Trypsinogen Activation Peptide Levels Research Articles

Establishment and evaluation of a Beagle model of grade III pancreatic trauma.

Pancreatic trauma (PT) is a severe abdominal injury that is often combined with multiple organ injury. It is a severe disease that is difficult to diagnose and has a high mortality rate, particularly for grade III PT. The pathogenesis, disease progress and complications have not been fully investigated due to the lack of a reliable animal model. To address this, a Beagle model of grade III PT was established in the present study using a procedure involving rupture of the main pancreatic duct. Peripancreatic effusions and the degree of pancreatic damage were examined by routine ultrasound and contrast-enhanced ultrasound (CEUS). Also, ascites were collected for the examination of amylase and lipase levels, and whole blood samples were collected for the analysis of amylase, lipase, C-reactive protein (CRP), interleukin (IL)-6 and tumor necrosis factor (TNF)-α levels in the serum. Urine samples were also collected for the examination of trypsinogen activation peptide (TAP). In addition, the pancreas was sectioned and stained with hematoxylin and eosin. In comparison with routine ultrasound, CEUS showed a large area of focal trauma, with a depth greater than half of the anteroposterior diameter of the pancreas, with a clear boundary, clear capsular rupture and trauma induced by active bleeding. The volume of ascites peaked at 48 h post-trauma and decreased thereafter. Amylase and lipase levels in the ascites were elevated at 24 h post-trauma and significantly decreased at 48 and 72 h post-trauma (P<0.01). In addition, serum amylase and lipase levels increased to peak levels at 48 h post-trauma and then decreased (P<0.05), while serum CRP, IL-6 and TNF-α levels peaked at 24 h post-trauma and then decreased (P<0.05). Urinary TAP levels also peaked at 24 h post-trauma and subsequently decreased (P<0.05). At 72 h post-trauma, the pancreatic cells were loosely distributed, with damaged acini, hyperchromatic nuclei and severe inflammatory cell invasion. These results indicated that the Beagle model of grade III PT was satisfactorily established, and that CEUS is potentially useful as an auxiliary diagnosis method for PT. This animal model may be useful for studying the pathogenesis, disease progress and complications of PT.

Effects of Calcium Channel Blockers on Trypsinogen Activation and Severity of Cerulein-induced Acute Pancreatitis in Rats

Acute pancreatitis is an inflammatory disease of the pancreas associated with high mortality but without a specific therapy. Intrapancreatic protease activation appears to be an early event in the development of acute pancreatitis but its association with pathogenesis has not been established. Recently it has been demonstrated that an enormous rise in the cytoplasmic Ca2+ levels of pancreatic acinar cells could be associated with the development of acute pancreatitis, thereby suggesting that Ca2+ channel could be a potential target for treatment. In this study, the protective effects of calcium channel blockers such as 2-aminoethoxydiphenyl borate, dantrolene and verapamil were investigated in cerulein-induced acute pancreatitis in vivo. Rats were divided into five groups. Group 1 (control), group 2 (cerulein, 100 µg/kg), group 3 (cerulein+ 2-aminoethoxydiphenyl borate, mg/kg), group 4 (cerulein+dantrolene, 10 mg/kg) and group 5 (cerulein+verapamil, 2.5 mg/kg). Activities of amylase, lipase, cathepsin B, pancreatic secretory trypsin inhibitor and trypsin and levels of trypsinogen activation peptide and trypsinogen were measured addition to histological examination of the sections of pancreas. The results showed that cerulein increased the amylase, lipase and trypsin activities and trypsinogen activation peptide levels significantly. Administration of calcium channel blockers significantly protected the pancreas from histological damage (p<0.05). The results of this study demonstrated that calcium channel blockers can mitigate early protease activation and pancreas injury. It was suggested regulation of calcium channels would be relevant to maintain pancreatic acinar cell homeostasis and further research is necessary to understand the protective effects of calcium channel blockers.

