Multiple molecular forms of prostaglandin 15-hydroxydehydrogenase and 9-ketoreductase in chicken kidney

Prostaglandin-15-hydroxydehydrogenase and prostaglandin-9-ketoreductase were purified from chicken kidney. Both enzymes exist in multiple forms as determined by isoelectric focusing. The dehydrogenases catalyze the transformation of the functional group at C-15 but not the functional group at C-9. The preferred cofactors in these reactions are NAD⁺ or NADH. The 9-ketoreductases catalyze the reversible transformation of the functional group at C-9 and also the oxidation or reduction of the C-15 functional group. The preferred cofactors are NADP⁺ or NADPH. Bradykinin does not affect the activities of any of the three prostaglandin 9-ketoreductases. Flavin mononucleotide and the flavonoid, quercetin, as well as indomethacin, ethacrynic acid, and furosemide, inhibit all three 9-ketoreductases. An inhibitor of 9-ketoreductase isolated from chicken breast muscle also inhibits the three separable reductases, but the pattern of inhibition of the reductase that focuses at pH 5.7 differs from that of the reductases focusing at pH 7.8 and 8.2.     

Multiple molecular forms of prostaglandin 15-hydroxydehydrogenase and 9-ketoreductase in chicken kidney.

Prostaglandin-15-hydroxydehydrogenase and prostaglandin-9-keto-reductase were purified from chicken kidney. Both enzymes exist in multiple forms as determined by isoelectric focusing. The dehydrogenases catalyze the transformation of the functional group at C-15 but not the functional group at C-9. The preferred cofactors in these reactions are NAD+ or NADH. The 9-ketoreductases catalyze the reversible transformation of the functional group at C-9 and also the oxidation or reduction of the C-15 functional group. The preferred cofactors are NADP+ or NADPH. Bradykinin does not affect the activities of any of the three prostaglandin 9-ketoreductases. Flavin mononucleotide and the flavonoid, quercetin, as well as indomethacin, ethacrynic acid, and furosemide, inhibit all three 9-ketoreductases. An inhibitor of 9-ketoreductase isolated from chicken breast muscle also inhibits the three separable reductases, but the pattern of inhibition of the reductase that focuses at pH 5.7 differs from that of the reductases focusing at pH 7.8 and 8.2.     

Partial purification of prostaglandin E2-9-ketoreductase and prostaglandin-15-hydroxydehydrogenase from ovarian tissues of rabbits

Prostaglandin E2-9-ketoreductase (PGE2-9-KR) and prostaglandin-15-hydroxydehydrogenase (PG-15-HDH) have been purified 25.0- and 15.4-fold, respectively. The rate equations of the enzyme reaction for two substrates were used for the determination of kinetic constants. The Michaelis constant, Km, for PGE2 was 122 microM for the PGE2-9-KR and 8 microM for the PG-15-HDH. The presence of both enzymes in ovarian tissues of rabbits indicate that these tissues may be able to synthesize and metabolize PGF2 alpha.     

Studies on 15-hydroxyprostaglandin dehydrogenase with various prostaglandin analogues.

The NAD+-linked 15-hydroxyprostaglandin dehydrogenase (PGDH) of swine lung was purified to a high specific activity by affinity chromatographies on prostaglandin (PG)-and NAD+-Sepharose. The affinities of the enzyme for various synthetic analogues of PGA, E, F, and I and their inhibitory effects on the enzymatic reaction were examined. The modification of the alkyl side chain of PG, particularly at C-15 or C-16, reduced the affinity of the enzyme for these PG analogues. Furthermore, 14-methyl-13,14-dihydro-PGE1 and 16-cyclopentyl-omega-trinor-15-epi-PGE2 were potent inhibitors of PGDH.     

