these mediators. SUMMARY BACKGROUND DATA: Phospholipase A2 has important regulatory functions, especially in inflammation. METHODS: Using Northern blot analysis and immunohistochemistry, the expression and localization of phospholipase A2 isoforms were analyzed in pancreatic tissue obtained from 21 patients with acute necrotizing pancreatitis and in pancreatic tissues of rats with acute edematous and necrotizing pancreatitis. Rat samples were examined daily for 1 week. RESULTS: In human acute pancreatitis, phospholipase A2-I mRNA expression was 8.9-fold decreased. By contrast, phospholipase A2-II (7.8-fold) and phospholipase A2-IV (8.1-fold) mRNA levels were increased. By in situ hybridization, phospholipase A2-IV was found to be expressed in remaining acinar and ductal cells adjacent to the necrotic areas. Immunostaining revealed moderate to intense phospholipase A2-II immunoreactivity in remaining acinar and ductal cells next to the necrosis. In rat pancreatitis, phospholipase A2-II mRNA levels in the pancreas were unchanged in the early phase (8 hours) but markedly increased after 24 hours, with a fluctuating pattern until day 7. CONCLUSIONS: Enhanced expression of phospholipase A2-II and A2-IV isoenzymes in human and experimental acute pancreatitis suggests that these enzymes play a role in modulating the inflammatory reaction in the pancreas. Because phospholipase A2-II and A2-IV mRNA was strongly present in remaining viable pancreatic acinar and ductal cells, the pancreas itself seems to be at least partly a source and a regulator of phospholipase A2-II- and A2-IV-dependent inflammatory reactions in acute pancreatitis.     

Effect of ethanol on pancreatic interstitial pH and blood flow in cats with chronic pancreatitis.

OBJECTIVE: The objective of this study was to investigate the effects of ethanol on pancreatic blood flow and interstitial pH in chronic pancreatitis. BACKGROUND: Ethanol is known to contribute to the development of both acute and chronic pancreatitis. However, it is unclear how ethanol precipitates episodes of acute pancreatic inflammation in the setting of chronic pancreatitis. In a model of chronic pancreatitis in cats, it is known that pancreatic blood flow is abnormally low and decreases further after ethanol ingestion. Because it is possible that this reduction in blood flow might be damaging to the pancreas, we investigated the effects of ethanol on pancreatic interstitial pH, an index of pancreatic ischemia. METHODS: In normal cats and cats with obstructive chronic pancreatitis, pancreatic blood flow and interstitial pH were measured using the hydrogen gas clearance technique and pH microelectrode, respectively. RESULTS: In normal cats, intragastric, but not intravenous, ethanol reduced both pancreatic blood flow by 62% (p < 0.05) and interstitial pH (7.38 +/- 0.03 to 7.20 +/- 0.03, p < 0.05). In cats with chronic pancreatitis in which basal pancreatic blood flow was already only 60% of normal flow, both intragastric and intravenous ethanol decreased both pancreatic blood flow (intragastric, 40% decrease, p < 0.05; intravenous, 34% decrease, p < 0.05) and interstitial pH (intragastric, 7.24 +/- 0.04 to 7.08 +/- 0.04, p < 0.05; intravenous 7.20 +/- 0.08 to 7.07 +/- 0.07, p < 0.05). CONCLUSIONS: This profound decrease in pH, lasting up to 2 hours after ethanol exposure in the chronic pancreatitis animals, suggests the possibility of ischemic cellular damage to the pancreas. These findings may explain the pathogenesis of bouts of acute pancreatic inflammation after ethanol ingestion in the setting of chronic disease.     

缺血-再灌注损伤对大鼠急性胰腺炎胰腺细胞凋亡的影响

目的探讨缺血一再灌注(I／R)损伤对大鼠急性胰腺炎(AP)胰腺细胞凋亡的影响。方法将SD大鼠54只按编号法随机分为对照组(n=6)、胰腺炎组(n=24)和I／R损伤组(n=24)。经胆胰管逆行加压注入3％牛磺胆酸钠建立大鼠AP模型，在此基础上，I／R损伤组通过暂时阻断脾下动脉造成局部胰腺I／R模型，对照组于术后lh，其余两组于术后1h、3h、6h和12h采取断颈方法分批处死动物，应用末端脱氧核苷酸转换酶(TdT)介导的原位末端标记(TUNEL)法检测缺血一再灌注区胰腺细胞凋亡。并观察其病理改变。结果胰腺炎组大鼠术后1h、3h胰腺组织仅为充血、水肿性改变，6h出现出血、坏死性改变；而1／R损伤组大鼠术后1h缺血一再灌注区胰腺呈现出血、坏死性改变，病变持续加重；AP后胰腺凋亡细胞明显增多，I／R损伤组和胰腺炎组的凋亡细胞高峰值分别在术后3h和6h；I／R损伤组术后1h、3h缺血一再灌注区胰腺凋亡细胞显著高于相应时相的胰腺炎组(P＜0．01，P＜0．05)．而6h、12h明显低于胰腺炎组(P＜O．05，P＜O．01)。结论I／R损伤在促发胰腺炎从水肿型向出血坏死型转化过程中，同时诱导胰腺细胞凋亡，细胞凋亡可能是阻止AP病变加重的一个有利反应。     

Contrast-enhanced computed tomography in acute pancreatitis: does contrast medium worsen its course due to impaired microcirculation?

