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

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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-γ-linolenic acids or shock perfusate (containing RCS-releasing factor). 3 Arachidonic and dihomo-γ-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 super-fused 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.