Use of mini-columns packed with acid-washed Florisil for the rapid separation of A, E and F series prostaglandins.

A new procedure was developed for the rapid isolation of the A, E and F series prostaglandins from plasma extracts. This new procedure involves the use of mini-columns packed with acid-washed Florisil to rapidly separate the A, E and F series prostaglandins. These new mini-columns give flow rates of around 1 ml/min. and they generate a well-resolved chromatographic pattern while at the same time producing good recoveries for [3H]-labeled prostaglandins of the A, E and F series. Using these new mini-columns, large numbers of plasma extracts can be processed in a short period of time.     

Stimulation of bone resorption by various prostaglandins in organ culture

The ability of E,F,A and B prostaglandins to stimulate bone resorption was demonstrated in organ culture. All of the compounds tested were able to increase the release of previously incorporated ⁴⁵Ca from fetal rat bone by 60 to 135 per cent at maximally effective doses, but prostaglandins of the E series were 10- to 100- fold more potent than F,A or B prostaglandins. Compounds with two double bonds in the side chain were usually more potent than those with one double bond. PGE₂ stimulation of bone resorption increased linearly with the logarithm of the medium concentration over the range of 10⁻⁹M to 10⁻⁵M, then decreased at higher concentrations. PGE₂ stimulated bone resorption more slowly than did parathyroid hormone but caused complete resorption after six days in the culture system. Equilibrium dialysis studies showed no significant binding of F, and 16–34% binding of E and A prostaglandins to bovine serum albumin, which was present in the medium at 1 mg/ml. These differences in albumin binding could not account for differences in potency.     

Stimulation of bone resorption by various prostaglandins in organ culture

The ability of E,F,A and B prostaglandins to stimulate bone resorption was demonstrated in organ culture. All of the compounds tested were able to increase the release of previously incorporated ⁴⁵Ca from fetal rat bone by 60 to 135 per cent at maximally effective doses, but prostaglandins of the E series were 10- to 100- fold more potent than F,A or B prostaglandins. Compounds with two double bonds in the side chain were usually more potent than those with one double bond. PGE₂ stimulation of bone resorption increased linearly with the logarithm of the medium concentration over the range of 10⁻⁹M to 10⁻⁵M, then decreased at higher concentrations. PGE₂ stimulated bone resorption more slowly than did parathyroid hormone but caused complete resorption after six days in the culture system. Equilibrium dialysis studies showed no significant binding of F, and 16–34% binding of E and A prostaglandins to bovine serum albumin, which was present in the medium at 1 mg/ml. These differences in albumin binding could not account for differences in potency.     

Prostaglandins lack a direct inhibitory action on electrolyte and water transport in the kidney and the erythrocyte

The possibility of a direct effect of prostaglandins of the E, A, and F series upon renal electrolyte and water transport was assessed using in vitro preparations of rabbit cortical and medullary tubular suspensions as well as cortical renal slices from rat and guinea pig and medullary renal slices from rabbit. Net fluxes of Na, K, Cl and H₂O between the intracellular compartment and the extracellular fluid were measured in the presence of PGE₁, PGE₂, PGA₁, PGA₂ and PGF_2α in concentrations ranging from 1 × 10^?5 to 1 × 10^?10M. No inhibitory action was observed with any of these prostaglandins and in fact a slight stimulation of Na transport was seen under some circumstances. We conclude that the natriuresis which follows in vivo administration of some prostaglandins is not the result of a direct inhibition of Na reabsorption at the contraluminal pump site and is most likely secondary to renal vasodilation.We also studied net and isotopic Na fluxes in human erythrocytes. Na transport was not affected by prostaglandins of the E, A or F series using both normal and high sodium erythrocytes. Our results emphasize the need for caution in extrapolating the effects of prostaglandins upon Na transport from one tissue to another since their actions appear to be tissue-specific.     

Temporal effect of prostaglandins E and F on human adrenal cAMP and cortisol output.

The $\text{in vitro}$ modulating effects of the E and F series prostaglandins upon the cAMP and cortisol output of normal human adrenal dice were evaluated with time and compared to the effects of ACTH. PGE₁ and PGE₂ significantly increased human adrenal cAMP levels; cortisol output increased in a dose related manner. Although the cortisol levels produced by E prostaglandins and ACTH were quantitatively similar, on a molar basis ACTH was greater than 10⁶ fold more effective. PGE_1α, PGF_2α, PGF_1β and PGF_2β depressed adrenal cAMP, except PGF_2α and PGF_2β at 100 μg/ml. PGF_1α and PGF_2α depressed cortisol levels at all doses. Similarly, PGF_1β and PGF_2β also depressed cortisol output, except PGF_2β at 100 μg/ml which was stimulatory. In both series of prostaglandins the temporal responses were dose related in regard to the cyclic nucleotide and steroid alterations. The findings demonstrate the E and F series prostaglandins act antagonistically in respect to cAMP and cortisol output. In addition, as the cAMP level and cortisol output are not always correlated, it appears that these prostaglandin mediated events are separable. The relationship between adrenal prostaglandins and cyclic nucleotides, therefore, invites a more sophisticated second messenger concept in terms of adrenocortical function, than currently proposed.     