Prior peritoneal lavage with hot 0.9 % saline induces HSP70 expression and protects against cerulein-induced acute pancreatitis in rats

Recent studies have indicated that pre-induction of heat shock protein 70 (HSP70) expression in the pancreas protects against secretagogue-induced pancreatitis. In those studies, the HSP70 was mostly induced by unfeasible conditions. The aim of this current study was to investigate the effect of peritoneal lavage with hot 0.9% saline (42°C) on the pancreatic expression of HSP70 and its protective effect on cerulein-induced acute pancreatitis in rats. Male Wistar rats were peritoneally lavaged with 0.9% saline at 42°C for 30min. HSP70 expression was evaluated by western blotting analysis. Prior peritoneal lavages with hot and warm saline were performed. Acute pancreatitis was induced by administration of intraperitoneal injection of cerulein (20μg/kg) four times, and its severity was assessed by measuring serum amylase, tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), and trypsinogen activation peptide (TAP) levels. Pancreatic sections were stained with hematoxylin and eosin for histological evaluation. Peritoneal lavage with hot 0.9% saline increased intrapancreatic HSP70 expression and ameliorated the cerulein-induced pancreatitis in rats, judged by the significantly reduced serum amylase, TNF-α, and IL-6 concentrations; histopathological scores, and serum TAP levels. Peritoneal lavage with hot 0.9% saline can induce HSP70 expression and prevent cerulein-induced acute pancreatitis in rats. The results suggest that HSP70 protects against cerulein-induced pancreatitis by preventing proinflammatory cytokine synthesis and trypsinogen activation during acute pancreatitis.

Rho‐kinase signalling regulates trypsinogen activation and tissue damage in severe acute pancreatitis

Severe acute pancreatitis (SAP) is characterized by trypsinogen activation, infiltration of leucocytes and tissue necrosis but the intracellular signalling mechanisms regulating organ injury in the pancreas remain elusive. Rho-kinase is a potent regulator of specific cellular processes effecting several pro-inflammatory activities. Herein, we examined the role of Rho-kinase signalling in acute pancreatitis. Pancreatitis was induced by infusion of taurocholate into the pancreatic duct in C57BL/6 mice. Animals were treated with a Rho-kinase inhibitor Y-27632 (0.5-5 mg·kg⁻¹) before induction of pancreatitis. Taurocholate infusion caused a clear-cut increase in blood amylase, pancreatic neutrophil infiltration, acinar cell necrosis and oedema formation in the pancreas. Levels of pancreatic myeloperoxidase (MPO), macrophage inflammatory protein-2 (MIP-2), trypsinogen activation peptide (TAP) and lung MPO were significantly increased, indicating local and systemic disease. Inhibition of Rho-kinase activity dose-dependently protected against pancreatitis. For example, 5 mg·kg⁻¹ Y-27632 reduced acinar cell necrosis, leucocyte infiltration and pancreatic oedema by 90%, 89% and 58%, respectively, as well as tissue levels of MPO by 75% and MIP-2 by 84%. Moreover, Rho-kinase inhibition decreased lung MPO by 75% and blood amylase by 83%. Pancreatitis-induced TAP levels were reduced by 61% in Y-27632-treated mice. Inhibition of Rho-kinase abolished secretagogue-induced activation of trypsinogen in pancreatic acinar cells in vitro. Our novel data suggest that Rho-kinase signalling plays an important role in acute pancreatitis by regulating trypsinogen activation and subsequent CXC chemokine formation, neutrophil infiltration and tissue injury. Thus, these results indicate that Rho-kinase may constitute a novel target in the management of SAP.

Caerulein or taurocholate induced enzymatic and histologic alterations in the isolated perfused rat pancreas

