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

Therapy Effect of the Stable Gastric Pentadecapeptide BPC 157 on Acute Pancreatitis as Vascular Failure-Induced Severe Peripheral and Central Syndrome in Rats

We revealed the therapy effect of the stable gastric pentadecapeptide BPC 157 (10 μg/kg, 10 ng/kg ig or po) with specific activation of the collateral rescuing pathways, the azygos vein, on bile duct ligation in particular, and acute pancreatitis as local disturbances (i.e., improved gross and microscopy presentation, decreased amylase level). Additionally, we revealed the therapy’s effect on the acute pancreatitis as vascular failure and multiorgan failure, both peripherally and centrally following “occlusion-like” syndrome, major intoxication (alcohol, lithium), maintained severe intra-abdominal hypertension, and myocardial infarction, or occlusion syndrome, and major vessel occlusion. The application-sacrifice periods were ligation times of 0–30 min, 0–5 h, 0–24 h (cured periods, early regimen) and 4.30 h–5 h, 5 h–24 h (cured periods, delayed regimen). Otherwise, bile duct-ligated rats commonly presented intracranial (superior sagittal sinus), portal and caval hypertension and aortal hypotension, gross brain swelling, hemorrhage and lesions, heart dysfunction, lung lesions, liver and kidney failure, gastrointestinal lesions, and severe arterial and venous thrombosis, peripherally and centrally. Unless antagonized with the key effect of BPC 157 regimens, reversal of the inferior caval and superior mesenteric vein congestion and reversal of the failed azygos vein activated azygos vein-recruited direct delivery to rescue the inferior-superior caval vein pathway; these were all antecedent to acute pancreatitis major lesions (i.e., acinar, fat necrosis, hemorrhage). These lesions appeared in the later period, but were markedly attenuated/eliminated (i.e., hemorrhage) in BPC 157-treated rats. To summarize, while the innate vicious cycle may be peripheral (bile duct ligation), or central (rapidly developed brain disturbances), or peripheral and central, BPC 157 resolved acute pancreatitis and its adjacent syndrome.

Effect of Aggressive Fluid Therapy on Outcomes after Endoscopic Retrograde Cholangiopancreatography: A Randomized Controlled Clinical Trial

BACKGROUND Pancreatitis is a serious complication of endoscopic retrograde cholangiopancreatography (ERCP), which may lead to death. The purpose of this study was to evaluate the preventive effect of aggressive fluid therapy on the incidence of post-ERCP pancreatitis. METHODS In double-blind controlled condition, 240 patients were selected and divided into two groups. The treatment of the intervention group (n = 120) included a dose of 20 mL/kg of ringer lactate infusion within 90 minutes before ERCP and 3 mL/kg/h during ERCP followed by 3 mL/kg/h up to 8 hours. The treatment of the control group (n = 120) included a dose of 1.5 mL/kg of ringer lactate infusion during ERCP up to 8 hours later. Firstly, the patients were evaluated in terms of excessive fluid and serum amylase and pain level, and then they were re-evaluated 2, 8, and 24 hours after ERCP. RESULTS The mean age of the patients was 51.57 ± 13.5 years. Most of the patients were female (54.5%). Pancreatitis was developed in 26 patients including 5.83% of the patients in the intervention group and 15.83% of the patients in the control group (p = 0.013). Pancreatic pain was seen in 7.5% of the patients in the intervention group and in 27.5% of the control group (p < 0.005). Hyperamylasemia was seen in 20.83% of the patients in the intervention group and in 35% of the control group (p = 0.014). The mean days of hospital admission was 1.308 ± 0.807 in the intervention group and 1.425 ± 0.876 in the control group (p = 0.275). CONCLUSION Aggressive fluid therapy with ringer lactate solution before ERCP can effectively prevent postERCP pancreatitis, pancreatic pain, and hyperamylasemia.

Translational Research for Acute Pancreatitis - Which Results Have Really Influenced Our Therapy?

