The interaction between lipid peroxidation and prostaglandin synthesis in rabbit kidney-medulla slices.
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ABSTRACT:
SUBMITTER: Fujimoto Y
PROVIDER: S-EPMC1152025 | biostudies-other | 1983 Apr
REPOSITORIES: biostudies-other
Similar Datasets
Project description:The effect of diarachidonin on the synthesis of prostaglandin E2 in rabbit kidney medulla slices was examined. The addition of diarachidonin stimulated prostaglandin E2 production in a dose-dependent manner. At three concentrations (10, 50 and 100 microM), increases in prostaglandin E2 formation induced by exogenous diarachidonin were 2-fold greater than those induced by exogenous arachidonic acid. Diacylglycerol or phosphatidic acid from egg lecithin had little or no effect on prostaglandin E2 production. Moreover, EGTA failed to inhibit diarachidonin-stimulated prostaglandin E2 formation, indicating that the stimulatory effect of diarachidonin is not mediated through the activation of endogenous phospholipase A2 (including phosphatidic acid-specific phospholipase A2). These results are discussed in the light of our former hypothesis that arachidonic acid release from kidney medulla phospholipids might occur through the sequential action of a phospholipase C coupled to diacylglycerol and monoacylglycerol lipases [Fujimoto, Akamatsu, Hattori & Fujita (1984) Biochem. J. 218, 69-74].
| S-EPMC1152930 | biostudies-other
Project description:We have investigated the effects of phospholipase A2 and C on the synthesis of prostaglandin E2 in rabbit kidney medulla and the release of fatty acids from the medulla slices. Exogenous phospholipase A2 [from Naja naja (Indian cobra) venom] and phospholipase C (from Clostridium welchii) stimulated prostaglandin E2 production in a dose-dependent manner. At the maximal effective concentrations (0.5 unit of phospholipase A2/ml, 2 units of phospholipase C/ml), phospholipase C increased prostaglandin E2 formation to the level observed with phospholipase A2. Phospholipase A2 enhanced the release only of unsaturated fatty acids, whereas phospholipase C stimulated the release of individual free fatty acids (C 16:0, C 18:0, C 18:1, C 18:2 and C 20:4). Moreover, p-bromophenacyl bromide inhibited phospholipase A2-stimulated prostaglandin E2 production and the release of fatty acids, but it had no influence on prostaglandin E2 formation and the release of fatty acids increased by phospholipase C, indicating that the stimulatory effect of phospholipase C is not mediated through the activation of endogenous phospholipase A2. These results suggest the presence of diacylglycerol lipase and monoacylglycerol lipase in the kidney and the importance of this pathway in prostaglandin synthesis by the kidney.
| S-EPMC1153308 | biostudies-other
Project description:The bivalent cations Ca2+, Mg2+, Co2+, Mn2+, Sr2+ and Ba2+ were compared for their stimulatory or inhibitory effect on prostaglandin formation in rabbit kidney medulla slices. Ca2+, Mn2+ and Sr2+ ions stimulated prostaglandin generation up to 3--5-fold in a time- and dose-dependent manner (Ca2+ greater than Mn2+ congruent to Sr2+). The stimulation by Mn2+ (but not by Sr2+) was also observed in incubations of medulla slices in the presence of Ca2+. Mg2+ and Co2+ ions were without significant effects on either basal or Ca2+-stimulated prostaglandin synthesis. The stimulatory effects of Ca2+, Mn2+ and Sr2+ on medullary generation of prostaglandin E2 were found to correlate with their stimulatory effects on the release of arachidonic acid and linoleic acid from tissue lipids. The release of other fatty acids was unaffected, except for a small increase in oleic acid release. As both arachidonic acid and linoleic acid are predominantly found in the 2-position of the glycerol moiety of phospholipids, the stimulation by these cations of prostaglandin E2 formation appears to be mediated via stimulation of phospholipase A2 activity.
| S-EPMC1161417 | biostudies-other
Project description:Three separate prostaglandin-generating activities are associated with plasma membranes, mitochondria and microsomal fractions from rabbit kidney medulla. In the plasma membranes and mitochondria, but not in microsomal fractions, Ca2+ ions stimulate the activity of phospholipase A2, yielding selective release of arachidonic acid and linoleic acid and concomitant increase in prostaglandin E2 formation.