Evidence for several fold more activity of NAD+-dependent uterine prostaglandin 15-hydroxydehydrogenase in transsexual than in non-transsexual women

The activity of NAD+-dependent PGDH was measured in the cytosolic fractions (100,000 x g) of uterine tissues obtained from transsexual, pregnant and non-pregnant women. The specific activity (mean +/- SD) of the enzyme at maximum velocity of the enzyme reaction in these three groups of women was 5.5 +/- 2.30, 0.53 +/- 0.27 and 0.54 +/- 0.25 mU/mg protein respectively using PGE2 as substrate, and with PGF2 alpha as substrate the respective values were 5.48 +/- 2.80, 0.49 +/- 0.41 and 0.51 +/- 0.30 mU/mg protein. These data suggest that, with either substrate, the uterine enzyme activity in the transsexuals was about 10-fold greater than in pregnant and non-pregnant women (p less than 0.001). However, the Km values of the enzyme for both PGE2 and PGF2 alpha were similar in all three groups, indicating the presence of same enzyme in the uterus of transsexual, pregnant and non-pregnant women. We speculate that PGDH activity was raised in the uterus of transsexual women because of the prolonged androgen therapy they received for the management of female-to-male transsexualism.     

The action of 15-fluorine derivatives of prostaglandins E2 and F2 alpha on isolated smooth muscles

The effect of exchange of 15-hydroxyl for fluor on biological activity of PGF2 alpha and PGE2 on isolated smooth muscles of different organs has been studied. The exchange leads to significant increase in contractile (100-fold) and relaxation (1000-fold) activity of PGF2 alpha on smooth respiratory muscles. At the same time, the effect of 15-fluor-15-deoxyprostaglandin F2 alpha on smooth muscles of intestinal and vascular tracts did not differ from that of PGF2 alpha. Similar modification of PGE2 led to the decrease (10-fold) both in contractile and relaxation activity on all studied types of smooth muscles. The data obtained have been discussed within the boundaries of prostanoid receptor classification (Kennedy, 1982). Fluor derivative of PGF2 alpha may be used for pharmacological differentiation of EP-receptors.     

The synthesis of 15-methyl or 15,16-dimethyl prostaglandins

The synthesis of 15-methyl or 15,16-dimethyl prostaglandins has been accomplished starting from the lactone 1, the intermediate for the synthesis of natural prostaglandins.     

The action of various venoms on Escherichia coli

The antibacterial activity of honeybee venom (Apis mellifera), three snake venoms (Naja naja sputatrix, Vipera russellii and Crotalus adamanteus) and the polypeptide melittin was investigated against Escherichia coli. Minimum inhibitory concentration values, cell lysis and alterations in cell permeability were determined and action against E. coli was in the order: A. mellifera venom greater than melittin greater than N. naja sputatrix venom much greater than V. russellii venom greater than C. adamanteus venom. Cellular damage by A. mellifera and N. naja sputatrix venoms was evident in electron micrographs.     

The action of various venoms on Escherichia coli

The antibacterial activity of honeybee venom ( Apis mellifera ), three snake venoms ( Naja naja sputatrix, Vipera russellii and Crotalus adamanteus ) and the polypeptide melittin was investigated against Escherichia coli . Minimum inhibitory concentration values, cell lysis and alterations in cell permeability were determined and action against E. coli was in the order: A. mellifera venom > melittin > N. naja sputatrix venom ≫ V. russellii venom > C. adamanteus venom. Cellular damage by A. mellifera and N. naja sputatrix venoms was evident in electron micrographs.     

The mechanism of prostaglandin action on the pregnant human uterus

The concentrations of 15 methyl PGF2α, progesterone and estradiol in the peripheral plasma were assayed sequentially and the resting and active pressures of the uterus were quantitated in 10 first trimester pregnant patients, treated with a vaginal suppository containing 3 mg U-36,384. The purpose of the study was to determine the sequence of the prostaglandin induced changes in regulatory profile and uterine function and thus expose further the mechanism of prostaglandin action.The temporal relationships of the changes revealed that the primary action of exogenous prostaglandin is the disruption of the normal endocrine function of the conceptus and that the delayed oxytocic effect of this compound is secondary, a consequence of the primary action. Apparently prostaglandins are only effective as postconceptional agents if they convert the refractory normal pregnant uterus into a reactive organ. The academic and therapeutic significance of this finding is discussed.     

