Anaphylaxis in guinea-pig peripheral airways in vitro

The contributions made by histamine, prostaglandins (PG) and slow reacting substance (SRS-A) to anaphylactic contractions in isolated guinea-pig lung were investigated. Histamine, PGF2alpha and SRS-A induced isometric contractions in lung parenchymal strips and in tracheal smooth muscle. The effective concentrations of the autacoids were the same in lung strips and tracheas. Anaphylactic contractions in lung strips from bovine serum albumin sensitised animals were not affected by mepyramine (5 X 10(-6)M), or indomethacin (3 X 10(-5)M) but were markedly reduced by FPL 55712 (5 X 10(-5)M) suggesting that SRS-A plays a major role in the anaphylactic response. The effect of isoprenaline on anaphylactic histamine release and contractions was also examined. Anaphylactic contractions in lung strips were inhibited by isoprenaline (10(-10)--10(-7)M). Isoprenaline also inhibited anaphylactic histamine release from lung parenchyma. 10(-7)M isoprenaline inhibited contractions by 85.6% and reduced histamine release by 27.9%. The results suggest that histamine release does not contribute markedly to anaphylaxis in peripheral airways.