共查询到20条相似文献,搜索用时 328 毫秒
1.
C V Rao 《Biochemical and biophysical research communications》1975,64(1):416-424
The cell membranes isolated from bovine corpora lutea bound 3H-prostaglandin (PG) F2α with high affinity and specificity. The specific binding of 3H-PGF2α was detectable at 10?10M added 3H-PGF2α and reached saturation at 10?7M to 10?6M. Unlabeled PGF2α, as low as 10?9M, inhibited the binding of 3H-PGF2α with complete inhibition occurring at 10?6M. The Scatchard analysis of equilibrium binding data revealed that the PGF2α receptors are heterogeneous: Kd1?5.1 × 10?9M, n?289 fmoles/mg protein; Kd2?1.8 × 10?8M, n?780 fmoles/mg protein. The relative affinities of various other PGs for binding to PGF2α receptors were (PGF2α?100%): PGF1α?17.5; PGE1?0.8; PGE2?22.4; PGA1?0.007; PGB1?0.01. The specificity and affinity of 3H-PGF2α binding is consistent with the possibility that this receptor interaction may reflect an initial event in the action of PGF2α as a luteolytic agent. 相似文献
2.
A charcoal adsorption method was developed to measure specific prostaglandin binding in low speed supernates of hamster myometrial homogenates. This method was used to characterize and quantitate PGE1-specific binding. The equilibrium binding constants and the concentration of specific PGE1 binding sites were determined during the hamster estrous cycle. The apparent association constant for 12 different preparations was 1.16 ± 0.08 × 109M−1. The concentration of PGE1 specific binding sites was significantly higher on Days 2 and 3 of the estrous cycle than it was on Days 1 or 4. The competition for PGE1 binding sites by PGE2, PGF2α, PGA1 and various PGE1 metabolites and derivatives was measured in hamster myometrial homogenates. Relative affinities of the natural prostaglandins for the PGE1 binding sites, calculated by parallel line assay, were: PGE2>PGE1>PGA1>PGF2α. For PGE1 metabolites the relative affinities were: PGE1>13,14-dihydro-PGE1>13,14-dihydro-15-keto-PGE1>15-keto-PGE1. For the analogs and derivatives the compounds tested ranked as: 16,16-dimethyl-PGE1≥PGE1>PGE1 methyl ester>17-phenyl-18,19,20-trinor-PGE1>15(S)15-methyl-PGE1 methyl ester. Arachidonic acid, bis-homo-γ-linolenic acid and 7-oxa-13 prostynoic acid had relative affinities ≥0.1 compared to PGE1=100. Indomethacin had a relative affinity of 0.4 compared to PGE1. 相似文献
3.
We have recently reported that cartilage has two sites for prostaglandin (PG) action. One site (S1) is stimulated by PGA1, PGE1 and PGF1α and elevates tissue cyclic 3′5′adenosine monophosphate (cAMP). A second site (S2) is activated by PGA1 (but not PGE1 or PGF1α) and inhibits the synthesis of cartilage macromolecules. The present study is an investigation of the effects of PGB1 on embryonic chicken cartilage chondromucoprotein synthesis in vitro. PGB1 was found to inhibit chondromucoprotein synthesis with an apparent affinity for S2 which was similar to that of PGA1. The maximal inhibition produced by PGB1 was, however, approximately one-half the maximal inhibition caused by PGA1. Studies of the combined effects of PGB1 and PGA1 were consistent with the hypothesis that both classes of prostaglandins act at a common site (S2) with about equal affinity but that PGB1 has a lower intrinsic activity than PGA1. Similar studies of the combined effects of PGE1 or PGF1α with PGA1 indicate that neither PGE1 nor PGF1α binds significantly to S2. An independent effect of PGB1 to activate S1 and elevate tissue cAMP was also found. 相似文献
4.