A simple isotope derivative assay for prostaglandins and prostaglandin metabolites. I. Assay of e-type prostaglandins.

Prostaglandins of the E series may be reduced with [³H]borohydride to their corresponding counterparts of the F series: during reduction a tritium label is incorporated into the molecule. We describe a simple assay based on this reaction which can be used to measure E-type prostaglandins, and with slight modifications, to measure F-, A-, and D-type prostaglandins, as well as the 15-keto and 13,14-dihydro-15-keto metabolites. The assay will estimate 1–10 ng PGE compounds (～10^?11–10^?12 moles) but some prior purification of the sample is necessary.     

Interaction of prostaglandins with blood plasma proteins. Comparative binding of prostaglandins A2, F2α and E2 to human plasma proteins

1. The binding of prostaglandin A(2) and prostaglandin F(2alpha) to human plasma proteins was investigated by DEAE-Sephadex chromatography and polyacrylamide-gel electrophoresis. Both prostaglandins, when added to human plasma in vitro, were found to become bound mainly to plasma albumin. 2. The extent of binding of prostaglandins added to human plasma in low to moderate concentrations was found to be approx. 88, 73 and 58% for prostaglandins A(2), E(2) and F(2alpha) respectively. The order of affinities for the binding of the three prostaglandins to albumin appear to be A(2)>E(2)>F(2alpha). 3. The apparent association constants for the binding of these prostaglandins to human serum albumin were estimated to be approx. 4.8x10(4), 2.4x10(4) and 0.9x10(4) litre/mol for prostaglandins A(2), E(2) and F(2alpha) respectively. The results are compared with previously reported association constants for the binding of long-chain fatty acids to both human and bovine albumins.     

Prostaglandins E3 and F3 alpha are excreted in human urine after ingestion of n - 3 polyunsaturated fatty acids

Prostaglandins E3 and F3 alpha, presumably of renal origin, were characterized for the first time in urine of volunteers after ingestion of n - 3 polyunsaturated fatty acids by combined gas chromatography-mass spectrometry. Quantitation of prostaglandins E3, E2, F3 alpha and F2 alpha using deuterated internal standards showed low levels of the 3 series prostaglandins in the control period. Levels of prostaglandins E3 and F3 alpha rose about 10-fold by the 12th week of the dietary trial and were still elevated 4-fold after a wash-out period of 20 weeks. Excretion of prostaglandins E2 and F2 alpha tended to be depressed in the 12th week of the dietary trial and rose again to control values after the wash-out period. Our data indicate that n - 3 polyunsaturated fatty acids are incorporated into the human kidney and are retained there for a long time. Prostaglandins E3 and F3 alpha may contribute to the observed favorable effects of marine oils rich in n - 3 polyunsaturated fatty acids on certain renal diseases.     

Basal level of human platelet prostaglandins: PGE1 is more elevated than PGE2.

Radioimmunoassays of platelet prostaglandins E1 and F1 alpha in platelet rich plasma or platelet suspension, demonstrate that both PGE1 and PGF1 alpha are present at higher concentrations than prostaglandins E2 and F2 alpha. Gas chromatography--mass spectrometry determinations of prostaglandins E1 and E2 in resting washed platelets confirm this difference. Lastly, there is a greater incorporation of [1--14C] acetate into prostaglandins E1 and F1 alpha compared to that into prostaglandins E2 and F2 alpha.     

Prostaglandins and inflammation: Enhancement of monocyte chemotactic responsiveness by prostaglandin E2

The effects of prostaglandins on human monocyte chemotaxis were studied $\text{in vitro}$. None of the prostaglandins tested, including members of the A, B, E or F series, were chemotactic for monocytes. Prostaglandin E₂ however, enhanced the chemotactic responsiveness of monocytes to complement - activated human serum by almost 200%. The enhancement of chemotaxis was not directly related to the ability of PGE₂ to raise intracellular cyclic AMP levels. These studies support a role for prostaglandins as modulators of the inflammatory response.     

