A Comparison of Air Pouch, Sponge and Pleurisy Models of Acute Carrageenan Inflammation in the Rat

A comparative assessment of the time course of changes in three models of acute carrageenan-induced inflammation, the six-day air pouch, polyester sponge and pleurisy models, was obtained by measuring exudate volume, leucocyte numbers, PGE2 concentrations and lactate dehydrogenase activity at 2, 6 and 24 h. The greatest increases in exudate volume, leucocyte numbers and PGE2 concentration and the smallest rise in protein occurred in the air pouch model. Increases in lactate dehydrogenase were greatest in the sponge and least in the pleural exudate, indicating that the least cell damage occurred in the pleurisy model. PGE2 was not detectable in most pleural exudate samples. The actions of two steroids, betamethasone and dexamethasome, at two dose levels, 80 and 160 micrograms/kg, were assessed in each model. Overall, the six-day air pouch was found to be most satisfactory and most sensitive for assessing the actions of the steroids. The sponge model was either less sensitive or gave inconsistent responses, for the variables measured, than the cavity models of inflammation. Since the six-day air pouch has previously been shown to resemble synovium, our findings indicate that it is likely to be superior to the other two models as a model of joint inflammation.