M.W. Anderson T.E. Eling J. Guthrie H. Hawkins 《Prostaglandins & other lipid mediators》1976,11(4):645-677
We have investigated the mechanism(s) involved in the removal of prostaglandins (PG) from the pulmonary circulation by the lung. Unidirectional fluxes of PG from the circulation into the lung are measured in an isolated perfused rat lung preparation. Evidence is presented which suggests that a transport system for PG exists in lung tissue. This transport system is responsible for the removal of some PG from the circulation by the lung. PGE1 and PGF2α are substrates for this system, whereas PGB1, PGA1, and 15-keto-PGF2α are not. Since PGA1 is a substrate for the intracellular PG dehydrogenase, the selectivity of the lung's metabolism system for circulating PG is probably due to the selectivity of the transport system for PG. It is shown that the percentage of the pulmonary arterial concentration (CA) of PGE1 or PGF2α that is metabolized on passage through the pulmonary circulation decreases rapidly as CA increases. When the lungs were perfused with PGE1 (PGF2α), the metabolites detected in the venous effluent were 15-keto-PGE1 (PGF2α) and 15-keto-13,14-dihydro-PGE1 (PGF2α). The time course pattern of the appearance of metabolites in the venous effluent after the initiation of a constant CA, and the relative concentrations of the metabolites in the venous effluent, were examined as a function of CA. 相似文献
5.
D.P. Cardinali M.N. Ritta N.S. Speziale M.F. Gimeno 《Prostaglandins & other lipid mediators》1979,18(4):577-589
Incubated bovine pineal glands released prostaglandin E- and prostaglandin F-like material (304 ± 20 and 582 ± 56 pg/mg dry tissue wt/h, respectively) and the release was increased 2.2 2.9-fold by adding 10−4–10−6M of norepinephrine to the medium. Binding assays revealed the existence of high affinity binding of 3H-prostaglandin E2 (3H-PGE2) and 3H-prostaglandin F2α (3H-PGF2α) in low speed supernatants of pineal homogenates. Binding was increased by increasing Ca++ concentration in medium up to 2 mM, was heat-labile and was depressed following incubation with trypsin. In subcellular fractionation studies maximal 3H-PG binding was found in the 27000 × g pellet. Scatchard analysis of 3H-PGE2 binding revealed the presence of a single population of binding sites with a Kd= 1.2 nM and a binding site concentration of 1–2 pmoles/g protein. A single population of binding sites for 3H-PGF2α was also detected with a Kd= 1.7 nM and a similar binding site concentration. Non-radioactive PGE1 and PGE2 were almost equally effective to compete for 3H-PGE2 binding sites (ED50= 5 and 2 nM, respectively). Unlabeled PGF2 was relatively ineffective to compete for 3H-PGE2 binding (ED50>1000 nM) but displaced effectively 3H-PGF2α binding (ED50= 1.2 nM). 相似文献
6.
《Prostaglandins and medicine》1980,4(4):227-237
Cyclooxygenase products of arachidonic acid metabolism in the plasma of normal rabbits and animals bearing the VX2 carcinoma were separated by high performance liquid chromatography and the effluent fractions assayed by serologic methods. The products measured were 6-keto-PGFlα, thromboxane B2, PGE2, PGF2α, 13,14-dihydro-PGE2, 13,14-dihydro-15-keto-PGE2, 15-keto-PGE2, and 13,4-dihydro-15-keto-PGF2α. In hypercalcemic, tumor-bearing rabbts, the plasma concentrations o 13,14-dihydro-15-keto-PGE2 and 13,14-dihydro-15-keto-PGF2α were markedly elevated (in the range of 0.5 to 16 ng/ml). Previously unmeasured 6-keto-PGF1α, thromboxape B2, 13,14-dihydro-PGE2 and 15-keto-PGE2 were not found in high concentrations in the plasma of tumor-bearing rabbits. These results add further support to our conclusion that the VX2 tumor produces hypercalcemia in the host by a mechanism which utilizes PGE2, rather than a subsequent metabolite of this prostaglandin, as the mediator between the neoplasm and bone. 相似文献
7.