| S-EPMC1162833 | biostudies-other
Project description:A simple radioactive-substrate assay for prostaglandin synthase (EC 1.14.99.1), which uses t.l.c. to measure simultaneously different prostaglandins synthesized from one precursor substrate, was developed. Rabbit kidney-medulla prostaglandin synthase catalyses the formation of prostaglandin E2, prostaglandin F2alpha and prostaglandin D2 from arachidonic acid. Fractionation of crude homogenates indicated that the microsomal fraction possessed the highest specific activity of prostaglandin synthase, whereas the soluble fraction exhibited little enzyme activity but rather contained a heat-labile inhibitory macromolecular factor(s), which might be attributed to the serum albumin present in this fraction. The microsomal fraction possessed low intrinsic enzyme activity, but the actvity could be fully stimulated by the presence of both GSH (reduced glutathione) and a phenolic cofactor. Only cysteine could partially replace GSH, whereas other thiols were inactive and some were even inhibitory. A variety of phenolic compounds, including catecholamines, dopamine (3,4-dihydroxyphenethylamine), 5-hydroxytryptamine and quinol, were active in stimulating prostaglandin synthase. In all cases, the stimulation was reflected in the synthesis of all three prostaglandins with ratios not significantly altered by different phenolic cofactors. The synthesis of each of the different prostaglandins appeared to have similar pH optima. The enzyme system was not inhibited by thiol-group inhibitors or a variety of metal chelators except for cyanide and 8-hydroxyquinoline. Characterization of the kidney-medulla prostaglandin synthase system indicated that it exhibited properties similar to those of the enzyme system present in seminal vesicles.
| S-EPMC1172705 | biostudies-other
Project description:Lipid peroxidation and DNA damage were evaluated in liver slices incubated for 2 h at 37 degrees C with 1 mM-t-butyl hydroperoxide (t-BOOH), 1 mM-BrCCl3 or 50 microM-ferrous iron. t-BOOH induced the greatest amount of damage to DNA and increased the production of thiobarbituric acid-reactive substances (TBARS). Both phenomena depended on the incubation time. Ferrous iron induced both DNA damage and TBARS production, and BrCCl3 did not induce significant DNA damage and was the weakest TBARS inducer. Butylated hydroxytoluene at 1 mM inhibited both DNA damage and TBARS production. DNA damage and lipid peroxidation in liver slices were correlated, indicating that these events were concurrent.
| S-EPMC1149231 | biostudies-other
Project description:A great variety of compounds are formed during lipid peroxidation of polyunsaturated fatty acids of membrane phospholipids. Among them, bioactive aldehydes, such as 4-hydroxyalkenals, malondialdehyde (MDA) and acrolein, have received particular attention since they have been considered as toxic messengers that can propagate and amplify oxidative injury. In the 4-hydroxyalkenal class, 4-hydroxy-2-nonenal (HNE) is the most intensively studied aldehyde, in relation not only to its toxic function, but also to its physiological role. Indeed, HNE can be found at low concentrations in human tissues and plasma and participates in the control of biological processes, such as signal transduction, cell proliferation, and differentiation. Moreover, at low doses, HNE exerts an anti-cancer effect, by inhibiting cell proliferation, angiogenesis, cell adhesion and by inducing differentiation and/or apoptosis in various tumor cell lines. It is very likely that a substantial fraction of the effects observed in cellular responses, induced by HNE and related aldehydes, be mediated by their interaction with proteins, resulting in the formation of covalent adducts or in the modulation of their expression and/or activity. In this review we focus on membrane proteins affected by lipid peroxidation-derived aldehydes, under physiological and pathological conditions.
| S-EPMC3761222 | biostudies-literature
Project description:Microsomal prostaglandin synthase (EC 1.14.99.1) from rabbit kidney medulla was assayed with [5,6,8,9,11,12,14,15-3H]-and [1-14C]-arachidonic acid as the substrate. The ratios of prostaglandin F2 alpha to prostaglandin E2 and to prostaglandin D2 were determined by both 3H and 14C labelling. When 3H was used as a label the ratios were much higher than with 14C labelling indicating that the removal of hydrogen at C-9 or C-11 was the rate-limiting step in the biosynthesis of prostaglandin E2 or prostaglandin D2. This finding shows that the octatritiated arachidonic acid is not the appropriate substrate marker for studying the regulation of the synthesis of different prostaglandins by various agents. When the enzyme assay was carried out in the presence of SnCL2, which was capable of accumulating exclusively prostaglandin F2alpha at the expenses of prostaglandin E2 and prostaglandin D2, the addition of L-adrenaline to the microsomal fraction either alone or with reduced glutathione equally stimulated the formation of prostaglandin F2alpha, whereas the addition of reduced glutathione to the microsomal fraction either alone or with L-adrenaline produced no additional effect. These results suggest that endoperoxide is formed as the common intermediate for the biosynthesis of three different prostaglandins in rabbit kidney medulla, and that L-adrenaline stimulates the synthesis of endoperoxide, whereas reduced glutathione facilitates the formation of prostaglandins from endoperoxide.