Background An early and accurate diagnosis of severe acute (necrotizing) pancreatitis is important to allow timely institution of therapy to limit the extra-pancreatic sequelae of this necrotizing process and to minimize the incidence of super-infection of the necrosis (i.e., progression to infected necrosis). Contrast-enhanced computed tomography (CECT) has become the cornerstone of diagnosis by confirming the clinical diagnosis of severe acute pancreatitis based on the various clinical scoring criteria. Moreover, CECT serves as an anatomic roadmap for guiding radiological and surgical interventions. However, still-controversial experimental studies in animals in the mid-1990s suggested that the use of intravenous radiographic contrast media early in the course of the disease might exacerbate the necrotizing process by further impairing the already compromised pancreatic microcirculation. A series of experimental and clinical studies followed that have both refuted and supported this claim; unfortunately, none is conclusive, and the topic remains, as yet, unresolved.Aims Our objective was to review objectively the available literature found by a Medline search on this subject.Methods Meta-analysis and review.Results and conclusion Our conclusion, after analysis of these studies, is that there are no well-substantiated data that could resolve the controversy. However, several caveats will be offered.     

Extrapancreatic multiorgan injury in a severe sublethal acute pancreatitis model

In order to develop a new severe but sublethal acute pancreatitis model for the study of clinically relevant extrapancreatic multiorgan injury, we have induced acute pancreatitis in a rat model by intraductal injection with low dose and moderate concentration of bile acid under low pressure. We examined the structural and functional features in the pancreas, lung, liver and kidney. The animals were divided into two groups: the bile acid injection group and the control group. In the bile acid injection group, acute necrotizing pancreatitis was induced by intraductal administration of 0.2 ml of 2.0% bile acid under 30 cm H2O pressure, while the controls underwent the sham operation. The two groups were divided into six subgroups (8 rats for each) and sacrificed at 12, 24, 36, 48, 72 and 144 h, respectively. The pancreatitis induced hyperamylasemia, ascites, pancreatic oedema, haemorrhage, acinar cell necrosis and extensive fat necrosis without early mortality. Accompanied with the pancreatic injury, the function and histologic changes have developed continuously in the kidney and liver for 72 and 144 h in the bile acid injection animals respectively. No pancreatitis associated pulmonary changes were found. Taking into account the results with the two previously developed models of pancreatitis, we conclude that the extrapancreatic injury in acute pancreatitis is found in the liver, kidney and lung, in that order, depending on the severity of pancreatitis. The present sublethal pancreatitis model, in comparison with the two previously studied acute pancreatitis models, is perfect for pathogenetic and therapeutic study of liver and renal changes in acute necrotizing pancreatitis.     

Pancreatic structure and glucose tolerance in a longitudinal study of experimental pancreatitis-induced diabetes.

Chronic pancreatitis is associated with glucose intolerance and resultant pancreatogenic diabetes. Using the canine pancreatic duct-ligated model of pancreatitis, we serially evaluated pancreatic histology and electron microscopy, tolerance to intravenous and oral glucose, and insulin response to glucose loading. Pancreatic duct ligation caused microscopic evidence of acute pancreatitis at 1 week, progressing to acinar loss and fibrosis consistent with chronic pancreatitis at time periods up to 6 months. The islets of Langerhans showed degranulation early and appeared to be structurally preserved late. Calculated K values indicated a progressive significant deterioration in intravenous glucose tolerance, falling significantly from 3.46 +/- 0.23 basally to 1.51 +/- 0.17 at 6 months after duct ligation (p less than 0.0001). Oral glucose tolerance deteriorated significantly, with the integrated glucose response rising from 23.7 +/- 1.2 g/dl.minute basally to 32.3 +/- 2.8 g/dl.minute at 6 months after duct ligation (p less than 0.05). Integrated insulin response to both intravenous and oral glucose deteriorated with pancreatitis. Pancreatitis-induced glucose intolerance is a consistent feature of this duct-ligated model. Glucose intolerance stabilizes between 4 and 6 months after duct ligation and is associated with pancreatic acinar fibrosis and pancreatic endocrine structural preservation. While the mechanism of altered glucose tolerance may involve mechanical, neural, humoral, or vascular events, our data clearly support the conclusion that pancreatic ductal stenosis with resultant pancreatic fibrosis and chronic pancreatitis is associated with abnormal islet responsiveness leading to circulating insulin deficiency and glucose intolerance, despite histologic and ultrastructural evidence of intact islets of Langerhans.     

