thromboxane-a2 and Pancreatitis

Topics: Acute Disease; Animals; Drainage; Epoprostenol; Intestinal Mucosa; Microcirculation; Pancreatitis; Paracentesis; Rats; Severity of Illness Index; Thromboxane A2

Acute pancreatitis (AP) is characterized by disturbances of pancreatic microcirculation. It remains unclear whether platelets contribute to these perfusion disturbances. The aim of our study was to investigate platelet activation and function in experimental AP. Acute pancreatitis was induced in rats: (1) control (n=18; Ringer's solution), (2) mild AP (n=18; cerulein), and (3) severe AP (n=18; glycodeoxycholic acid (GDOC)+cerulein). After 12 h, intravital microscopy was performed. Rhodamine-stained platelets were used to investigate velocity and endothelial adhesion in capillaries and venules. In addition, erythrocyte velocity and leukocyte adhesion were evaluated. Serum amylase, thromboxane A2, and histology were evaluated after 24 h in additional animals of each group. Results showed that 24 h after cerulein application, histology exhibited a mild AP, whereas GDOC induced severe necrotizing AP. Intravital microscopy showed significantly more platelet-endothelium interaction, reduced erythrocyte velocity, and increased leukocyte adherence in animals with AP compared to control animals. Thromboxane levels were significantly elevated in all AP animals and correlated with the extent of platelet activation and severity of AP. In conclusion, platelet activation plays an important role in acute, especially necrotizing, pancreatitis. Mainly temporary platelet-endothelium interaction is observed during mild AP, whereas severe AP is characterized by firm adhesion with consecutive coagulatory activation and perfusion failure.

Topics: Acute Disease; Amylases; Animals; Blood Flow Velocity; Blood Platelets; Cell Adhesion; Male; Microcirculation; Pancreas; Pancreatitis; Pancreatitis, Acute Necrotizing; Platelet Activation; Rats; Rats, Wistar; Thromboxane A2

Ischaemia-reperfusion (IR)-associated microcirculatory changes play a major role in acute post-transplantation pancreatitis. The pathophysiological role of platelets in these events is unknown. The aim of this study was to examine platelet adhesion and function during early reperfusion after pancreatic ischaemia.. Rats were subjected to warm pancreatic ischaemia by cross-clamping of the pancreatic vessels for 1 h. After 1 h of reperfusion, platelet-endothelium interaction was evaluated after platelet separation and staining by fluorescence microscopy. Amylase levels and pancreatic histology were evaluated 24 h after reperfusion. Animals treated according to an identical protocol, but without ischaemia, served as controls.. Mild pancreatitis had developed by 24 h after IR; serum amylase levels were significantly higher than those in control animals. The numbers of adherent platelets in capillaries and venules were significantly increased, and platelet velocity in capillaries was significantly decreased, in the IR group compared with controls. There was significantly more oedema and inflammation in pancreatic tissue after IR.. Warm ischaemia for 1 h followed by reperfusion for 24 h caused mild pancreatitis in this experimental model. The pancreatic microcirculation was characterized by pronounced platelet-endothelium interaction in capillaries and venules. These results suggest that platelet activation may play an important role in acute post-transplantation pancreatitis.

Topics: Acute Disease; Animals; Blood Platelets; Constriction; Endothelin-1; Male; Pancreas; Pancreatitis; Platelet Adhesiveness; Rats; Rats, Wistar; Reperfusion Injury; Thromboxane A2

Systemic prostacyclin and thromboxane A2 production in rat experimental acute pancreatitis has been evaluated by measuring the urinary excretion of the 2,3-dinor 6-keto prostaglandin F1 alpha and 2,3-dinor thromboxane B2, respectively. Acute pancreatitis was induced by intraductal administration of 4.5% sodium taurocholate (0.1 ml/100 mg body weight) and intravenous cerulein perfusion (5 micrograms/kg/hr) for 6 hr, respectively. Urinary excretion of 2,3-dinor 6-keto prostaglandin F1 alpha and 2,3-dinor thromboxane B2 were much more important in sodium taurocholate- than in cerulein-induced acute pancreatitis. These data confirm an altered prostacyclin and thromboxane metabolism occurring in experimental acute pancreatitis. Phospholipase A2 activity and the effect of gabexate mesilate on the arachidonate metabolism were also evaluated.

Topics: 6-Ketoprostaglandin F1 alpha; Acute Disease; Amylases; Animals; Ceruletide; Epoprostenol; Gabexate; Lipase; Male; Pancreatitis; Phospholipases A; Phospholipases A2; Rats; Rats, Sprague-Dawley; Taurocholic Acid; Thromboxane A2; Thromboxane B2

Plasma thromboxane concentrations were found to be significantly elevated in acute necrotizing pancreatitis in rats, whereas prostaglandin I2 levels were not. The significance of these alterations was investigated. Pancreatitis was induced by injecting 5% sodium taurocholate into the pancreatic duct. Iloprost (ZK 36374, a stable analog of prostaglandin I2, 25 ng/kg body weight) decreased the mortality rate from 100% to 50%. When treatment with iloprost was combined with simultaneous administration of either Sibelium (flunarizine R 14,950, 0.2 mg/kg body weight) or dazmegrel (UK 38,485, 50 mg/kg body weight) an additional decrease in the mortality rate was recorded. Dazmegrel is a selective thromboxane A2 synthetase inhibitor and flunarizine (a calcium entry blocker) also inhibits the effects of elevated thromboxane A2 levels. With flunarizine and iloprost the mortality rate was 40% (P less than 0.05); with dazmegrel and iloprost it was 10% (P less than 0.01). The results of the present study suggest that thromboxane A2 and prostaglandin I2 play a role in the course of acute necrotizing pancreatitis.

Topics: Acute Disease; Animals; Epoprostenol; Flunarizine; Iloprost; Imidazoles; Male; Necrosis; Pancreas; Pancreatitis; Rats; Rats, Inbred Strains; Thromboxane A2; Vasodilator Agents

The possible role of thromboxane A2 (TXA2) in acute necrotizing pancreatitis (ANP) was investigated in rats. After ANP was induced by injecting sodium taurocholate (5% w/v) into the pancreatic duct, the thromboxane B2 (TXB2) levels in plasma increased significantly. The effects of indomethacin, a general blocker of prostaglandin synthesis, on survival time and on plasma TXB2 levels were compared with those of dazoxiben, a more specific blocker of TXA2 synthesis, and Flunarizine, a calcium entry blocker known to inhibit the effects of TXA2. In a test group without any treatment, all animals died within 30 h of ANP induction. Although TXB2 levels were lowered by the administration of indomethacin, dazoxiben, and Flunarizine, survival times were not significantly altered. Indomethacin pretreatment had no beneficial effect, whereas 30% and 40% of the animals survived for 36 h after treatment with Flunarizine and dazoxiben, respectively. The results of the present study indicate that inhibition of TXA2 synthesis alone does not dramatically alter survival time. However, a potential role for other arachidonate metabolites in ANP cannot be ruled out by this study.

Topics: Acute Disease; Animals; Flunarizine; Imidazoles; Indomethacin; Male; Necrosis; Pancreatitis; Rats; Rats, Inbred Strains; Thromboxane A2; Thromboxane B2