| S-EPMC1164272 | biostudies-other
Project description:We have recently shown that mitochondrial and plasma-membrane fractions from kidney medulla possess Ca(2+)-stimulated acylhydrolase and prostaglandin synthase activities. The nature of the enzymic coupling between the Ca(2+)-stimulated arachidonic acid release and its subsequent conversion into prostaglandins was investigated in subcellular fractions from rabbit kidney medulla. Plasma-membrane, mitochondrial and microsomal fractions were found to have similar apparent K(m) values for conversion of added exogenous arachidonate into prostaglandins. The rate of prostaglandin biosynthesis (V(max.)) from added arachidonic acid in the microsomal fraction was approx. 2-fold higher than in the other subcellular fractions. In contrast, prostaglandin E(2) synthesis from endogenous arachidonate in plasma-membrane and mitochondrial fractions was 3-4-fold higher than in microsomes. Furthermore, Ca(2+) stimulated endogenous arachidonate deacylation and prostaglandin E(2) generation in the former two fractions but not in microsomes. In mitochondrial or crude plasma-membrane fractions, in which prostaglandin biosynthesis was inhibited with aspirin, arachidonate released from these fractions was converted into prostaglandins by the microsomal prostaglandin synthase. Thus an intracellular prostaglandin generation process that involves inter-fraction transfer of arachidonic acid can operate. Prostaglandin generation by such an inter-fraction process is, however, less efficient than by an intra-fraction process, where arachidonic acid released by mitochondria or crude plasma membranes is converted into prostaglandins by prostaglandin synthase present in the same fraction. This demonstrates the presence of a tight intra-fraction enzymic coupling between Ca(2+)-stimulated acylhydrolase and prostaglandin synthase enzyme systems in both mitochondrial and plasma-membrane fractions.
| S-EPMC1163691 | biostudies-other
Project description:Oxidative stress is elevated in numerous environmental exposures and diseases. Millions of dollars have been spent to try to ameliorate this damaging process using anti-oxidant therapies. Currently, the best accepted biomarker of oxidative stress is the lipid oxidation product 8-iso-prostaglandin F2? (8-iso-PGF2?), which has been measured in over a thousand human and animal studies. 8-iso-PGF2? generation has been exclusively attributed to nonenzymatic chemical lipid peroxidation (CLP). However, 8-iso-PGF2? can also be produced enzymatically by prostaglandin-endoperoxide synthases (PGHS) in vivo. When failing to account for PGHS-dependent generation, 8-iso-PGF2? cannot be interpreted as a selective biomarker of oxidative stress. We investigated the formation of 8-iso-PGF2? in rats exposed to carbon tetrachloride (CCl4) or lipopolysaccharide (LPS) using the 8-iso-PGF2?/PGF2? ratio to quantitatively determine the source(s) of 8-iso-PGF2?. Upon exposure to a 120mg/kg dose of CCl4, the contribution of CLP accounted for only 55.6±19.4% of measured 8-iso-PGF2?, whereas in the 1200mg/kg dose, CLP was the predominant source of 8-iso-PGF2? (86.6±8.0% of total). In contrast to CCl4, exposure to 0.5mg/kg LPS was characterized by a significant increase in both the contribution of PGHS (59.5±7.0) and CLP (40.5±14.0%). In conclusion, significant generation of 8-iso-PGF2? occurs through enzymatic as well as chemical lipid peroxidation. The distribution of the contribution is dependent on the exposure agent as well as the dose. The 8-iso-PGF2?/PGF2? ratio accurately determines the source of 8-iso-PGF2? and provides an absolute measure of oxidative stress in vivo.
| S-EPMC6626672 | biostudies-literature