《Prostaglandins, Leukotrienes and Medicine》1982,8(3):191-198
Mammary tumors induced in Buffalo rats by treatment with nitrosomethyl urea will regress after oophorectomy. Their ability to synthesize and bind prostaglandins E and F2α was studied in the growing and regressing states. Prostaglandins present in suspensions of 100,000 xg tumor membranes after 2 hr incubation at 37°C ± 5×10−4M indomethacin were partially purified by silica gel column chromatography before assay by specific PG RIA. The amounts of PGE and F2α synthesized rose from 0.13 and 10.5 ng/mg protein in the growing tumors to a maximum of 1.2 and 26.5 ng/mg protein 5 days after oophorectomy. Specific binding of 3H-PGE2 and 3H-PGF2α to 15,000 xg tumor membranes was achieved during a 45 min incubation at 23°C ± excess unlabelled PG. Free and bound prostaglandins were separated by filtration. Binding reached equilibrium after 30 min, was saturable and reversible. Scatchard analysis revealed high affinity binding of PGF2α but only low affinity PGE2 binding in membranes obtained from growing tumors. A 2–3-fold increase in specific binding of PGE2 and PGF2α was noted at 4 days after oophorectomy which represented an increase in the number of PGF2α receptors. PGE2 binding retained a low affinity character. The elevated PGF2α synthesis rates observed in the regressing tumors coupled with a regression-associated increase in receptor number suggests that PGF2α-plays a significant role in hormone-dependent mammary tumor regression. 相似文献
8.
Patricia A. Craven Frederick R. DeRubertis 《Prostaglandins & other lipid mediators》1983,26(4):583-604
Prostaglandin (PG) synthesis and degradation were examined in different regions (epithelial versus non-epithelial structures) of the rat distal colon by both HPLC analysis of [14C] arachidonate (AA) metabolites and by specific radioimmunoassays. Intact isolated colonic epithelial cells synthesized mainly PGF2α and TXA2, as monitored from the formation of its stable degradation product TXB2 (PGF2α > TXB2 > 6-keto-PGF1α, the stable degradation product of PGI2=PGD2=PGE2=13,14-dihydro-15-keto-PGF2α). The profile of PG products of isolated surface epithelial cells was identical to that of proliferative epithelial cells. However, generation of PGs by surface epithelium was 2 to 3-fold higher than by proliferative cells both basally and in the presence of a maximal stimulating concentration (0.1 mM) of AA. The latter implied a greater synthetic capacity of surface epithelium, rather than differences due to endogenous AA availability. The major sites of PG synthesis in colon clearly resided in submucosal structures; the residual colon devoid of epithelial cells accounted for at least 99% of the total PGs produced by intact distal colon. The profile of AA metabolites formed by submucosal structures also differed markedly from that of the epithelium. The dominant submucosal product was PGE2. PGE2 and its degradation product 13,14-dihydro-15-keto-PGE2 accounted for 63% of the PG products formed by submucosal structures (PGE2 PGD2 > 13,14-dihydro-15-keto-PGE2 > PGF2α=TXB2=6-keto-PGF1α > 13,14-dihydro- 15-keto-PGF2α). By contrast, epithelial cells, and particularly surface epithelium, contributed disproportionately to the PG degradative capacity of colon, as assessed from the metabolism of either PGE2 or PGF2α. When expressed as a percentage, epithelial cells accounted for 71% of total colonic PGE2 degradative capacity but only 23% of total colonic protein. Approximately 15% of [3H] PGE2 added to the serosal side of everted colonic loops crossed to the mucosal side intact. Thus, at least a portion of the PGE2 formed in the submucosa reaches, and thereby can potentially influence functions of the epithelium. 相似文献
9.