Early events in the pathogenesis of experimental acute pancreatitis are intensively studied using isolated cells or animal models. However, the results and their interpretations are dependent on the complexity of biological structures. Therefore, we proposed that studies on isolated perfused pancreas can give additional information about processes leading to acinar cell injury. This hypothesis was examined adapting the well-established caerulein hyperstimulation model and the taurocholate model of acute pancreatitis to the extracorporeal perfused isolated rat pancreas. The pancreas was removed with the duodenum including the arterial supply. A continuous perfusion of the organ was performed with a modified Krebs-Ringer bicarbonate buffer. Intraarterial caerulein application or an intraductal taurocholate (3.5%) application were used to induce acinar cell injury which was determined as the release of amylase, lipase and lactate dehydrogenase into the portal outflow medium and into the transudation fluid and by examination of histological alterations. Trypsinogen release and activation was followed by analysis of trypsinogen activation peptide (TAP) in the transudation fluid and in pancreatic tissue. Perfusion of isolated rat pancreas with supramaximal concentrations of caerulein or retrograde injection of taurocholate (3.5%) resulted in acinar cell injury indicated by elevated levels of amylase and lipase into the perfusate and into the transudation fluid. TAP levels in the transudation fluid significantly increased after perfusion with caerulein or retrograde injection of taurocholate (3.5%). The histological alterations after taurocholate application include oedema and necrosis and show significant differences to the control perfusion. Extensive pancreatic necroses were not observed after caerulein hyperstimulation. The isolated perfused rat pancreas is a useful model to investigate pathophysiological mechanisms which are relevant for the early phase of acute pancreatitis. The caerulein and the taurocholate models are transferable to the isolated rat pancreas. Studies on isolated perfused rat pancreas enable pathophysiological investigations of the exocrine pancreas without influence of systemic components, but with preserved morphology.

Dexamethasone Affects Inflammation but Not Trypsinogen Activation in Experimental Acute Pancreatitis

Background/Aims: Trypsinogen activation and inflammation are early events in acute pancreatitis. This experimental study aimed to show the effects of dexamethasone on them. Methods: Cerulein and taurocholate pancreatitis were induced in 2 groups of 12 Wistar rats each. Six animals per group were injected with dexamethasone 1 h prior to the induction of acute pancreatitis. Amylase, phospholipase A2, TNF-α, IL-6, IL-10, α2-antiplasmin in plasma and trypsinogen activation peptide (TAP) in urine were measured in healthy rats, then 0.5 and 6 h after pancreatitis induction. A severity score based on edema, necrosis and ascites was calculated at 6 h. TNF-α, IL-6 and IL-10 were measured 0.5 h after laparotomy in a control sham-operated group of 6 rats. Results: Inflammatory markers increased early in the course of both mild and severe acute pancreatitis and were significantly lowered by dexamethasone. The severity score was higher in taurocholate than in cerulein pancreatitis. It was significantly decreased by dexamethasone only in rats with mild pancreatitis. TAP remained unchanged in mild pancreatitis compared to healthy animals but increased late in the course of taurocholate pancreatitis. Trypsinogen activation was not affected by dexamethasone at all. Conclusion: Inflammation occurred earlier than the increase in urinary TAP in severe pancreatitis in rats. Dexamethasone inhibited inflammation but had no influence on TAP levels in experimental mild and severe acute pancreatitis.

Melatonin reduces pancreatic prostaglandins production and protects against caerulein‐induced pancreatitis in rats

Melatonin has been used to treat experimental pancreatitis, although not all the drug's therapeutic mechanisms of melatonin have been defined. Prostaglandins (PGs) are proinflammatory mediators that exert their effects mainly locally during inflammatory diseases. The present study was undertaken to examine whether treatment with melatonin influences local PG production. An acute pancreatitis model in male Sprague-Dawley rats (225-275 g) was established by continuously infusing caerulein (15 mg/kg/hr). Mean arterial pressure and pancreatic perfusion were monitored continuously. Melatonin was delivered via the intraperitoneal route at doses of either 2 or 10 mg/kg, 30 min after caerulein injection. Malondialdehyde and glutathione levels of the pancreas and liver and the trypsinogen activation peptide levels in the serum were measured at the end of the experiment (8 hr after infusion of caerulein). Intraperitoneal injection of melatonin (2 and 10 mg/kg) reduced the reduction in systemic arterial pressure and decreased pancreatic perfusion in the rat model of caerulein pancreatitis. Moreover, melatonin treatment changed local PG production toward control level. Higher dose of melatonin was somewhat more effective in preventing the caerulein-induced alterations than was the lower dose.

