Fig. 6. Concentration of 6-keto prostaglandin F1α(6-keto PGF1α), a stable metabolite of prostacyclin, released by endothelium-denuded pulmonary arterial rings. Production of 6-keto PGF1αis expressed as picogram per milligram wet weight per 12 min (n = 7). Phenylephrine (PE; 10−5m) increased (* P < 0.01) the production of 6-keto PGF1αby sixfold in control rings. Pretreatment with propofol (10−4m) or ibuprofen (10−5m) abolished (#P < 0.01) the phenylephrine-induced increase in 6-keto PGF1α.