Release of rabbit aorta contracting substance (RCS) and prostaglandins induced by chemical or mechanical stimulation of guinea‐pig lungs

Abstract

1. Rabbit aorta contracting substance (RCS) and prostaglandins were released from guinea-pig isolated perfused lungs by gentle massage and also by infusion of Prosparol.2. RCS and prostaglandins were also released by infusion into the pulmonary artery of bradykinin, arachidonic and dihomo-gamma-linolenic acids or shock perfusate (containing RCS-releasing factor).3. Arachidonic and dihomo-gamma-linolenic acids caused a prolonged release of RCS and prostaglandins whereas bradykinin and shock perfusate gave a short-lasting output.4. RCS and prostaglandins, together with histamine were released when superfused chopped lung tissue was agitated.5. Challenge of sensitized guinea-pigs in vivo led to the release of an RCS-like substance into the carotid arterial blood.6. Intravenous injection of bradykinin into guinea-pigs also released an RCS-like substance.7. The release of RCS and prostaglandins was inhibited by aspirin or indomethacin in all experiments.8. RCS contracted all vascular tissues investigated and also rat stomach strip.9. The half-life of RCS was estimated as 1-2 minutes.