Acute pancreatitis is a common disease characterized by acinar cell destruction and acute inflammatory changes of the pancreas that lead to a systemic inflammatory response. A major research effort has been undertaken to unravel the underlying pathophysiology and to identify possible therapeutic targets. Still, only very few findings have influenced our clinical practice in the treatment of acute pancreatitis. Pancreatic microcirculation and capillary blood flow have long been suspected to play a major role in the course of the disease. It therefore seemed tempting to speculate that manipulation of the vasoconstrictor endothelin or its antagonist nitrogen monoxide could positively influence the outcome. We had to acknowledge, however, that these mechanisms take place very early in the disease course and that only prophylactic applications show an effect; this is useful in the setting of pancreas transplantation and endoscopic retrograde cholangiopancreatography but not applicable for clinical use in the therapy of acute pancreatitis. Research then focused on later pathophysiological stages of the disease, mainly on the process of adhesion and extravasation of leukocytes into the pancreatic tissue. Here, integrins and adhesion molecules like the intercellular adhesion molecule-1 (ICAM-1) were investigated in detail. A monoclonal antibody to ICAM-1 showed promising results in experimental models but was never further evaluated in the clinical setting. Hemodilution and fluid resuscitation was recognized to be an important therapeutic tool in acute pancreatitis. Here, initial experimental studies favored colloid solutions, and especially dextrans for isovolemic fluid resuscitation. It was recognized only later that colloid solutions are not effective and may even increase mortality in critically ill patients. Therefore, goal-directed infusion of Ringer's lactate solution at a moderate infusion rate to optimize volume status and hemoconcentration in acute pancreatitis is now advocated. In summary, out of the numerous experimental and translational studies, only very few have really influenced our daily clinical practice. Further research is therefore needed to find more specific and effective therapeutic agents for the treatment of acute pancreatitis.

Evaluation of local instillation of antibiotics in infected walled-off pancreatic necrosis

BACKGROUND

Infected walled-off pancreatic necrosis (WON) is associated with increased morbidity and mortality. Systemic antibiotics are the main treatment, but are associated with adverse reactions and risk of superinfections. This study evaluates the efficacy of local instillation of antibiotics into WON.

METHODS

We performed a retrospective cohort study of all consecutive patients with infected WON, who were treated with endoscopic transmural drainage and necrosectomy (ETDN) at a tertiary referral hospital between 2012 and 2016. A total of 91 patients were included. Patients often received concomitant intravenous and local antibiotics. Local antibiotics were added to the irrigation fluid depending on microbiological findings. A beneficial response was defined as the eradication of a microbe on subsequent culturing. Univariable and multivariable logistic regression analyses were used to evaluate antimicrobial efficacy.

RESULTS

At the first drainage 81 (86%) patients had infected and 10 sterile WON. Among patients with bacterial infections, neither local nor systemic antibiotics were associated with the eradication of microbes between first and second culture. Between the second and third culture, the use of local antibiotics was associated with the eradication of microbes (OR, 2.54; 95% CI, 1.25-5.18; p = 0.01), but not systemic antibiotics (OR, 0.75; 95% CI, 0.38-1.38; p = 0.33). Twelve patients had fungal infections treated with local amphotericin B between first and second culture. The fungus was eradicated in all 12 patients.

CONCLUSION

Local instillation of antibiotics may be a promising supplement to systemic administration.

Serum Concentrations of Angiopoietin-2 and Soluble fms-Like Tyrosine Kinase 1 (sFlt-1) Are Associated with Coagulopathy among Patients with Acute Pancreatitis