Transgenic expression of pancreatic secretory trypsin inhibitor-I ameliorates secretagogue-induced pancreatitis in mice

Endogenous trypsin inhibitors are believed to inhibit protease activity if trypsin becomes inadvertently activated within the acinar cell. However, this action remains unproven, and the role of endogenous pancreatic trypsin inhibitors in acute pancreatitis is unknown. In this study, we tested whether increased levels of pancreatic secretory trypsin inhibitor-I (PSTI-I) in mice could prevent secretagogue-induced pancreatitis. Rat PSTI-I expression was targeted to pancreatic acinar cells in transgenic mice by creating a minigene driven by the rat elastase I enhancer/promoter. Secretagogue-induced pancreatitis was achieved by 12 hourly intraperitoneal injections of caerulein. The severity of pancreatitis was assessed by measurements of serum amylase, histologic grading, and pancreas wet weight-to-body weight ratio. Trypsinogen activation and trypsin activity were measured in pancreatic extracts. Targeted expression of PSTI-I to the pancreas increased endogenous trypsin inhibitor capacity by 190% (P <.01) in transgenic vs. nontransgenic mice. Caerulein administration to nontransgenic mice produced histologic evidence of acute pancreatitis, and significantly elevated serum amylase and pancreas weight ratio. In caerulein-treated transgenic mice, the histologic severity of pancreatitis was significantly reduced. There was no difference in trypsinogen activation peptide levels between caerulein-treated transgenic and nontransgenic mice. However, trypsin activity was significantly lower in transgenic mice receiving caerulein compared with nontransgenic mice. These data demonstrate that the severity of secretagogue-induced pancreatitis is significantly ameliorated in mice with higher pancreatic levels of trypsin inhibitor. We propose that PSTI-I prevents pancreatitis by inhibiting the activity of trypsin, rather than by reducing trypsinogen activation.

Clinical value of rapid urine trypsinogen-2 test strip, urinary trypsinogen activation peptide, and serum and urinary activation peptide of carboxypeptidase B in acute pancreatitis

To assess the usefulness of urinary trypsinogen-2 test strip, urinary trypsinogen activation peptide (TAP), and serum and urine concentrations of the activation peptide of carboxypeptidase B (CAPAP) in the diagnosis of acute pancreatitis. Patients with acute abdominal pain and hospitalized within 24 h after the onset of symptoms were prospectively studied. Urinary trypsinogen-2 was considered positive when a clear blue line was observed (detection limit 50 microg/L). Urinary TAP was measured using a quantitative solid-phase ELISA, and serum and urinary CAPAP by a radioimmunoassay method. Acute abdominal pain was due to acute pancreatitis in 50 patients and turned out to be extrapancreatic in origin in 22 patients. Patients with acute pancreatitis showed significantly higher median levels of serum and urinary CAPAP levels, as well as amylase and lipase than extrapancreatic controls. Median TAP levels were similar in both groups. The urinary trypsinogen-2 test strip was positive in 68% of patients with acute pancreatitis and 13.6% in extrapancreatic controls (P<0.01). Urinary CAPAP was the most reliable test for the diagnosis of acute pancreatitis (sensitivity 66.7%, specificity 95.5%, positive and negative predictive values 96.6% and 56.7%, respectively), with a 14.6 positive likelihood ratio for a cut-off value of 2.32 nmol/L. In patients with acute abdominal pain, hospitalized within 24 h of symptom onset, CAPAP in serum and urine was a reliable diagnostic marker of acute pancreatitis. Urinary trypsinogen-2 test strip showed a clinical value similar to amylase and lipase. Urinary TAP was not a useful screening test for the diagnosis of acute pancreatitis.

Serum Trypsinogen Activation Peptide in the Assessment of the Diagnosis and Severity of Acute Pancreatic Damage