A method is described for measurement of the cyclooxygenase products, thromboxane,prostacyclin, and prostaglandins (PG), and several prostaglandin metabolites. The procedure involves separation of the compounds by high-pressure liquid chromatography combined with identification and estimation by serologic analysis. These combined procedures have been used to identify and estimate five such products, PGE2, PGE1 PGF2α, PGF1α, and 6-keto-PGF1α, in the culture fluids of dog kidney cells stimulated by a tumor-promoting phorbol diester. The prostaglandin metabolites, 13,14-dihydro-15-keto-PGE2, 13,14-dihydro-15-keto-PF22α, 13,14-dihydro-PGE2, and 13,14-dihydro-PGF2α, were not found in these culture fluids. 相似文献
10.
Human serum binds PGA1 > PGE1 > PGF2α. This is in inverse order of their polarity. Approximately 90% of PGA1 is bound. By analogy with steroid and iodothyronine metabolism, it is likely that the tighter binding of PGA1 accounts for its relatively slow clearance. 相似文献
11.
Alicia Terragno Rachelle Rydzik Norberto A. Terragno 《Prostaglandins & other lipid mediators》1981,21(1):101-112
A fast and reliable method for the separation and quantitation of arachidonic acid metabolites PGF1α, PGF2α, PGD2, PGE1, PGE2, PGB2, PGA2, 6-keto PGE1, 6-keto PGF1α, T×B2 and 15-keto PGE2 by high-performance liquid chromatography has been developed. Utilizing a single reverse-phase column and a UV spectrophotometer, sensitivity as little as 30 nanograms of each of these prostaglandins can be separated and subsequently detected. Although this study was performed using standards, it is highly promising for future application to biological fluids. 相似文献
12.
[3H]Prostaglandin (PG) E2 bound specifically to several subcellular fractions from bovine myometrium. The binding was temperature dependent, rapid, and reversible. PGE2 and PGE1 competed for the [3H]PGE2 binding site. The PGs inhibited in the following decreasing order: PGE2 = PGE1 ? PGF2α > PGA2 > PGF1β > PGB2. No competitive effect could be found for oxytocin. Scatchard analysis of the binding data were interpreted as showing a single high-affinity binding constant. There was no difference in the binding constant between the various fractions. The average molar dissociation constant was 2.74 ± 0.14 × 10?9. Quantitative differences in the maximum number of binding sites were observed between fractions. One plasma membrane fraction contained 21.4 ± 2.3 × 10?11 and the sarcoplasmic reticulum contained 11.2 ± 0.8 × 10?11 mol binding sites/g. The results suggest that there is a high-affinity PGE2 receptor present in both plasma membrane and sarcoplasmic reticulum. 相似文献
13.
S.L. Davis M.S. Anfinson J. Klindt D.L. Ohlson 《Prostaglandins & other lipid mediators》1977,13(6):1209-1220
A series of experiments were conducted in ewes and wether (castrate male) lambs to evaluate the influence of prostaglandins on secretion of anabolic hormones and to determine if repeated injections of prostaglandin (PG) F2α would chronically influence the secretion of these hormones and perhaps growth rate as well.A single intravenous injection of PGA1 and PGB1 (100 μg/kg) exerted no significant (P > .10) influence on plasma concentrations of prolactin (PRL), growth hormone (GH) or thyrotropin (TSH) in ewes. PGA1, but not PGB1, stimulated an increase in the plasma concentration of insulin. Infusion of PGF2α for 5.5 hr into ewes resulted in increased (P < .05) plasma concentrations of both GH and PRL while TSH and insulin were not significantly influenced. Prostaglandin F2α, when injected subcutaneously into wether lambs (10 mg twice weekly) stimulated (P < .05) plasma GH concentrations after the first injection, but not after 3 weeks of treatment. Changes in plasma PRL or TSH were not observed consistently in the lambs treated chronically with PGF2α or TRH.Prostaglandin F2α, in the present studies, and PGE1 in previously reported studies (1–3), has been demonstrated to be stimulatory to the secretion of PRL and GH. In contrast, PGA1 and PGB1, which lack an 11-hydroxyl group, failed to influence the secretion of either PRL or GH. It would, therefore, appear that the 11-hydroxyl group is a structural requirement for prostaglandins to influence the secretion of these two hormones in sheep.Treatment with thyrotropin releasing hormone (TRH), alone or in combination with PGF2α, significantly (P < .05) increased growth rate (average daily gains) while PGF2α did not, despite the fact that both compounds exerted similar effects on plasma GH. 相似文献
14.
