16-16-dimethylprostaglandin-e2 and Edema

Oxygen free radicals and prostaglandins are implicated in the pathophysiology of acute pancreatitis, although their mechanisms of action remain unclear. We have studied the effect of administration of exogenous 16,16-dimethyl prostaglandin E2 and superoxide dismutase on oxygen free radical production in acute pancreatitis. For this purpose, five experimental rat groups were studied: group I, control; group II, sodium taurocholate-induced acute pancreatitis; group III, same as group II but with previous administration of 16,16-dimethyl prostaglandin E2; group IV, same as group II but with previous administration of indomethacin; and group V, same as group II but with previous administration of superoxide dismutase. In sodium taurocholate-treated rats, xanthine dehydrogenase is completely converted to xanthine oxidase within the first 5 min with subsequent oxygen free radical production while in 16,16-dimethyl prostaglandin E2-treated rats this enzyme transformation does not occur. In the superoxide dismutase-treated group xanthine oxidase activation is partially prevented. These data suggest that xanthine oxidase is the main source of oxygen free radicals, which contribute to extending the cellular damage in sodium taurocholate-induced acute pancreatitis.

Topics: 16,16-Dimethylprostaglandin E2; Acute Disease; Animals; Edema; Enzyme Activation; Free Radicals; Indomethacin; Lipase; Lipid Peroxidation; Male; Pancreatitis; Rats; Rats, Wistar; Reactive Oxygen Species; Superoxide Dismutase; Taurocholic Acid; Xanthine Dehydrogenase; Xanthine Oxidase

We studied the conversion of acute edematous pancreatitis (AEP) to acute hemorrhagic pancreatitis (AHP) in an experimental model in cats. In the model, 16,16 dimethyl PgE2 effects this conversion by increasing microvascular permeability. First, we induced AEP in cats and then gave PgE2 at increasing intervals after the induction of AEP to see how long an interval would still allow conversion. In 6 groups of cats, PgE2 was administered for 2 h, starting at 2, 4, 6, 8, 10, or 12 h after the creation of AEP. Twelve h later, the cats were sacrificed and the pancreases were graded for inflammation and hemorrhage. Significant pancreatic hemorrhage did not occur when the PgE2 was administered at 12 h compared to 2 h. Next, we determined that PgE2 still retained its ability to increase pancreatic vascular permeability when administered 12 h after the creation of AEP. This was done by perfusing a marker molecule through the MPD (fluorescein isothiocyanate labeled dextran: FITC-D, mol wt 20,000) and then finding it in portal venous blood (PVB). The presence of FITC-D in PVB signified increased vascular permeability, since normally none was present. We concluded that conversion of AEP to AHP was possible during the first 12 h after induction of AEP. Lack of conversion at 12 h was not caused by a lack of vascular reactivity at that time.

Topics: 16,16-Dimethylprostaglandin E2; Acute Disease; Animals; Capillary Permeability; Cats; Disease Models, Animal; Edema; Gastrointestinal Hemorrhage; Pancreatic Juice; Pancreatitis; Time Factors