Luteolytic action of 15-keto prostaglandin F2alpha in the rhesus monkey.

The naturally-occurring metabolite of prostaglandin F2alpha, 15-keto prostaglandin F2alpha (15-keto PGF2alpha), elicited rapid and sustained declines in serum progesterone concentrations when administered to rhesus monkeys beginning on day 22 of normal menstrual cycles. Evidence for luteolysis of a more convincing nature was obtained in studies where a single dose of 15-keto PGF2alpha was given on day 20 of ovulatory menstrual cycles in which intramuscular injections of hCG were also given on days 18-20; serum progesterone concentrations fell precipitously in monkeys within 24 hours following intramuscular administration of 15-keto PGF2alpha. However, corpus luteum function was impaired in only 4 of 11 early pregnant monkeys when 15-keto PGF2alpha was administered on days 30 and 31 from the last menses, a time when the ovary is essential for the maintenance of pregnancy. Gestation failed in 2 additional monkeys 32 and 60 days after treatment with 15-keto PGF2alpha, but progressed in an apparently normal manner in the remaining 5 animals. Two pregnant monkeys treated with 15-keto PGF2alpha on day 42 from the last menstrual period, a time when the ovary is no longer required for gestation, continued their pregnancies uneventfully. Corpus luteum function was not impaired in 9 control monkeys which received injections of vehicle or hCG at appropriate times during the menstrual cycle or pregnancy.     

The effect of various acrylonitriles and related compounds on prostaglandin biosynthesis

We have studied the effect of nearly 90 arylacrylonitrile derivatives, and several related compounds, on the biosynthesis of prostaglandins from bovine seminal vesicle microsomes. This effect was compared to that of triarylacrylonitrile derivatives known for their inhibiting properties. Several arylacrylonitrile derivatives have also proved good inhibitors, especially certain N-trisubstituted compounds: trans (dimethylamino-4 phenyl)-3 (methoxy-4' phenyl)-2 acrylonitrile was the best inhibitor of the group, with an IC50 of 0.07 microM. The absence of carboxy groups in these derivatives precludes the application of any of the site-models proposed to date. We suggest that the electronic charges carried especially by the three aromatic rings play an important role in the inhibiting mechanism.     

The effect of various acrylonitriles and related compounds on prostaglandin biosynthesis

We have studied the effect of nearly 90 arylacrylonitrile derivatives, and several related compounds, on the biosynthesis of prostaglandins from bovine seminal vesicle microsomes. Thi effect was compared to that of triarylacrylonitrile derivatives known for their inhibiting properties. Several arylacrylonitrile derivatives have also proved good inhibitors, especially certain N-trisubstituted compounds : trans (dimethylamino-4 phenyl)-3 (methoxy-4′ phenyl)-2 acrylonitrile was the best inhibitor of the group, with an IC₅₀ of 0.07 μM.The absence of carboxy groups in these derivatives precludes the application of any of the site-models proposed to date. We suggest that the electronic charges carried especially by the three aromatic rings play an important role in the inhibiting mechanism.     

The effect of various prostaglandins and a prostaglandin synthetase inhibitor on rat anterior pituitary cyclic AMP levels and hormone release in vitro (38475).

(U)Prostaglandins E-1, E2,F-1alpha or F-2 alpha significantly increased the release of GH, with a parallel increase in intracellular cAMP concentrations, while they only protentiated HE-stimulated TSH release. (2) None of the prostaglandins examined consistently effected either the basal or HE-altered release of LH,FSH or prolactin. (3) The prostaglandin synthetase inhibitor, indomethacin, inhibited GH and TSH release and, at high doses of the drug, inhibited prolactin release. In contrast, the drug appeared to potentiate both He and sLRF-stimulated gonadotropin release. It had no significant effect on intracellular cAMP concentration.