Release of mediators of anaphylaxis: inhibition of prostaglandin synthesis and the modification of release of slow reacting substance of anaphylaxis and histamine.

1 When isolated perfused lungs from sensitized guinea-pigs were challenged with antigen, histamine, slow reacting substance of anaphylaxis (SRS-A) and prostaglandin-like substances were released into the effluent. 2 Treatment of the lungs before and during challenge with indomethacin (0.5--10 microgram/ml), sodium aspirin (1--10 microgram/ml), sodium meclofenamate (0.1--1 microgram/ml) or ketoprofen (0.5--5 microgram/ml) inhibited the release of prostaglandins while increasing the output of histamine and SRS-A between three- and five-fold. 3 Diethylcarbamazine (0.2--1 mg/ml) reduced the release of SRS-A and histamine but increased the amount of prostaglandin-like substances produced. 4 Eicosatetraynoic acid (10 microgram/ml) inhibited formation of prostaglandins but did not modify release of histamine and SRS-A. 5 The results with non-steroid anti-inflammatory drugs and diethylcarbamazine suggest that prostaglandins, or some other product of the cyclo-oxygenase system, depress the anaphylactic release of SRS-A and histamine.