Intestinal microcirculation and gut permeability in acute pancreatitis: Early changes and therapeutic implications

Translocation of bacteria from the intestine causes local and systemic infection in severe acute pancreatitis. Increased intestinal permeability is considered a promoter of bacterial translocation. The mechanism leading to increased gut permeability may involve impaired intestinal capillary blood flow. The aim of this study was to evaluate and correlate early changes in capillary blood flow and permeability of the colon in acute rodent pancreatitis of graded severity. Edematous pancreatitis was induced by intravenous cerulein; necrotizing pancreatitis by intravenous cerulein and intraductal glycodeoxycholic acid. Six hours after induction of pancreatitis, the permeability of the ascending colon was assessed by the Ussing chamber technique; capillary perfusion of the pancreas and colon (mucosal and subserosal) was determined by intravital microscopy. In mild pancreatitis, pancreatic capillary perfusion remained unchanged (2.13 ± 0.06 vs. 1.98 ± 0.04 nl-min^−l.cap ⁻¹ [control]; P = NS), whereas mucosal (1.59 _± 0.03 vs. 2.28 ± 0.03 nl.min^−l.cap ⁻¹ [control]; P <0.01) and subserosal (2.47 ± 0.04 vs. 3.74 ± 0.05 nl-min^−l.cap ^-1 [control]; P <0.01) colonic capillary blood flow was significantly reduced. Severe pancreatitis was associated with a marked reduction in both pancreatic (1.06 = 0.03 vs. 1.98 ± 0.04 nl’min^-1.cap ^-1 [control]; P <0.01) and colonic (mucosal: 0.59 = 0.01 vs. 2.28 ± 0.03 nl.min^−l.cap ^-1 [control], P < 0.01; subserosal: 1.96 ± 0.05 vs. 3.74 ± 0.05 nl.min^−l.cap ^-1 [control], P <0.01) capillary perfusion. Colon permeability tended to increase with the severity of the disease (control: 147 ±19 nmol.hr^−l.cm {−2}2; mild pancreatitis: 158±23 nmol-hr^−l.cm^-2; severe pancreatitis: 181 ±33 nmol.hr^−l.cm^-2; P = NS). Impairment of colonic capillary perfusion correlates with the severity of pancreatitis. A decrease in capillary blood flow in the colon, even in mild pancreatitis not associated with significant protease activation and acinar cell necrosis or impairment of pancreatic capillary perfusion, suggests that colonic microcirculation is especially susceptible to inflammatory injury. There was no significant change in intestinal permeability in the early stage of pancreatitis, suggesting a window of opportunity for therapeutic interventions to prevent the later-observed increase in gut permeability, which could result in improved intestinal microcirculation. Presented at the Thirty-Seventh Annual Meeting of The Society for Surgery of the Alimentary Tract, San Diego, Calif., May 19–22, 1996. Supported in part by Deutsche Forschungsgemeinschaft (DFG Fo 197/3).     

Inosine reduces microcirculatory disturbance and inflammatory organ damage in experimental acute pancreatitis in rats

BACKGROUND: Despite improvement in the management of severe necrotizing pancreatitis, mortality remains high. Today, no specific treatment exists. Inflammatory cascades and microcirculatory disturbances play a key role in the pathogenesis of acute pancreatitis. The aim of the present study was to evaluate the effects of inosine, an immunomodulatory substance, on the severity of experimental necrotizing pancreatitis. METHODS: Severe necrotizing pancreatitis was induced in rats. Treatment groups received inosine either prophylactically or therapeutically. Pancreatic injury was evaluated by microcirculatory assessment and histology. RESULTS: Prophylactic inosine significantly attenuated pancreatic microcirculatory disturbances and morphologic injury in necrotizing pancreatitis. However, inosine treatment did not have any beneficial effects when applied therapeutically several hours after onset of the disease. CONCLUSIONS: Prophylactic inosine reduces microcirculatory and pancreatic injury in acute necrotizing pancreatitis. These effects should be assessed in the clinical setting of ERCP and pancreas transplantation.     

ET-1 induces pancreatitis-like microvascular deterioration and acinar cell injury.

