Actinomycin D Peritonitis in Rats

Abstract

The injection of 50 .mu.g i.p. of actinomycin D produces, in rats, a biphasic inflammatory reaction. The 1st short lasting phase (.apprx. 24 h) is characterized by the decrease of the peritoneal cells number, by the increase of the levels of both c[cyclic]AMP and cGMP in the peritoneal cells and by the increased synthesis and release of lysosomal enzymes from these cells. The 2nd long lasting phase (> 120 h) is characterized by the exudate formation, intense cellular immigration, continuous release of lysosomal enzymes, return to or below the normal values of the intracellular levels of cyclic nucleotides. The treatment of rats with a steroidal drug reduces the .beta.-glucuronidase release and, concomitantly, the intracellular cyclic nucleotide levels. Indomethacin is ineffective.