In severe acute pancreatitis (SAP), systemic inflammation leads to endothelial dysfunction and activation of coagulation. Thrombotic disorders in acute pancreatitis (AP) include disseminated intravascular coagulation (DIC). Recently, angiopoietin-2 and soluble fms-like tyrosine kinase 1 (sFlt-1) were proposed as markers of endothelial dysfunction in acute states. Our aim was to assess the frequency of coagulation abnormalities in the early phase of AP and evaluate the relationships between serum angiopoietin-2 and sFlt-1 and severity of coagulopathy. Sixty-nine adult patients with AP were recruited: five with SAP, 15 with moderately severe AP (MSAP) and 49 with mild AP. Six patients were diagnosed with DIC according to International Society on Thrombosis and Haemostasis (ISTH) score. All patients had at least one abnormal result of routine tests of hemostasis (low platelet count, prolonged clotting times, decreased fibrinogen, and increased D-dimer). The severity of coagulopathy correlated with AP severity according to 2012 Atlanta criteria, bedside index of severity in AP and duration of hospital stay. D-dimers correlated independently with C-reactive protein and studied markers of endothelial dysfunction. Angiopoietin-2, D-dimer, and ISTH score were best predictors of SAP, while sFlt-1 was good predictor of MSAP plus SAP. In clinical practice, routine tests of hemostasis may assist prognosis of AP.

The Interplay between Inflammation, Coagulation and Endothelial Injury in the Early Phase of Acute Pancreatitis: Clinical Implications

Acute pancreatitis (AP) is an inflammatory disease with varied severity, ranging from mild local inflammation to severe systemic involvement resulting in substantial mortality. Early pathologic events in AP, both local and systemic, are associated with vascular derangements, including endothelial activation and injury, dysregulation of vasomotor tone, increased vascular permeability, increased leukocyte migration to tissues, and activation of coagulation. The purpose of the review was to summarize current evidence regarding the interplay between inflammation, coagulation and endothelial dysfunction in the early phase of AP. Practical aspects were emphasized: (1) we summarized available data on diagnostic usefulness of the markers of endothelial dysfunction and activated coagulation in early prediction of severe AP; (2) we reviewed in detail the results of experimental studies and clinical trials targeting coagulation-inflammation interactions in severe AP. Among laboratory tests, d-dimer and angiopoietin-2 measurements seem the most useful in early prediction of severe AP. Although most clinical trials evaluating anticoagulants in treatment of severe AP did not show benefits, they also did not show significantly increased bleeding risk. Promising results of human trials were published for low molecular weight heparin treatment. Several anticoagulants that proved beneficial in animal experiments are thus worth testing in patients.

Effects of hydroxyethyl starch and cell-free hemoglobin on microcirculation, tissue oxygenation, and survival in severe acute porcine pancreatitis: results of a randomized experimental trial

OBJECTIVE

Severe acute pancreatitis is a life-threatening disease with a high mortality; so far, no causal treatment is known. The aim of this study was to evaluate the therapeutic potential of hydroxyethyl starch (HES) and cell-free hemoglobin in an experimental model.

METHODS

Thirty-nine pigs were randomly assigned into 3 groups. Severe acute pancreatitis was induced by intraductal injection of glycodeoxycholic acid in combination with intravenous administration of cerulein. All animals were kept in isovolemic conditions by application of Ringer solution, 10% HES, or cell-free hemoglobin. The pancreatic microcirculation was evaluated over 8 hours. Thereafter, the animals were observed for 6 days followed by killing of the animals and histopathologic examination.

RESULTS

The administration of HES and cell-free hemoglobin led to improved microcirculation and tissue oxygenation compared with the Ringer's group. Consequently, the histopathologic damage was reduced (5.5 [3-8.5] vs 9.5 [7.5-11]; P < 0.001). In addition, the mean survival was significantly longer at 121 hours (95% confidence interval, 102-139) versus the Ringer group's 57 hours (95% confidence interval, 32-82; P < 0.001).

CONCLUSIONS

The administration of HES and cell-free hemoglobin can improve microcirculation in severe acute porcine pancreatitis, with consequent reduction in histopathologic damage and mortality. Therefore, this might represent an interesting therapeutic option in the treatment of severe acute pancreatitis.

Effects of thoracic epidural anesthesia on survival and microcirculation in severe acute pancreatitis: a randomized experimental trial

Introduction

Severe acute pancreatitis is still a potentially life threatening disease with high mortality. The aim of this study was to evaluate the therapeutic effect of thoracic epidural anaesthesia (TEA) on survival, microcirculation, tissue oxygenation and histopathologic damage in an experimental animal model of severe acute pancreatitis in a prospective animal study.