Positive-negative, chemical-ionization, direct exposure mass spectrometry of underivatized prostaglandins

Nine underivatized prostaglandins were examined using direct exposure, ammonia, chemical-ionization, pulsed positive-negative ion mass spectrometry. The positive ion spectra were characterized by (M+18)⁺ ion adducts. The negative ion spectra were characterized by ions which dependence upon the functionality present in the cyclopentane ring system (acetal for TXB₂). The E and D series prostaglandins gave (M-18)⁻ as the major negative ion, while the F series and TXB₂ were characterized by negative ions corresponding to (M-1)⁻, and PGA₂ by the parent (M)⁻ ion. Prostaglandin 6-keto-PGF_1α was anomalous in this respect showing apparent dehydration, interpreted as an overall (M-18+1)⁺ and (M-18-1)⁻ in the positive and negative ion spectra, respectively. All major ion types were shown to give essentially a linear response with respect to concentration in the 10–1000 ng range. Although these initial studies were conducted under ideal conditions, it would appear that direct chemical ionization techniques show promise for providing direct structural information on prostaglandins without the need for prior chemical derivation.     

A simple, rapid selected ion monitoring method for the determination of prostaglandins E2 and F2 alpha in human urine

A new procedure for the simultaneous measurement of prostaglandins E2 and F2 alpha in human urine is described. Quantification was achieved by gas chromatography mass spectrometry with selected ion monitoring and deuterium labeled internal standards. The levels of measured prostaglandins ranged from 25 pg ml-1 of urine (PGE2) to 2500 pg ml-1 (PGF2 alhpa). The interassay coefficient of variation, determined by replicate analysis of four identical samples, was 1.9% for PGE2 and 0.8% for PGE2 alpha. The procedure takes a fraction of the time needed with published methods and can be conducted with as little as one-tenth of the daily urinary output.     

The effects of prostaglandins on the beating activity of cultured heart cells

The effects on the beating behavior of cultured rat heart cells of fourteen prostaglandins of the A, B, D, E, and F series were investigated, together with adrenaline and ouabain, at dose levels of 10⁻⁷ and 10⁻⁵M. Single heart cell beating activity was monitored photo-electrically and five parameters of beating behavior measured. Only PGF_2a markedly increased rate while PGF_2B reduced it. Maintenance of a stable rate (rate range) was minimally affected by prostaglandins with PGF_2β possibly reducing, and PGF_1α and 2-decarboxy E₁ possibly increasing, rate range. PGF_1α and F_2α both statistically reduced the percentage of cells beating while the other prostaglandins had no effect. Most of the prostaglandins either produced no change, or reduced, indices of contractile force (optical density changes with contractions and its first derivative (dOD/dt)). Only the negative chronotropic agent PGF_2β positive density effect. In conclusion, except for PGF_2α, prostaglandins generally have limited actions on the beating activity of cultured heart cells.     

Prostaglandins and inflammation: enhancement of monocyte chemotactic responsiveness by prostaglandin E2.

The effects of prostaglandins on human monocyte chemotaxis were studied in vitro. None of the prostaglandins tested, including members of the A, B, E or F series, were chemotactic for monocytes. Prostaglandin E2 however, enhanced the chemotactic responsiveness of monocytes to complement - activated human serum by almost 200%. The enhancement of chemotaxis was not directly related to the ability of PGE2 to raise intracellular cyclic AMP levels. These studies support a role for prostaglandins as modulators of the inflammatory response.     

Synthesis and release of prostaglandins by rat brain synaptosomal fractions.

Abstract— Particulate fractions from rat brain homogenate containing the synaptosomes synthesize and release prostaglandins F and E on aerobic incubation. The prostaglandin of the F-typc released could be further identified as proslaglandin F_2α using specific radioimmunoassays for prostaglandins F_1α, and F_2α-. The metabolite 13,14-dihydro-15-keto-prostaglandin F_2α could not be detected. The amount of prostaglandins released is dependent on incubation time and temperature as well as pH and osmolarity of the incubation medium. Total brain homogenate released more prostaglandins than purified synaptosomes per mg protein, indicating that synaptosomes are probably not a main source of prostaglandins when compared with other subcellular brain fractions. While prostaglandin synthesis was only moderately increased by the addition of the precursor fatty acid arachidonic acid, anti-inflammatory drugs like indomethacin, high concentrations of some local anaesthetics and Δ¹-tetrahydrocannabinol inhibited prostaglandin release. The neurotransmitters noradrenaline, dopamine and 5-hydroxytryptamine did not influence prostaglandin release from the synaptosomal rat brain fractions.     

