Abstract
A study of the anti-inflammatory reaction after the injection of dextrans (60 mg) of various molecular weights (10,000-2,000,000) or carrageenan (0.5 mg) into the rat pleural cavity revealed two types of response. The dextrans induced within 30 min partial degranulation of mast cells and a rapid accumulation of fluid with little protein and a few neutrophils. This response was not suppressed by treatment with indomethacin. Carrageenan, in contrast, caused no mast cell degranulation, histamine release or early edema, but a progressive accumulation of a protein-rich exudate which contained large numbers of neutrophils. This response was inhibited by indomethacin. A commercial variety of dextran (mw 250,000) produced both types of response in which a rapid infiltration of protein-free fluid into the pleural cavity was followed by the appearance of protein and numerous neutrophils. The major plasma proteins were identified in exudates collected 4 hr after the injection of either carrageenan and the commercial dextran; in both cases, the numbers of neutrophils were related to the protein content of the exudate. The data suggest that inflammatory infiltrates may be formed through two distinct mechanisms: one associated with transudation of protein-free fluids, the other to exudation of plasma proteins and neutrophils. There are indications that these responses may involve different mediators.
JPET articles become freely available 12 months after publication, and remain freely available for 5 years.Non-open access articles that fall outside this five year window are available only to institutional subscribers and current ASPET members, or through the article purchase feature at the bottom of the page.
|