RESULTS

When tritium-labeled arachidonic acid was incubated with a homogenate of guinea pig lung, about 10% of the radioactivity was converted into products with chromatographic properties resembling prostaglandins. These products were not observed in a control experiment with boiled homogenate. A chromatogram of an extract from one of the incubations is shown in Fig. 1. The main peak (I) of radioactivity had an elution volume characteristic of PGF2,. Three small peaks (II, 111, and IV) appeared later in the chromatogram. Identijication of PGFta-The radioactive material present in the main peak (I in Fig. 1; 43 to 62 ml of effluent) was further analyzed by thin layer chromatography on AgNOs-impregnated silica gel with Solvent A III. Practically all of the radioactivity was found within the area of the reference sample of PGF2=. Treatment of part of the isolated material with diazomethane gave a radioactive product, which on a AgNOa-impregnated