1. Five new solvent systems are reported for the separation of 1-dimethylaminonaphthalene-5-sulphonylamino acids by thin-layer chromatography on silica gel. After two-dimensional chromatography with a suitable pair of these solvent systems, most of the 1-dimethylaminonaphthalene-5-sulphonyl derivatives were completely separated and could be located by their intense yellow fluorescence when viewed under u.v. light. 2. These techniques have been used to identify 21 amino acids present in superfusates of cat cerebral cortex, plasma and cerebrospinal fluid. 3. A method for the semiquantitative estimation of amino acids in biological fluids is described in which the fluorescent intensity of their separated 1-dimethylaminonaphthalene-5-sulphonyl derivatives was measured.

Homogenates of rat cerebral cortex contain material corresponding to prostaglandins E(1), E(2), F(1)alpha, and F(2)alpha which are concentrated mainly in the light microsomal and mitochondrial fractions. Only the former fraction exhibits significant ability to synthesize prostaglandins E(1) and F(1)alpha from bis-homo-gamma-linolenic acid. After subfractionation of the crude mitochondrial fraction, prostaglandin E and F material is found mainly in the cholinergic and noncholinergic nerve endings. We conclude that the nerve endings are a storage site, whereas the light microsomes are the site of synthesis.

Summary1. The prostaglandins are C20 unsaturated fatty acids which exhibit diverse physiological effects of short duration. We have invesitigated the speed of removal of PGE1 and PGFia from the circulating blood and their subsequent metabolism by the isolated perfused rat liver. 2. Following either a single injection of radiolabelled PGE1 or PGFia into the hepatic artery or portal vein, or recirculation of prostaglandins through the liver for 2-5 h, the distribution of radioactivity within extracts of bile, blood and liver was determined. The nature of the radioactive products of metabolism was inferred by comparison of the distribution of radioactivity after injecting carbon and tritium labelled standards, and by thin-layer chromatography, gas-liquid chromatography, ultraviolet and bioassay analysis.3. A single injection of 1-1"C PGE, indicated that the liver could efficiently remove 89-95% of circulating PGE1 on a single passage. Biliary excretion was excluded as a major route for elimination of unchanged PGE1, because only 0-3-0-8% of the injected radioactiviity was detected in the bile. During recirculation of 1-14C PGEI, 11-19% of the injected radioactivity was detected as exchanged "4CO2. The radioactivity detected within liver was identified with further fragments resulting from decarboxylation of PGEI, which were incorporated into fatty acids and then phospholipids.4. Studies with 5,6-3H PGE,, and comparison with the results obtained using 1-"C PGE1, revealed a 30-fold increase in the percentage of radioactivity excreted into the bile, suggesting that biliary excretion may be a major route for elimination of compounds smaller than C20 prostaglandin. Evidence that the cyclopentane ring was intact was inferred by formation of a PGB compound on treatment with alkali; similar biliary excretion of 9-3H PGFia also occurred. In addition, the increased radioactivity detected within the liver (37%) and blood (43 %) after a single injection of 5,6-3H PGE, had the solvent partition and thin-layer chromatography properties of PGE1, but were associated with a less polar compound smaller than the C20 parent structure.5. These results indicate rapid uptake of circulating prostaglandins by the rat liver. Decarboxylation of prostaglandins resul;ts in pharmacological inactivation. The products are excreted into the bile and venous effluent. These processes would curtail the duration of effects following prostaglandin injection.

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