To evaluate the clinical value of a new direct and competitive immunoassay for trypsinogen activation peptide (TAP) determination in acute pancreatitis (AP). The subjects were 34 patients with AP (22 mild, 12 severe), 12 patients with nonpancreatic acute abdominal pain (AA), 11 healthy subjects (HS), and 16 consecutive patients who underwent therapeutic ERCP (ERCP). Serum TAP, amylase, and lipase levels were determined in AP, AA, and HS at their initial observation; the AP patients were also studied for 6 consecutive days after admission. In the ERCP patients, serum TAP, amylase, and lipase levels, as well as urine TAP and amylase levels, were determined before and 6 hours after endoscopy. Serum TAP levels on admission were 0.35 +/- 1.60 OD (mean +/- SD) in AP patients and 0.005 +/- 0.001 OD in AA patients, while HS patients had no detectable serum TAP levels. ERCP patients had no detectable serum TAP levels before and 6 hours after the ERCP, whereas urine TAP concentrations were 1.72 +/- 3.43 OD and 0.75 +/- 1.49 OD before and 6 hours after the execution of the endoscopy, respectively (P = 0.249). The sensitivities and specificities of serum TAP, amylase, and lipase levels in discriminating between AP and AA were 23.5% and 91.7%, 94.1% and 100%, and 97.1% and 100%, respectively, while those used in the assessment of the severity of AP were 29.9% and 73.5%, 38.8% and 81.2%, and 28.4% and 83.6%, respectively. TAP is of limited value in assessing the diagnosis and the severity of acute pancreatic damage.

Endothelin(A) receptor blockade reduces ischemia/reperfusion injury in pig pancreas transplantation.

The effect of prophylactic administration of a selective endothelin(A) receptor antagonist (ET(A)-RA) on ischemia/reperfusion injury in an experimental model of graft pancreatitis after pancreas transplantation was evaluated. It is well established that endothelin-1 (ET-1), a powerful vasoconstrictor, plays an important role in the development of pancreatitis. Recent studies have shown a beneficial effect of endothelin receptor antagonists in the therapy for experimental pancreatitis. Relevant ischemia/reperfusion injury was induced in pig pancreas transplants after 6 hours hypothermic preservation in University of Wisconsin solution. The recipients were randomized into 2 groups: control pigs received isotonic saline and the treated group received the selective ET(A)-RA BSF 208075 at the beginning of reperfusion. On postoperative days 2 and 5, animals were relaparotomized to obtain tissue specimens. Blood monitoring included lipase, amylase, C-reactive protein, trypsinogen-activation peptide, thiobarbituric acid-reacting substances, and ET-1. Partial oxygen tension (p(ti)O(2)) was measured by a Clarke-type electrode and blood flow by laser doppler. A semiquantitative score index was used for assessment of histologic injury and for immunohistochemical analysis of ET-1 and ET(A) receptor expression. Tissue mRNA levels of prepro ET-1, ET(A) receptor, pro-interleukin (IL)-6, and pro-IL-1beta were quantified using TaqMan real-time reverse transcription-polymerase chain reaction (RT-PCR). Prophylactic treatment with ET(A)-RA significantly reduced the severity of graft pancreatitis evidenced by C-reactive protein. The finding of transient capillary perfusion at the beginning of reperfusion supports the application of the ET(A)-RA during this period. The dramatic increase of plasma ET-1 in the therapy group is a clear evidence of effective receptor blockade. Mean trypsinogen-activation peptide levels from the portal venous effluent, but not mean systemic plasma TAP values were significantly lower in the treated group. Analysis of p(ti)O(2) and blood flow revealed a significant improvement of capillary perfusion and blood flow in the treated group and was associated with relevant reduction of tissue injury. Intrapancreatic ET-1 and IL-6 mRNA expression and ET-1 protein levels were significantly lower in the therapy group as compared with the control group. In contrast, ET(A) mRNA showed a marked up-regulation by ET(A) receptor blockade. Application of a ET(A)-RA reduces ischemia/reperfusion induced graft pancreatitis in a pig transplantation model by improving microcirculation and reducing tissue injury.

Mechanism of kinin release during experimental acute pancreatitis in rats: evidence for pro- as well as anti-inflammatory roles of oedema formation.

