THE 6-DAY-OLD RAT AIR POUCH MODEL OF INFLAMMATION - CHARACTERIZATION OF THE INFLAMMATORY RESPONSE TO CARRAGEENAN

Inflammation was induced in the 6-day-old rat air pouch by injection o f carrageenan. The model was characterized in terms of exudate volume, leucocyte influx, cell free protein, prostaglandin E(2) levels, and g ranuloma formation. The time course of all these inflammatory markers, except prostaglandin E(2),, showed a 3-hr lag followed by a rapid inc rease to 8 hr. Thereafter, the rate of increase was much slower to 48 hr. Differential cell counts indicated a predominantly polymorphonucle ar cell response (75%) during the first 48 hr. Prostaglandin E, levels increased rapidly after a 3-hr lag, to a maximum of 440 +/- 140 ng/mL at 15 hr and thereafter quickly declined to 140 +/- 60 ng/mL at 21 hr . Prostaglandin E(2) levels were the most sensitive inflammatory marke r to (S+)-ibuprofen and were reduced dose dependently in the range 0.0 5 to 1 mg/kg. We have demonstrated the time course for duration of NSA ID-induced reduction of prostaglandin E(2) levels during inflammation in an individual animal. Rac-ibuprofen (0.1-1 mg/kg) reduced leucocyte influx at 3 and 5 hr, after which drug effects gradually diminished b y 24 hr. Rac-ibuprofen at 1 mg/kg significantly reduced the volume of air pouch exudate recovered at 24 hr but had no effect on protein leve ls.