Methods

In this study, 34 pigs were randomly assigned into 2 treatment groups. After severe acute pancreatitis was induced by intraductal injection of glycodesoxycholic acid in Group 1 (n = 17) bupivacaine (0.5%; bolus injection 2 ml, continuous infusion 4 ml/h) was applied via TEA. In Group 2 (n = 17) no TEA was applied. During a period of 6 hours after induction, tissue oxygen tension (tpO₂) in the pancreas and pancreatic microcirculation was assessed. Thereafter animals were observed for 7 days followed by sacrification and histopathologic examination.

Results

Survival rate after 7 days was 82% in Group 1 (TEA) versus 29% in Group 2: (Control) (P <0.05). Group 1 (TEA) also showed a significantly superior microcirculation (1,608 ± 374 AU versus 1,121 ± 510 AU; P <0.05) and tissue oxygenation (215 ± 64 mmHg versus 138 ± 90 mmHG; P <0.05) as compared to Group 2 (Control). Consecutively, tissue damage in Group 1 was reduced in the histopathologic scoring (5.5 (3 to 8) versus 8 (5.5 to 10); P <0.05).

Conclusions

TEA led to improved survival, enhanced microcirculatory perfusion and tissue oxygenation and resulted in less histopathologic tissue-damage in an experimental animal model of severe acute pancreatitis.

Development of a rat model of severe acute pancreatitis-associated lung injury

AIM: To establish a rat model of severe acute pancreatitis (SAP)-associated lung injury (LI) by occluding the head of the pancreas.

METHODS: Two hundred and ten rats were randomly and equally divided into a control group, a sham-operated group, and a SAP-LI model group. Rats in each group was further divided into seven subgroups for testing at 0, 6, 12, 18, 24, 36, and 48 h (n = 10 for each). The SAP-LI model group underwent occlusion of the head of the pancreas with vessel forceps. The sham-operated group underwent a surgical procedure similar to the SAP-LI model group but the head of the pancreas was not occluded. The control group only underwent anesthetization for 3 h. Blood, pulmonary alveolar lavage fluid, lung tissue and pancreatic tissue samples were collected at various time points. The level of serum amylase, content of serum proteins, percentage of polymorphonuclear neutrophils, wet/dry weight ratio of lung tissue, and content of proteins in pulmonary alveolar lavage fluid were determined. Pathological changes in lung and pancreatic tissues were observed under a light microscope.

RESULTS: All rats were live in the experiment. The level of serum amylase (5052.1 U/L ± 114.9 U/L, P < 0.01) and the percentage of polymorphonuclear neutrophils (75.2% ± 5.8%, P < 0.05) reached the peak at 12 h, and the ratio of the content of proteins in pulmonary alveolar lavage fluid to the content of serum proteins reached the peak at 36 h in the SAP-LI model group (0.009021 ± 0.000107, P < 0.01). The wet/dry weight ratio of lung tissue, reaching the minimum at 36 h in the SAP-LI mold group (1.2001 ± 0.0443, P < 0.01), differed significantly between the SAP-LI group and the other two groups (both P < 0.05). Pancreatic tissue injury became worse with the prolongation of time. LI was most serious at 36 h. Serum amylase showed a correlation with the percentage of polymorphonuclear neutrophils and wet/dry weight ratio of lung tissue (r = 0.788,P < 0.01; r = 0.365, P = 0.002). The percentage of polymorphonuclear neutrophils showed a correlation with the wet/dry weight ratio of lung tissue (r = 0.348, P = 0.003). The wet/dry weight ratio of lung tissue showed a correlation with the ratio of the content of proteins in pulmonary alveolar lavage fluid to the content of serum proteins (r = -0.717, P < 0.01). The score of pancreatic tissue pathology showed a correlation with that of lung tissue pathology (r = 0.934, P < 0.01).

CONCLUSION: A new rat model of SAP-associated LI has been successfully developed by occluding the head of the pancreas, providing an ideal model for studying the pathogenesis and treatment of this condition. LI was most serious at 36 h, which is the optimal time point for inducing SAP-associated LI.

