Release of prostaglandins from intact fetal lamb ductus arteriosus

1983 ◽  
Vol 61 (5) ◽  
pp. 240-247 ◽  
Author(s):  
C. R. Pace-Asciak ◽  
G. Rangaraj
Keyword(s):  
Gas Chromatography ◽  
Arachidonic Acid ◽  
Ductus Arteriosus ◽  
Significant Proportion ◽  
Calcium Ionophore ◽  
Major Product ◽  
Electron Capture Detection ◽  
Prostaglandin E ◽  
Physiological Importance ◽  
Near Term

Intact rings and slices of ductus arteriosus from fetal lambs near term (130–143 days gestation) were incubated with [14C]arachidonic acid and the fate of the label in the incubation fluid and tissue was followed by thin-layer radiochromatography (TLC). Prostaglandins formed from endogenous stores of arachidonic acid were assayed by capillary gas chromatography with electron-capture detection. In additional experiments, the prelabelled tissue was incubated with various drugs (e.g., angiotensin II, bradykinin, and calcium ionophore) to determine their effects on the release of 14C-labelled prostaglandins. Results indicate that the ductus arteriosus is oriented towards forming prostaglandin (PG) I2, with PGE2 being formed to a minor extent in all studies. While radiochromatographic studies (TLC) suggested a considerable complexity mostly because of overlapping products (PGs and metabolites), this was resolved using gas chromatography where a complete resolution of PGs from these metabolites was observed. In the tissue-labelling experiments most of the radioactivity remained in the incubation fluid and was recovered as unchanged arachidonic acid, although a small but significant proportion of label was observed in a mixture of prostaglandins (4.2 ± 0.6%, n = 16) with 6-keto PGF1α being the major product. The ductus tissue incorporated a small amount of label (3.4 ± 0.4%, n = 19) of which 49.7 ± 4.9% (n = 13) was found in the tissue phospholipids. Hydrolysis of tissue-bound [14C]arachidonic acid, which appeared in the perfusing medium together with 14C-labelled prostaglandins, was in the range of 28.0 ± 2.7% (n = 9) of total tissue radioactivity per experiment. Although 42.2 ± 2.5% (n = 18) of the radioactivity released by each of the drugs represented a mixture of prostaglandins and their metabolites (the rest recovered as arachidonic acid), no appreciable selectivity by any of the drugs was found for either the stimulation of phospholipase activity in this tissue or for the rerouting of the prostaglandin synthetic system to form prostaglandin E2 instead of I2. We conclude that prostaglandin I2 rather than E2 is probably of physiological importance in this unique fetal blood vessel.

Involvement of intramural prostaglandin E2 in prenatal patency of the lamb ductus arteriosus

1986 ◽  
Vol 64 (6) ◽  
pp. 737-744 ◽  
Author(s):  
Flavio Coceani ◽  
Dayle Huhtanen ◽  
Nancy C. Hamilton ◽  
Isis Bishai ◽  
Peter M. Olley
Keyword(s):  
Release Rate ◽  
Enzyme System ◽  
Reduced Glutathione ◽  
Ductus Arteriosus ◽  
Prostaglandin E ◽  
Concomitant Treatment ◽  
Contractile State ◽  
Wet Weight ◽  
Near Term

Release of prostaglandin E2 (PGE2) was studied in isolated ductus arteriosus preparations from immature (103 or 104 days gestation; term, 147 days) and near-term fetal lambs. Mature preparations produced measurable amounts of the compound in most cases and the release rate was 19 ± 2 pg/(100 mg wet weight∙min) at a [Formula: see text] of 3–8 Torr (1 Torr = 133.3 Pa). PGE2 release increased with the [Formula: see text] of the medium, peak values (about 125 pg/(100 mg∙min)) being attained at 106–276 Torr when the oxygen-induced contraction was still submaximal. Experiments in which tissues were either contracted with excess potassium or relaxed with CO proved that PGE2 formation is independent from the contractile state. PGE2 was also released from ductus preparations lacking the adventitia, the intima, or both; however, release values were maximal when the adventitia was preserved. The magnitude of the intrinsic tone in these stripped preparations was inversely related to the rate of PGE2 formation. Reduced glutathione increased PGE2 release from the mature ductus, whole or stripped, and also relaxed hypoxic preparations; both effects were reversed by concomitant treatment with indomethacin. PGE2 synthesis tended to be greater in the immature than the mature ductus, maximal values (115 ± 27 pg/(100 mg∙min)) being observed at 6–8 Torr. We conclude that the ductus arteriosus is endowed with an enzyme system for the synthesis of PGE2 whose function accords with an effector role of the compound in the regulation of tone. These findings, together with the potent relaxation exerted by PGE2 at low [Formula: see text], indicate that the locally generated prostaglandin is well suited for keeping the ductus patent in the fetus.