1 Kinin B(2) receptor antagonists or tissue kallikrein (t-KK) inhibitors prevent oedema formation and associated sequelae in caerulein-induced pancreatitis in the rat. We have now further investigated the mechanism of kinin generation in the pancreas. 2 Kinins were elevated in the pancreatic tissue already before oedema formation became manifest. Peak values (421+/-59 pmol g(-1) dry wt) were reached at 45 min and remained elevated for at least 2 h; a second increase was observed at 24 h. Pretreatment with the B(2) receptor antagonist icatibant abolished kinin formation, while post-treatment was ineffective. 3 Total kininogen levels were very low in the pancreas of controls, but increased 75-fold during acute pancreatitis. This increase was absent in rats that were pretreated with icatibant. 4 During pancreatitis, t-KK-like and plasma kallikrein (p-KK)-like activity in the pancreas, as well as trypsinogen activation peptide (TAP) increased significantly. Icatibant pretreatment further augmented t-KK about 100-fold, while p-KK was significantly attenuated; TAP levels remained unaffected. 5 Endogenous protease inhibitors (alpha(1)-antitrypsin, alpha(2)-macroglobulin) were low in normal tissues, but increased 45- and four-fold, respectively, during pancreatitis. This increase was abolished when oedema formation was prevented by icatibant. 6 In summary, oedema formation is initiated by t-KK; the ensuing plasma protein extravasation supplies further kininogen and active p-KK to the tissue. Concomitantly, endogenous protease inhibitors in the oedema fluid inhibit up to 99% of active t-KK. Our data thus suggest a complex interaction between kinin action and kinin generation involving positive and negative feedback actions of the inflammatory oedema.

Influence of pancreatic enzyme content on experimental acute pancreatitis.

Some studies demonstrate the crucial role of proteases in the pathogenesis of acute pancreatitis (AP). Systemic release of proinflammatory cytokines such as tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) has been demonstrated in AP, yet the mechanism of activation remains unclear. Furthermore, it is not known if the amount of pancreatic enzyme in the pancreas determines the production of proinflammatory cytokines. To determine whether there is a link between the pancreatic enzyme content and the production of cytokines and consequently the systemic lesions observed in AP. Forty-seven animals were divided into three groups: group I had a high pancreatic enzyme level (with and without AP), group II had a low pancreatic enzyme level (cerulein infusion: 0.133 microg x kg(-1) x h(-1)) (with and without AP), and group III were the controls. AP was induced by injection of 5% sodium taurocholate into the pancreatic duct. To evaluate the pancreatic enzyme contents before AP, trypsinogen and amylase analysis was carried out on pancreatic tissue collected after the animals were killed. Two hours after induction of AP, concentrations of pancreatic enzymes and trypsinogen activation peptide (TAP) in serum, ascitic fluid, and pancreatic tissue were determined. The ascitic fluid was assayed for TNF-alpha and the serum was assayed for IL-6 with ELISA kits. Systemic lesions were sought on the basis of hepatic mitochondrial respiratory function measured polarographically. The administration of physiological doses of cerulein diminishes the pancreatic enzyme and TAP levels, the production of proinflammatory cytokines, and the liver mitochondrial dysfunction observed in AP, suggesting that the pancreatic enzyme content is an important factor in the severity of AP.

Modulation of endogenous nitric oxide synthase in experimental acute pancreatitis: role of anti-ICAM-1 and oxygen free radical scavengers.

To evaluate, in an experimental model of acute pancreatitis, the impact of nitric oxide on the disease process and the interaction between nitric oxide and oxygen free radicals. Nitric oxide and oxygen free radicals are involved in the pathophysiology of acute pancreatitis. It is well established that oxygen free radicals play an important role in the development of pancreatic cell damage and remote organ failure, but the impact of nitric oxide on the disease process and the interactions between the two radical species remain controversial. Necrotizing pancreatitis (NP) was induced in Wistar rats by intraductal sodium taurocholate infusion after pretreatment with isotonic saline (NP-S), superoxide dismutase/catalase (NP-SOD/CAT), or an anti-ICAM-1 antibody (aICAM-1). Sham-operated rats received isotonic saline (SHX). After an observation period of 5 minutes and 24 hours, the pancreas was removed for microscopy, glutathione, and myeloperoxidase (MPO) analysis. The inducible NO synthase (NOS-2) was detected by Western blotting or RT-PCR. Serum was analyzed for nitrite/nitrate (NO2-/NO3-) and S-nitrosothioles (RSNO), while plasma was used to assay for trypsinogen activation peptides (TAP). NP-S animals showed a significant decrease in GSH levels after NP-induction as compared with animals under therapy. Increased MPO levels in the NP-S group were significantly reduced by aICAM-1 while SOD/CAT injection showed no changes. Serum NO-derivatives peaked at 12 hours while TAP levels had a maximum at 6 hours after NP induction, and were lower after aICAM-1 application SOD/CAT treatment increased both parameters. Extended acinar cell damage and inflammatory infiltrate developed in NP-S animals and was significantly improved by SOD/CAT and aICAM-1 treatment. RT-PCR and Western-blot analysis revealed NOS-2 expression in the NP-S group, which was reduced by radical scavengers and aICAM-1. Enhanced nitric oxide synthase expression and increased nitric oxide derivatives are found during severe acute pancreatitis. Oxygen free radicals and neutrophils seem to be potent and important regulation mechanisms for nitric oxide synthase activity and nitric oxide-mediated toxicity but imply only a secondary role for nitric oxide in the local pathologic mechanism of this disease.