Differential effects of endothelins on histological and ultrastructural changes and trypsinogen activation in the secretagogue-induced acute pancreatitis in rats

The role of endothelins in acute pancreatitis remains obscure. To assess the effects of endothelins (ETs) in early (4 h) caerulein-induced acute pancreatitis (AP) in rats, ET-1, ET-2 and ET-3 (0.5 or 1.0 nmol/kg) were applied twice with i.p. caerulein (2×40 μg/kg) at 1h interval. Histological and ultrastructural examinations of pancreases and the assay of trypsinogen activation in whole homogenate were performed. All ETs, especially ET-1 at the higher dose, decreased inflammatory cell infiltration despite an increase in the edema score. The vacuolization and necrosis of acinar cells were slightly increased after the lower dose of ET-1 and ET-2. Ultrastructural changes were generally improved after the higher dose of ETs. Trypsinogen activation increased from 4.8±1.3% in control to 18.4±3.8% in AP (p<0.01). It was attenuated to 6.4±1.3% (p<0.01) by the higher dose of ET-1 and to 8.8±1.5% (p<0.05) by the lower dose of ET-3. In summary, ETs, especially ET-1 at the higher dose, were found to have some beneficial effects on morphological changes and trypsinogen activation in the pancreas in early caerulein-induced AP.

Acute pancreatitis severity is exacerbated by intestinal ischemia-reperfusion conditioned mesenteric lymph

OBJECTIVE

To determine the effect of intestinal ischemia-reperfusion (IIR) on acute pancreatitis (AP) and the role of mesenteric lymph.

SUMMARY BACKGROUND DATA

Intestinal ischemia is an early feature of AP and is related to the severity of disease. It is not known whether this contributes to the severity of AP or is a consequence.

METHODS

Two experiments are reported here using intravital microscopy and a rodent model of mild acute pancreatitis (intraductal 2.5% sodium taurocholate). In the first, rats had an episode of IIR during AP that was produced by temporary occlusion of the superior mesenteric artery (30 min or 3 x 10 min) followed by 2h reperfusion. In a second study rats with AP had an intravenous infusion of mesenteric lymph collected from donor rats that had been subjected to IIR. In both experiments the pancreatic erythrocyte velocity (EV), functional capillary density (FCD), leukocyte adherence (LA), histology and edema index were measured.

RESULTS

The addition of IIR to AP caused a decline in the pancreatic microcirculation greater than that of AP alone (EV 42% of baseline vs. 73% of baseline AP alone, FCD 43% vs 72%, LA 7 fold increase vs 4 fold increase). This caused an increased severity of AP as evidenced by 1.4-1.8 fold increase of pancreatic edema index and histologic injury respectively. A very similar exacerbation of microvascular failure and increased pancreatitis severity was then demonstrated by the intravenous infusion of IIR conditioned mesenteric lymph from donor animals.

CONCLUSIONS

Unidentified factors released into the mesenteric lymph following IIR injury are capable of exacerbating AP. This highlights an important role for the intestine in the pathophysiology of AP pathogenesis and identifies mesenteric lymph as a potential therapeutic target.

Nitric oxide pathways and evidence-based perturbations in acute pancreatitis

Nitric oxide (NO) is a gaseous neurotransmitter, a vasodilator and paracrine regulator. In the pancreas, NO regulates normal pancreatic exocrine secretion, endocrine pancreatic insulin secretion and pancreatic microvascular blood flow. NO has multiple species and is produced de novo by 3 NO synthase enzymes. Endothelial NO synthase reduces the severity of the initial phase of experimental acute pancreatitis (AP). Cigarette smoking and chronic alcohol use disrupt normal NO pathways and are associated with pancreatitis and pancreatic cancer. The aims of this minireview are to describe normal intrapancreatic NO pathways, perturbations during experimental AP and due to epidemiological factors associated with pancreatic pathology, and the clinical implications of NO on AP.

Influence of Salvia miltiorrhiza on the changes of plasma endothelin and P-selectin in patients with acute pancreatitis

AIM: To explore the changes of plasma endothelin and P-selectin as well as the effects of Salvia miltiorrhiza (SM) in patients with acute pancreatitis (AP).

