Does slow-reacting substance of anaphylaxis mediate hypoxic pulmonary vasoconstriction?

We have previously established a relationship between mast cell degranulation and hypoxic pulmonary vasoconstriction (HPV). In the present study, we investigated the possible role of slow-reacting substance off anaphylaxis (SRS-A) in the mediation off HPV. In 18 conscious sheep, pulmonary artery pressure, pulmonary arterial wedge pressure, and cardiac output were measured for the calculation of pulmonary vascular resistance (PVR) along with arterial oxygen tension (Pao2) while breathing room air and while breathing 13% 02 (balance, N2). Before and during 13% 02 breathing (pretreatment), Group 1 received an intravenous infusion off cromolyn sodium (3 mg/kg -1/min -1) and Group 2 was infused with FPL-57231, a SRS-A antagonist (2 mg/kg-1/min-1); Groups 3 and 4 received infusions off cromolyn sodium or FPL-57231 affter induction of HPV. During 13% 02 breathing (mean Pao2, 47 mmHg), mean PVR increased to 190% of baseline. Pretreatment with cromolyn sodium prevented HPV, whereas infusion of cromolyn sodium afft...