Evidence against a role for lipoxygenase-derived products of arachidonic acid in the lamb ductus arteriosus

1982 ◽  
Vol 60 (3) ◽  
pp. 345-349 ◽  
Author(s):  
F. Coceani ◽  
V. M. Jhamandas ◽  
E. Bodach ◽  
J. Labuc ◽  
P. M. Olley ◽  
...  
Keyword(s):  
Arachidonic Acid ◽  
Oxygen Tension ◽  
Ductus Arteriosus ◽  
Prostaglandin E ◽  
Cyclooxygenase Inhibitor ◽  
Hypoxic Conditions ◽  
Leukotriene Antagonist

The effects of leukotrienes, the leukotriene antagonist FPL55712 (sodium 7-(3-(4-acetyl-3-hydroxy-2-propyl-phenoxy)-2-hydroxypropoxy)-4-oxo-8-propyl-4H-1-benzopyran-2-carboxylate), and inhibitors of arachidonate lipoxygenase and cyclooxygenase (compound BW755C, 3-amino-1-(m-(trifluoromethyl)-phenyl)-2-pyrazoline; ETYA, 5,8,11,14-eicosatetraynoic acid) were studied in an isolated preparation of ductus arteriosus from mature foetal lambs. Leukotrienes (LT) C4 and D4 produced a modest relaxation of the ductus but only at the highest concentrations tested (10−7 to 10−6 M) and under hypoxic conditions ([Formula: see text], 6–9 Torr (1 Torr = 133.322 Pa)). LTB4 had no effect at any concentration tested. BW755C (10−6 to 10−5 M) and FPL55712 (10−5 M) contracted the hypoxic ductus; however, their action was abolished by pretreatment of the tissue with the cyclooxygenase inhibitor indomethacin (2.8 × 10−6 M). Indomethacin-treated preparations were also unresponsive to ETYA 3 × 10−5 M. The contraction of hypoxic tissues to either BW755C or FPL55712 increased further upon raising the oxygen tension of the medium ([Formula: see text] 591–691 Torr). These findings indicate that leukotrienes and allied compounds formed from lipoxygenase-catalysed reactions do not contribute to prenatal patency of the ductus and are unlikely to have a role in its closure at birth. It is also confirmed that prostaglandin E2 is essential for keeping the vessel patent in the foetus.

Occurrence of endothelium-derived relaxing factor – nitric oxide in the lamb ductus arteriosus

1994 ◽  
Vol 72 (1) ◽  
pp. 82-88 ◽  
Author(s):  
Flavio Coceani ◽  
Lois Kelsey ◽  
Eric Seidlitz
Keyword(s):  
Nitric Oxide ◽  
Methylene Blue ◽  
Ductus Arteriosus ◽  
Nonsteroidal Antiinflammatory Drugs ◽  
Prostaglandin E ◽  
Antiinflammatory Drugs ◽  
Relaxing Factor ◽  
Endothelium Derived Relaxing Factor ◽  
Near Term ◽  
Nitric Oxide Inhibitors

To determine whether the ductus arteriosus can form endothelium-derived relaxing factor – nitric oxide, we used isolated ductal strips from near-term fetal lamb and examined their response to bradykinin (a nitric oxide stimulator), L-arginine (a nitric oxide precursor), and agents interfering with the synthesis (Nω-nitro-L-arginine) and action (methylene blue) of nitric oxide. Bradykinin relaxed the indomethacin-contracted ductus dose dependently from a threshold of about 10−10 M, and peak relaxation was greater at high (176–210 mmHg; 1 mmHg = 133.3 Pa) than low (15–25 mmHg) [Formula: see text]. Bradykinin relaxation was nearly completely or completely abolished in endothelium-denuded preparations and, in its place, there was often a small contraction. Pretreatment with nitric oxide inhibitors also prevented, in part (methylene blue, 1 μM) or in full (Nω-nitro-L-arginine, 100 μM), the relaxant effect of bradykinin. Paradoxically, L-arginine (10 μM) had an inhibiting rather than an enhancing effect on the bradykinin relaxation. Nω-Nitro-L-arginine (100 μM) and methylene blue (1–100 μM) contracted by themselves the untreated ductus, and their action persisted after removal of the endothelium. These findings indicate the presence in the ductus arteriosus of a nitric oxide based relaxing mechanism, which may supplement prostaglandin E2 in keeping the vessel patent in the fetus. This mechanism may, on one hand, afford protection against nonsteroidal antiinflammatory drugs in utero and may, on the other hand, complicate the management of prematures with persistent ductus and account for failures of the indomethacin therapy.Key words: ductus arteriosus patency and closure, endothelium-derived relaxing factor – nitric oxide, prostaglandin.