METHODS: A total of 82 patients with acute pancreatitis were divided into group A (n = 40) and B (n = 42), treated with general method and SM, respectively. Anther 20 normal individuals were used as normal controls. The levels of plasma endothelin (ET) and P-selectin were measured by radioimmunoassay.

RESULTS: The levels of ET and P-selectin in patients with severe acute pancreatitis (SAP) were significantly higher than those in the cases with mild acute pancreatitis (MAP) and normal controls (ET: 147.56 ± 10.65 ng/L vs 85.13 ± 9.47, 52.27 ± 6.23 ng/L, P < 0.01; P-selectin: 85.32 ± 6.21 µg/L vs 30.01 ± 4.82, 10.26 ± 2.57 µg/L, P < 0.01), and the levels of ET and P-selectin were positively correlated in SAP (r = 0.705, P < 0.01). After treatment, the levels of ET and P-selectin in group B were obviously decreased as compared with those before treatment (ET: 69.77 ± 7.65 ng/L vs 100.54 ± 11.41 ng/L, P < 0.01; P-selectin: 4.07 ± 4.75 µg/L vs 54.52 ± 9.79 µg/L, P < 0.01). The average in-hospital time of group B was distinctly shorter than that of group A (9.76 ± 1.77 d vs 14.27 ± 2.55 d, P < 0.01).

CONCLUSION: Endothelin and P-selectin may be involved in the pathogenesis of AP, and SM is effective in the treatment of AP.

Beneficial effects of vasodilators in preventing severe acute pancreatitis shock

OBJECTIVES

To investigate the effect of treatment with several vasodilatory substance on the changes in mean arterial pressure (MAP) of severe acute pancreatitis.

METHODS

Pancreatitis was induced in rats by 5% sodium taurocholate retrograde infusion through the pancreatic duct, which produces a significant decrease in arterial blood pressure.

RESULTS

Three hours after the induction of pancreatitis, a fall of approximately 25 mm Hg in MAP was observed, with no changes of MAP in untreated controls. The administration of the nitric oxide synthesis inhibitor, N-nitro-L-arginine methyl ester (25 mg/kg), previously to the induction of pancreatitis, produced a marked fall in MAP leading to the death of all the animals. When several vasodilatory substances, S-nitroso-N-acetylpenicillamine (200 microg x kg x h), calcitonin gene-related peptide (10 microg/kg), and vasoactive intestinal polypeptide (8 microg x kg x h) were administered previously to the induction of pancreatitis, the MAP fall induced by pancreatitis was not observed. The improvement of physiological conditions observed in vasodilator-treated animals is in agreement with histological data, which show only minor structural changes in the pancreas from these animals, in contrast with the severe alterations observed in untreated pancreatitic rats.

CONCLUSION

: Vasodilation confers protection against the systemic circulatory derangement derived from the development of severe acute pancreatitis.

Resveratrol: A medical drug for acute pancreatitis

Accumulating evidence demonstrates that resveratrol, a natural polyphenolic compound extracted from plants, inhibit inflammation when administered. It has direct effects on suppression of platelet coagulation and cytokines production in many experimental models. Because microcirculation occlusion and cytokines over-production is involved in many diseases such as acute pancreatitis (AP), the discovery of resveratrol as platelet and cytokines inhibitors has shed light on the treatment of AP, which still has significant mortality and morbidity. It is anticipated that this natural polyphenol could serve as a therapeutic compound in managing AP through different pathways.

Microcirculatory function and tissue damage is improved after therapeutic injection of bovine hemoglobin in severe acute rodent pancreatitis

OBJECTIVES

Stasis of the pancreatic microcirculation initiates and aggravates acute pancreatitis. Bovine hemoglobin has been shown to improve microcirculation in acute pancreatitis if prophylactically infused 15 minutes after initiation of acute pancreatitis. The purpose of this study was to evaluate the therapeutic effectiveness of bovine hemoglobin on pancreatic microcirculation and tissue damage later in the course of experimental acute rodent pancreatitis.