Hydrocortisone inhibition of the bradykinin activation of human synovial fibroblasts

Human synovial fibroblasts in culture respond to bradykinin with a 20-fold increment in intracellular cyclic AMP concentrations, however bradykinin does not directly activate adenylate cyclase activity in a particulate fraction derived from these cells. Bradykinin evokes a release of labeled arachidonic acid and prostaglandins E and F from synovial fibroblasts pre-labeled with ³H-arachidonic acid. Hydrocortisone inhibits the bradykinin induced increment in cyclic AMP and the release of arachidonic acid and prostaglandins E and F from synovial fibroblasts. Indomethacin, which also inhibits the cyclic AMP response to bradykinin, has no effect on the release of arachidonic acid from synovial fibroblasts. Indomethacin does, however, inhibit the quantity of prostaglandins released into the medium. These studies support the hypothesis that bradykinin does not activate human synovial fibroblast adenylate cyclase, but presumably activates a phospholipase whose products in turn result in the synthesis of prostaglandins. These and other investigations also suggest that a product(s) of the prostaglandin pathway causes the increment in cyclic AMP.     

Radioimmunoassay of PGE and an approach to the specific measurement of PGE1

A specific radioimmunoassay for prostaglandins of the E series is presented. Several refinements of the conventional procedures used for unknown sample preparation prior to assay are described. Validation of the method through recovery of labeled and unlabeled prostaglandin E from plasma indicates: 74% extraction efficiency, 80% chromatographic separation efficiency, and a 67% overall recovery figure for the complete assay. The development of an “absorbed system” approach for measuring one E prostaglandin (PGE₁) without interference from the other E prostaglandin (PGE₂) is also described. A preliminary study of rat tissue and male plasma samples measured by these assay systems is included. Alternate approaches to the development of a specific PGE₁ assay, although less feasible in these authors' hands, are discussed.     

Uterine vein prostaglandin levels in late pregnant dogs.

We studied the uterine venous plasma concentrations of prostaglandins E2, F2 alpha, 15 keto 13,14 dihydro E2 and 15 keto 13,14 dihydro F2 alpha in late pregnant dogs in order to evaluate the rates of production and metabolism of prostaglandin E2 and F2 alpha in pregnancy in vivo. We used a very specific and sensitive gas chromatography-mass spectrometry assay to measure these prostaglandins. The uterine venous concentrations of prostaglandin E2 and 15 keto 13,14 dihydro E2 were 1.35 +/- .27 ng/ml and 1.89 +/- .37 ng/ml, respectively; however, we could not find any prostaglandin F2 alpha and very little of its plasma metabolite in uterine venous plasma. Since uterine microsomes can generate prostaglandin F2 alpha and E2 from endoperoxides, prostaglandin F2 alpha production in vivo must be regulated through an enzymatic step after endoperoxide formation. Prostaglandin E2 is produced by pregnant canine uterus in quantities high enough to have a biological effect in late pregnancy; however, prostaglandin F2 alpha does not appear to play a role at this stage of pregnancy.     

19F Nuclear Magnetic Resonance as a Tool To Investigate Microbial Degradation of Fluorophenols to Fluorocatechols and Fluoromuconates

A method was developed to study the biodegradation and oxidative biodehalogenation of fluorinated phenols by ¹⁹F nuclear magnetic resonance (NMR). Characterization of the ¹⁹F NMR spectra of metabolite profiles of a series of fluorophenols, converted by purified phenol hydroxylase, catechol 1,2-dioxygenase, and/or by the yeast-like fungus Exophiala jeanselmei, provided possibilities for identification of the ¹⁹F NMR chemical shift values of fluorinated catechol and muconate metabolites. As an example, the ¹⁹F NMR method thus defined was used to characterize the time-dependent metabolite profiles of various halophenols in either cell extracts or in incubations with whole cells of E. jeanselmei. The results obtained for these two systems are similar, except for the level of muconates observed. Altogether, the results of the present study describe a ¹⁹F NMR method which provides an efficient tool for elucidating the metabolic pathways for conversion of fluorine-containing phenols by microorganisms, with special emphasis on possibilities for biodehalogenation and detection of the type of fluorocatechols and fluoromuconates involved. In addition, the method provides possibilities for studying metabolic pathways in vivo in whole cells.     

Stimulation of bone resorption by various prostaglandins in organ culture.

The ability of E, F, A and B prostaglandins to stimulate bone resorption was demonstrated in organ culture. All of the compounds tested were able to increase the release of previously incorporated 45Ca from fetal rat bone by 60 to 135 per cent at maximally effective doses, but prostaglandins of the E series were 10- to 100- fold more potent than F, A or B prostaglandins. Compounds with two double bonds in the side chain were usually more potent than those with one double bond. PGE2 stimulation of bone resorption increased linearly with the logarithm of the medium concentration over the range of 10(-9)M to 10(-5)M, then decreased at higher concentrations. PGE2 stimulated bone resorption more slowly than did parathyroid hormone but caused complete resorption after six days in the culture system. Equilibrium dialysis studies showed no significant binding of F, and 16-34% binding of E and A prostaglandins to bovine serum albumin, which was present in the medium at 1 mg/ml. These differences in albumin binding could not account for differences in potency.