Using in vivo microscopy red blood cell (RBC) velocities, functional capillary density (FCD) and capillary diameters were estimated after inducing acute pancreatitis by intraductal infusion of sodium taurocholate (0.8 ml; 4%) or after topical superfusion of the pancreas with ET-1 (100 pmol). Sodium taurocholate mediated a significant decrease in RBC velocities between 50 and 70%, transient decrease in capillary diameters by 10%, and a sustained decrease in FCD between 60 and 70% paralleled by a dramatic heterogeneity in blood flow. Topical superfusion of the exteriorized pancreas with ET-1 caused a significant decrease in RBC velocities between 65 and 75%, a sustained decrease in capillary diameters by 10%, and a decrease in FCD by 45% accompanied by an increase in flow heterogeneity. Following sodium taurocholate infusion pancreas histology revealed a severe edema and sublobular acinar cell necrosis, while topical ET-1 application displayed a severe edema of the pancreas with focal acinar cell necrosis. Thus, ET-1 mediated a deterioration of the pancreatic microcirculation, which is similar to the microcirculatory failure found in sodium taurocholate-induced experimental pancreatitis and was associated with focal acinar cell necrosis. We are thus inclined to hypothesize that endothelin released by injured endothelial cells during acute biliary pancreatitis promotes microcirculatory failure and ischemia in acute pancreatitis, eventually leading to acinar cell necrosis.     

Enterokinase induces severe necrosis and rapid mortality in cerulein pancreatitis: characterization of a novel noninvasive rat model of necro-hemorrhagic pancreatitis

BACKGROUND: Unlike edematous pancreatitis, induction of severe necrotizing pancreatitis in rats generally requires an invasive laparotomy with infusion and/or ligation of the pancreatic duct or duodenal or arterial occlusion. The aim of this study was to establish and characterize a noninvasive model of severe acute pancreatitis in rats. METHODS: Wistar rats were infused intravenously with cerulein or a combination of cerulein and enterokinase. Saline (154-mmol/L NaCl) or enterokinase only was infused in controls. In a first set of experiments, intrapancreatic protease activation and the release of cytokines were correlated with the severity of organ injury. Pancreatic and pulmonary injuries were determined at 6 h. In a second set of experiments, we assessed 24-h survival, serum parameters possibly reflecting the course of the disease, and morphologic changes later in the course of the disease. RESULTS: The severity of pancreatic injury and survival were correlated strongly with the amount of enterokinase infused simultaneously with cerulein. Trypsin as well as elastase and cathepsin B activity in pancreatic tissue samples were increased markedly in these animals. Marked pancreatic hemorrhage, necrosis, and leukocyte infiltration were present in animals with the greatest amounts of enterokinase infused. IL-6 and LDH, but not IL-1beta, CRP, and amylase, in serum correlated with the severity of pancreatitis. CONCLUSIONS: This noninvasive rat model of acute pancreatitis is characterized by major pancreatic necrosis, hemorrhage, and fatality. The simple and noninvasive induction technique may have advantages for future studies on inflammatory changes and sepsis in necrotizing pancreatitis compared with other currently available invasive models.     

Pathogenesis and prevention of early pancreatic infection in experimental acute necrotizing pancreatitis.

OBJECTIVE: The authors test antibiotic strategies aimed at either mitigating bacterial translocation from the gut or delivering antibiotics specifically concentrated by the pancreas for prevention of early secondary infection after acute necrotizing pancreatitis. BACKGROUND: Infection currently is the principal cause of death after severe pancreatitis. The authors have shown that the risk of bacterial infection correlates directly with the degree of tissue injury in a rodent model of pancreatitis. Bacteria most likely arrive by translocation from the colon. METHODS: Severe acute necrotizing pancreatitis was induced in rats by a combination of low-dose controlled intraductal infusion of glycodeoxycholic acid superimposed on intravenous cerulein hyperstimulation. At 6 hours, animals were randomly allocated to five treatment groups: controls, selective gut decontamination (oral antibiotics and cefotaxime), oral antibiotics alone, cefotaxime alone, or imipenem. At 96 hours, surviving animals were killed for quantitative bacterial study of the cecum, pancreas, and kidney. RESULTS: The 96-hour mortality (35%) was unaffected by any treatment regimen. Cecal gram-negative bacteria were significantly reduced only by the oral antibiotics. Pancreatic infection was significantly reduced by full-gut decontamination and by imipenem, but not by oral antibiotics or by cefotaxime alone. Renal infection was reduced by both intravenous antibiotics. CONCLUSIONS: Early pancreatic infection after acute necrotizing pancreatitis can be reduced with a full-gut decontamination regimen or with an antibiotic concentrated by the pancreas (imipenem) but not by unconcentrated antibiotics of similar spectrum (cefotaxime) or by oral antibiotics alone. These findings suggest that 1) both direct bacterial translocation from the gut and hematogenous seeding interplay in pancreatic infection while hematogenous seeding is dominant at extrapancreatic sites and 2) imipenem may be useful in clinical pancreatitis.