Urinary Excretion of Trypsinogen Activation Peptide (TAP) in Taurocholate-Induced Pancreatitis in Rats

Trypsinogen activation peptide (TAP) is a useful marker of severe acute pancreatitis. However, it is sometimes difficult to detect an elevation of plasma TAP in patients with acute pancreatitis because TAP is rapidly cleared from plasma. Therefore, urine TAP has been evaluated to provide an accurate prediction of the outcome of pancreatitis. In the present study, we examined the time course of plasma and urine TAP simultaneously after induction of taurocholate-induced pancreatitis in rats. Plasma TAP levels peaked at 1 hour after the induction of pancreatitis and then gradually decreased, but was still higher than prepancreatitis levels at 48 hours. Significant increases in urine TAP levels were seen at 0-6, 6-12, and 30-36 hours after induction of pancreatitis. The peak level of urine TAP output and TAP/creatinine ratio was observed at 6-12 and 30-36 hours, respectively. Urine TAP concentration showed a significant correlation with both urine TAP/creatinine ratio and TAP output in urine (p < 0.01). In conclusion, plasma TAP increased immediately after the induction of pancreatitis, but excretion of TAP into urine was delayed several hours in taurocholate-induced pancreatitis in rats. The measurement of urine TAP concentration alone sufficiently can reflect the amount of TAP liberated in the pancreas at initial stage of acute pancreatitis.

Do plasma and urine trypsinogen activation peptides (TAP) really increase in trypsin-taurocholate-induced pancreatitis?

Plasma and urine levels of trypsinogen activation peptides (TAP) reflect the severity of acute pancreatitis in experimental and clinical acute pancreatitis. In trypsin-taurocholate-induced pancreatitis in rats, the extrinsic bovine trypsin used for the induction of pancreatitis might influence on the TAP levels after induction of pancreatitis. The aim of the present study was to elucidate whether infused trypsin itself affects TAP levels in trypsin-taurocholate-induced pancreatitis. Rats were divided into three groups. In the pancreatitis group, acute pancreatitis was induced by a retrograde infusion of bovine trypsin and sodium taurocholate into the pancreatic duct. In the duct infusion group and peritoneal injection group, a mixture of bovine trypsin and trypsin inhibitor, ONO-3403, was infused into the pancreatic duct or the peritoneal cavity. Plasma and urine TAP concentration significantly increased in trypsin-taurocholate-induced pancreatitis but not in the duct infusion and peritoneal injection groups for 6 hours after the infusion of trypsin. Serum rat immunoreactive trypsin (IRT) and amylase significantly increased in the pancreatitis and duct infusion groups but not in the peritoneal injection group. Serum levels of bovine IRT in the pancreatitis group was significantly lower than those in duct infusion and peritoneal injection groups. In conclusion, an intraductal infusion of bovine trypsin itself into pancreatic duct does not influence the levels of plasma and urine TAP in trypsin-taurocholate-induced pancreatitis.

Effects of timing of diatrizoate (water-soluble contrast medium) administration on pancreatic microcirculatory derangement in cerulein pancreatitis in rats.