METHODS

In Wistar rats, severe acute pancreatitis was induced by administration of glyco-deoxycholic-acid intraductally and cerulein intravenously. Pancreatic microcirculation was continuously monitored by intravital microscopy. Three hours after the initiation of acute pancreatitis, animals received either 0.8 mL bovine hemoglobin (Oxyglobin), hydroxyethyl starch (HES), or 2.4 mL 0.9% NaCl intravenously at random. After 6 hours, animals were killed, and histopathological damage of the pancreas was assessed using a validated histology score.

RESULTS

Pancreatic microcirculation assessed by leukocyte adherence was significantly improved by the administration of bovine hemoglobin in comparison with normal saline over time (mean difference, 51.6 +/- 9.2; P < 0.001) and HES (mean difference, 24.1 +/- 9.2; P = 0.037). This result was paralleled by decreased tissue damage in the bovine hemoglobin group as opposed to NaCl (6.75 vs. 12; range, 5.25-7.75 vs. 8.25-14; P < 0.001) and HES (6.75 vs. 9; range, 5.25-7.75 vs. 7.5-10.75; P < 0.001).

CONCLUSION

Therapeutic intravenous infusion of bovine hemoglobin improves pancreatic microcirculation and reduces pancreatic tissue damage in severe acute rodent pancreatitis but is not as effective as early (prophylactic) administration.

Effect of endothelin-1 receptor antagonists on histological and ultrastructural changes in the pancreas and trypsinogen activation in the early course of caerulein-induced acute pancreatitis in rats

AIM: To assess the effect of non-selective ET_A/B (LU 302872) and selective ET_A (LU 302146) antagonist on pancreatic histology and ultrastructure of acinar cells in connection with trypsinogen activation in early caerulein-induced AP.

METHODS: Male Wistar rats with caerulein-induced AP, lasting 4 h, were treated i.p. with 10 and 20 mg/kg b.w. of each antagonist. Edema, inflammatory infiltration, necrosis and vacuolization of acinar cells in the pancreas were scored at 0-3 scale. Free active trypsin (FAT), total potential trypsin (TPT) after activation with enterokinase, and index of trypsinogen activation (%FAT/TPT) were assayed in pancreatic homogenates.

RESULTS: In untreated AP, the edema, inflammatory infiltration, necrosis and vacuolization increased as compared to control healthy rats (P<0.01). None of the treatment exerted any meaningful effect on the edema and inflammatory infiltration. The selective antagonist increased slightly the necrosis score to 0.82±0.06 at higher dose (P<0.05) vs 0.58±0.06 in untreated AP. The non-selective antagonist increased slightly the vacuolization score to 2.41±0.07 at higher dose (P<0.01) vs 1.88±0.08 in untreated AP. The decrease in the number of zymogen granules, disorganization of endoplasmic reticulum, autophagosomes and cytoplasmic vacuoles were more prominent in treated AP than in untreated AP groups. %FAT/TPT in untreated AP increased about four times (18.4±3.8 vs 4.8±1.3 in control group without AP, P<0.001). Treatment of AP with both antagonists did not affect significantly augmented trypsinogen activation.

CONCLUSION: The treatment with endothelin-1 receptors (non-selective ET_A/B and selective ET_A) antagonists has essential effect neither on the edema and inflammatory infiltration nor on trypsinogen activation observed in the early course of caerulein-induced AP. Nevertheless a slight increase of the necrosis and vacuolization score and some of the ultrastructural data could suggest the possibility of their undesired effects in caerulein-induced AP at investigated doses.

N/A

N/A

Heparin improves organ microcirculatory disturbances in caerulein-induced acute pancreatitis in rats

AIM: Microcirculatory disturbances are important early pathophysiological events in various organs during acute pancreatitis. The aim of the study was to evaluate changes in microperfusion of the pancreas, liver, kidney, stomach, colon, skeletal muscle, and to investigate the influence of heparin on the organ microcirculation in caerulein-induced experimental acute pancreatitis.

