Effect of inducible cyclooxygenase expression on local microvessel blood flow in acute interstitial pancreatitis.

ABSTRACT

OBJECTIVE: To investigate the role of inducible cyclooxygenase (COX-2) mRNA expression in local microvessels in rats with acute interstitial pancreatitis (AIP) induced by caerulein injection. METHODS: The reverse transcription polymerase chain reaction (RT-PCR) was used to detect COX-2 gene expression in pancreatic tissue. Parameters of acute pancreatitis, such as serum amylase (AMS) and plasma myeloperoxidase (MPO) activities, were assayed using spectrophotometry. Intravital fluorescence microscopy with fluorescein isothiocyanate-labelled erythrocytes was used to study the pancreatic microvessels of rats with AIP and normal control rats. RESULTS: Highly significant increases in COX-2 expression and AMS and MPO activity were seen in rats with AIP compared with controls. After caerulein injection, pancreatic capillary blood flow was decreased (4 hours, p > 0.05; 8 hours, p < 0.001), functional capillary density was reduced (4 hours, p > 0.05; 8 hours, p < 0.001), and there was irregular and intermittent capillary perfusion at 8 hours. There was also a positive correlation between the level of COX-2 expression and MPO activity (plasma, r = 0.5449, p < 0.05; tissue, r = 0.5698, p < 0.05). CONCLUSIONS: The correlations between increased COX-2 expression and decreased capillary perfusion and blood flow and increased oedema following AIP may show that COX-2 expression can induce neutrophil sequestration to the pancreas, which may be one of the cascading inflammatory factors in the development of AIP.