Effects of bovine SRS-A (SRS-Abov) on bovine respiratory tract and lung vasculature in vitro.

Evidence from isolated bovine pulmonary vessels and respiratory smooth muscles suggests that bovine slow-reacting substance of anaphylaxis (SRS-Abov) may contribute to bronchoconstriction and pulmonary oedema during anaphylaxis in cattle. Bovine bronchus is sensitive to low concentrations of SRS-Abov and is considerably more sensitive than trachea. Contraction of the calf bronchus to SRS-Abov can be antagonized by sodium meclofenamate, suggesting prostaglandins may be involved in the contraction. Bovine pulmonary artery did not contract to SRS-A at any of the concentrations examined. None of the proposed SRS-A receptor antagonists, FPL 55712, PR-D-92-EA, or sodium meclofenamate, inhibit the effects of bovine SRS-A in bovine pulmonary vein.