METHODS: Acute pancreatitis was induced by 4 intraperitoneal injections of caerulein (Cn) (15 μg/kg). The organ microcirculation was measured by laser Doppler flowmetry. Serum interleukin 6 and hematocrit levels were analysed.

RESULTS: Acute pancreatitis resulted in a significant drop of microperfusion in all examined organs. Heparin administration (2 ± 2.5 mg/kg) improved the microcirculation in pancreas (36.9% ± 4% vs 75.9% ± 10%), liver (56.6% ± 6% vs 75.2% ± 16%), kidney (45.1% ± 6% vs 79.3% ± 5%), stomach (65.2% ± 8% vs 78.1% ± 19%), colon (69.8% ± 6% vs 102.5% ± 19%), and skeletal muscle (59.2% ± 6% vs 77.9% ± 13%). Heparin treatment lowered IL-6 (359.0 ± 66 U/mL vs 288.558 U/mL) and hematocrit level (53% ± 4% vs 46% ± 3%).

CONCLUSION: Heparin administration has a positive influence on organ microcirculatory disturbances accompanying experimental Cn-induced acute pancreatitis.

Endothelial nitric oxide synthase is protective in the initiation of caerulein-induced acute pancreatitis in mice

The effect of inhibiting nitric oxide (NO) synthase (NOS) or enhancing NO on the course of acute pancreatitis (AP) is controversial, in part because three NOS isoforms exist: neuronal (nNOS), endothelial (eNOS), and inducible (iNOS). We investigated whether inhibition or selective gene deletion of NOS isoforms modified the initiation phase of caerulein-induced AP in mice and explored whether this affected pancreatic microvascular blood flow (PMBF). We investigated the effects of nonspecific NOS inhibition with N(omega)-nitro-l-arginine (l-NNA; 10 mg/kg ip) or targeted deletion of eNOS, nNOS, or iNOS genes on the initiation phase of caerulein-induced AP in mice using in vivo and in vitro models. Western blot analysis was performed to assess eNOS phosphorylation status, an indicator of enzyme activity, and microsphere studies were used to measure PMBF. l-NNA and eNOS deletion, but not nNOS or iNOS deletion, increased pancreatic trypsin activity and serum lipase during the initiation phase of in vivo caerulein-induced AP. l-NNA and eNOS did not affect trypsin activity in caerulein-hyperstimulated isolated acini, suggesting that nonacinar events mediate the effect of NOS blockade in vivo. The initiation phase of AP in wild-type mice was associated with eNOS Thr(495) residue dephosphorylation, which accompanies eNOS activation, and a 178% increase in PMBF; these effects were absent in eNOS-deleted mice. Thus eNOS is the main isoform influencing the initiation of caerulein-induced AP. eNOS-derived NO exerts a protective effect through actions on nonacinar cell types, most likely endothelial cells, to produce greater PMBF.

Caerulein-induced pancreatitis and islet blood flow in anesthetized rats

BACKGROUND

Microcirculatory mechanisms have been suggested to be involved in the development of acute pancreatitis. Islet blood flow has not previously been studied in this disease. The present study aimed to investigate the effects of caerulein-induced pancreatitis on pancreatic blood perfusion, especially islet blood flow.

MATERIALS AND METHODS

Continuous 4 h caerulein-infusion was used to induce mild, edemateous pancreatitis in anesthetized Sprague-Dawley rats. Some animals were then given an additional 2 h infusion of saline. Thus, at 4 or 6 h after initiating caerulein infusion the blood flow to the pancreas, pancreatic islets, and intestines was measured with a microsphere technique.

RESULTS

All infused animals demonstrated an edemateous pancreatitis, without hemorrhages. Both total pancreatic and islet blood flow was increased after the 4-h infusion. However, the increase was less pronounced in the islets. After an additional 2 h with only saline infused, the blood flow values in rats initially infused with caerulein were lower than at 4 h, but total pancreatic blood was still higher than in control rats. No effects on intestinal blood flow values were seen.

CONCLUSIONS

Pancreatic islet blood flow in rats with mild edematous pancreatitis is increased, but not to the same extent as that in the whole pancreas.