Airway synthesis of 20-hydroxyeicosatetraenoic acid: metabolism by cyclooxygenase to a bronchodilator

1999 ◽  
Vol 276 (2) ◽  
pp. L280-L288 ◽  
Author(s):  
Elizabeth R. Jacobs ◽  
Richard M. Effros ◽  
John R. Falck ◽  
K. Malla Reddy ◽  
William B. Campbell ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography ◽  
Arachidonic Acid ◽  
Airway Resistance ◽  
Acid Metabolism ◽  
Gas Chromatography Mass Spectrometry ◽  
Dependent Manner ◽  
Hydroxyeicosatetraenoic Acid ◽  
Polar Metabolites ◽  
H 20

Rabbit airway tissue is a particularly rich source of cytochrome P-4504A protein, but very little information regarding the effect(s) of 20-hydroxyeicosatetraenoic acid (20-HETE) on bronchial tone is available. Our studies examined the response of rabbit bronchial rings to 20-HETE and the metabolism of arachidonic acid and 20-HETE from airway microsomes. 20-HETE (10−8 to 10−6 M) produced a concentration-dependent relaxation of bronchial rings precontracted with KCl or histamine but not with carbachol. Relaxation to 20-HETE was blocked by indomethacin or epithelium removal, consistent with the conversion of 20-HETE to a bronchial relaxant by epithelial cyclooxygenase. A cyclooxygenase product of 20-HETE also elicited relaxation of bronchial rings. [14C]arachidonic acid was converted by airway microsomes to products that comigrated with authentic 20-HETE (confirmed by gas chromatography-mass spectrometry as 19- and 20-HETE) and to unidentified polar metabolites. [3H]20-HETE was metabolized to indomethacin-inhibitable products. These data suggest that 20-HETE is an endogenous product of rabbit airway tissue and may modulate airway resistance in a cyclooxygenase-dependent manner.

Residue Analysis of Organophosphorus and Organochlorine Pesticides in Fatty Matrices by Gas Chromatography Coupled with Electron-Capture Detection

2006 ◽  
Vol 61 (5-6) ◽  
pp. 341-346 ◽  
Author(s):  
Jae-Woo Park ◽  
A. M. Abd El-Aty ◽  
Myoung-Heon Lee ◽  
Sung-Ok Song ◽  
Jae-Han Shim
Keyword(s):  
Gas Chromatography ◽  
Electron Capture ◽  
Simple Procedure ◽  
Linear Regression Analysis ◽  
Residue Analysis ◽  
Electron Capture Detection ◽  
Relative Standard ◽  
Wide Range ◽  
Repeatability And Reproducibility

A multiresidue method for the simultaneous determination of 22 organochlorine (OCs) and organophosphorus (Ops) pesticides (including isomers and metabolites), representing a wide range of physicochemical properties, was developed in fatty matrices extracted from meat. Pesticides were extracted from samples with acetonitrile/n-hexane (v :v, 1:1). The analytical screening was performed by gas chromatography coupled with electron-capture detection (ECD). The identification of compounds was based on their retention time and on comparison of the primary and secondary ions. The optimized method was validated by determining accuracy (recovery percentages), precision (repeatability and reproducibility), and sensitivity (detection and quantitation limits) from analyses of samples fortified at 38 to 300 ng/g levels. Correlation coefficients for the 22 extracted pesticide standard curves (linear regression analysis, n = 3) ranged from 0.998 to 1.000. Recovery studies from 2 g samples fortified at 3 levels demonstrated that the GC-ECD method provides 64.4-96.0% recovery for all pesticides except 2,4′-DDE (44.6-50.4%), 4,4′-DDE (51.1-57.5%) and 2,4′-DDT (50.0-51.2%). Both repeatability and reproducibility relative standard deviation values were < 20% for all residues. Detection limits ranged from 0.31 to 1.27 ng/g and quantification limits were between 1.04 and 4.25 ng/g. The proposed analytical method may be used as a simple procedure in routine determinations of OCs and Ops in meat. It can also be applied to the determination of pesticide multi-residues in other animal products such as butter and milk.

Sign in / Sign up

Export Citation Format

Share Document