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The effects of prostaglandins on adenylate cyclase activity have been examined in membranes purified from normal rat liver and from a series of Morris hepatomas. Prostaglandin E1 gave the greatest stimulation (up to two-fold) in all membranes. However, prostaglandins A1, A2, and F2alpha, although stimulatory in liver and four tumor membranes, were inhibitory of adenylate cyclase activity in membranes from two of the fast-growing tumors. Arrhenius plots yielded broken line curves (at 20 degrees C) for the basal activity of all enzymes. Addition of various prostaglandins caused shifts in the broken line curves and/or produced nonbroken (straight) line curves for the liver and many of the hepatoma adenylate cyclases.

Adenylate cyclase (EC 4.6.1.1) activities were examined in membrane preparations from two rat liver cell lines (62 and 3C4) which were grown in monolayer cultures. The cells were epithelial-like in growth character. Adenylate cyclase from the line 62 was stimulated by epinephrine, Gpp(NH)p, and prostaglandins A1,A2,E1,E2, and F2alpha, but not by glucagon. Arrhenius plots of adenylate cylase activity from line 62 gave straight lines, except when epinephrine was present in the assay; epinephrine-stimulated activity gave a distinct break at 20 degrees C. Adenylate cyclase activity in line 3C4 was stimulated by glucagon ten times greater than by epinephrine. It was responsive to Gpp(NH)p and all the prostaglandins. Arrhenius plots of adenylate cyclase activity of line 3C4 always gave straight line curves. Prostaglandins flattened the straight line curves (allowed temperature independence) of adenylate cyclase activity in membranes from both cell lines.

8-Methoxypsoralen (8-MOP) levels in the blood of vitiligo patients were determined through the use of a reverse-phase high-performance liquid chromatographic method. The overall recovery of the internal standards was 85-94%, with the lower detection limit of 8-MOP at 2 ng. Peak blood levels as low as 130 ng/ml and as high as 3892 ng/ml were obtained in patients at 1-3 h following the oral administration of 0.6 mg/kg body weight of Oxsoralen capsules (Elder Pharmaceuticals Co.). These results are consistent with the clinical observation that maximum response in phototherapy is obtained at about 2 h after oral administration of the drug. Two hours after oral administration of 0.6 mg/kg of Oxsoralen, 8-MOP levels in the epidermis, dermis, and whole skin of the guinea pig (in ng/g) were: epidermis, 330 +/- 20; dermis, 89 +/- 16; whole skin, 379 +/- 19. Also detected were 8-MOP levels of 441 +/- 22 ng/ml in aqueous humor, 166 +/- 18 ng/ml in vitreous gel, 355 +/- 15 ng/g in lens, and 410 +/- 26 ng/g in retina. These results point to the fact that the eyes of the patient must be protected from exposure to sunlight after psoralen UV treatment, and that 8-MOP is absorbed in blood unevenly and varies from patient to patient. The fact that only 50-60% of the patients responded to psoralen photochemotherapy for vitiligo may be related to the variation of absorption of the drug in individual patients.

The binding of adenine nucleotides to liver adenylate kinase was dependent on Mg2+ ions. Citric acid enhanced the binding of all metal-chelated radioactive nucleotides and indicated two observable binding sites for Mg3H-ADP and Mg3-ATP and one-half binding site for Mg3H-AMP. Two binding sites of Mg3H-ADP and one binding site for Mg3H-ATP were also observed in the absence of citric acid. Stoichiometric binding of 14C-citric acid to liver adenylate kinase varied with additions of different nucleotides. AMP prevented whereas ADP and ATP enhanced the binding of 14C-citric acid.

The major enzymatic forms of adenylate kinase have been purified to homogeneity from fetal liver and adult brain of the rat. The two enzymes differ with respect to isoelectric points, Km (ATP), Km (AMP), and Ka (citrate). Antibody to adult liver adenylate kinase does not inhibit either enzyme, while entibody to adult skeletal muscle enzyme inhibits the brain enzyme but not the fetal liver enzyme. It is therefore probable that there are three major forms of adenylate kinases in fetal and adult rat tissues.