title: Dextran and carrageenan evoke different inflammatory responses in rat with respect to composition of infiltrates and effect of indomethacin.
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.
mesh_terms: D000818:Animals; D002351:Carrageenan / Q000494:pharmacology*; D003911:Dextrans / Q000494:pharmacology*; D005122:Exudates and Transudates / Q000166:cytology / Q000378:metabolism; D006636:Histamine Release / Q000187:drug effects; D007213:Indomethacin / Q000494:pharmacology*; D007249:Inflammation / Q000139:chemically induced* / Q000378:metabolism; D008297:Male; D008970:Molecular Weight; D011506:Proteins / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D003911:Dextrans; D011506:Proteins; D002351:Carrageenan; D007213:Indomethacin