We investigated whether the timing of administration of contrast medium after onset of acute pancreatitis is critical in determining the magnitude of microcirculatory derangement. An acute pancreatitis model in male Sprague-Dawley rats (225-275 g) was established by continuous infusion of cerulein (15 mg/kg per hour). The mean arterial pressure was monitored continuously by means of a femoral artery catheter. Diatrizoate (Hypaque-76), a water-soluble contrast medium, was delivered through a femoral vein catheter at doses corresponding to those given to humans, either 1, 2, or 3 hours after pancreatitis induction. In vivo microscopy and laser-Doppler flowmetry were used to investigate microcirculatory derangement. The water contents of the pancreas and lung, the malondialdehyde levels of the pancreas, and the trypsinogen activation peptide levels in the serum were measured at the end of the experiment (8 hours after infusion of cerulein). Early administration of contrast medium (1 hour after pancreatitis induction) resulted in significantly greater changes in microcirculation and mean arterial pressure than did late administration (2 or 3 hours after pancreatitis induction). Rats given contrast medium 1 hour after induction also had highest pancreas and lung water contents, the highest pancreas malondialdehyde levels, and the highest serum trypsinogen activation peptide levels. These results show that a water soluble contrast medium that is often used for computed tomographic imaging of the pancreas can adversely affect the pancreatic microcirculatory parameters, such as tissue perfusion and leukocyte sticking, and hemodynamics in a cerulein-induced model of acute pancreatitis. Early administration seems to cause more severe derangement of the pancreatic microcirculation.

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

To evaluate the effect of a new endothelin receptor antagonist (ET-RA) on the course of severe experimental pancreatitis. Endothelin-1 has been shown to reduce regional blood flow in various organs, including the pancreas, and to aggravate cerulein-induced mild pancreatitis. 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. 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. Therapy with the new ET-RA reduces the early mortality rate in experimental ANP, probably by reducing fluid sequestration and improving microcirculation.

Effect of different immunosuppressive agents on acute pancreatitis: a comparative study in an improved animal model.

Immunosuppressive drugs have been associated with the development and progression of acute pancreatitis after organ transplantation. Consequently, a reduction or a change in immunosuppressive therapy has been recommended once posttransplantation pancreatitis has been suspected. However, it is not known which of the available immunosuppressive agents is most harmful to the pancreas and which may be used safely in this situation. The objective of this study was to investigate the effect of different immunosuppressive drugs in various dosages on intrapancreatic protease activation, acinar cell necrosis, and mortality in an improved model of acute necrotizing pancreatitis in the rat. The rat model of acute necrotizing pancreatitis, like posttransplantation pancreatitis, is characterized by ischemia and microcirculatory disorders. Acute pancreatitis was induced in rats by using a combination of low-dose controlled intraductal glycodeoxycholic acid superimposed on intravenous cerulein hyperstimulation. Six hours thereafter, animals were randomized to intravenous therapy with 2, 10, or 50 mg/kg/day prednisolone (PRED); 3, 15, or 60 mg/kg/day cyclosporine A (CsA); 10 mg/kg/day azathioprine (AZA); 0.6 mg/kg/day orthoclone OKT3 (OKT3); or saline. After 36 hr, surviving animals were killed to determine acinar cell necrosis and trypsinogen activation peptides levels (TAP) in blood and ascites. Compared with saline-treated control rats, animals treated with 60 mg/kg/day CsA developed significantly more acinar cell necrosis and had increased amounts of TAP in ascites. Likewise, there was more extensive acinar cell necrosis in animals subjected to AZA therapy. However, this was not associated with incremental TAP. Animals treated with 3 or 15 mg/kg/day CsA, OKT3, or PRED showed no significant changes in these target parameters. Animals given 10 or 50 mg/kg/day PRED even had decreased hematocrit values and produced significantly less ascites than animals in the other groups. The present results suggest that AZA and high doses of CsA aggravate acute pancreatitis and should, therefore, be avoided once posttransplantation pancreatitis has been suspected, whereas lower doses of CsA, OKT3, and PRED may be used safely. PRED can even be used at higher doses as may be required when graft rejection is suspected.

Elevated calcium and activation of trypsinogen in rat pancreatic acini

Background—Acute pancreatitis associated with hypercalcaemia has been described in humans and experimental animals. It has been demonstrated that calcium dose dependently accelerates trypsinogen activation, and it is generally believed that...