M. Viggiano A.M. Franchi A. Faletti M.A.F. Gimeno A.L. Gimeno 《Prostaglandins & other lipid mediators》1988,36(3)
The effects of exogenous histamine (H) on prostaglandin (PG) generation and release in uteri isolated from diestrous rats and the influences of H2-receptors blockers (cimetidine and mitiamide) on the output of uterine PGs, were explored. Moreover, the action of H on the uterine 9-keto-reductase, was also studied. Histamine (10−4M) failed to alter the basal output of PGE1 but reduced significantly the generation and release of PGE2 and augmented the output of PGF2α. On the other hand, cimetidine (10−5M) enhanced the basal release of PGE2 but had no action on the outputs of PGs E1 or F2α. The enhancing effect of H on the production and release of PGF2α was abolished in the presence of cimetidine. Also, the antagonist reversed the influence of H on the output of PGE2. Metiamide, another H2-receptor antagonist, did not alter the basal control generation and release of uterine PGs, but antagonized the augmenting influence of H on PGF2α uterine output, as much as cimetidine did, and prevented the depressive action of H on the release of PGE2 from uteri. Histamine (10−4M) significantly stimulated uterine formation of cyclic-adenosine monophosphate, an action which was antagonized by the presence of cimetidine (10−5M), a blocker of H2 receptors. Also, histamine (10−5M) and dibutyril-cyclic-adenosine monophosphate (DB-cAMP) at 10−3M, enhanced significantly the formation 3H-PGF2α from 3H-PGE2. Results presented herein demonstrate that H is able to diminish the generation of PGE2 in uteri from rats at diestrus augmenting the synthesis of PGF2α, apparently via the activation of H2-receptors, enhancing adenylate-cyclase. These effects appear to increase uterine 9-keto-reductase activity which transforms PGE2 into PGF2α. Relationships between the foregoing results and those evoked by estradiol, are also discussed. 相似文献
15.
Ch.V. Rao 《Prostaglandins & other lipid mediators》1973,4(4):567-576
The cell membranes exhibited specific binding to 3H-prostaglandin E1 (3H-PGE1) and 125I-human chorionic gonadotropin (125I-HCG). Unlabeled PGE1,PGE2 (1.4 × 10?7M), PGF1α and PGF2α (1.4 × 10?5M) decreased 3H-PGE1 binding by more than 80%. The binding of 125I-HCG was completely inhibited by 5 × 10?8M unlabeled HCG. However, the unlabeled PGE1 (1.15 × 10?6M) and HCG (8.4 × 10?7M) had no effect on 125I-HCG and 3H-PGE1 binding respectively. A PG antagonist, 7-oxa-13-prostynoic acid, inhibited only 3H-PGE1 binding but not 125I-HCG binding. These results suggest the presence of specific receptors for PGE1 and HCG in the cell membranes and that the binding occurs either at two different sites on the same receptor or that each binds to a “different” receptor molecule. 相似文献
16.
Preliminary studies indicate the presence of PGF2α specific binding sites in membrane fractions prepared from equine corpora lutea. The equilibrium binding data indicate an apparent dissociation constant of 3.2 × 10?9M and the concentration of binding sites of ~0.1 pmoles/mg membrane protein. Competition of several natural prostaglandins for equine luteal PGF2α specific binding sites indicates specificity for the 9α-hydroxyl moiety and the 5,6-cis doublebond. Significant increases in relative binding affinities were demonstrated for PGF2α analogs with a phenyl ring introduced at carbons 16 or 17. Specific PGF2α binding was demonstrated in corpora lutea collected at known stages of the estrous cycle. There was no pattern in these values based on the stage of the cycle. While specific 3H-PGE1 binding could be demonstrated, no high affinity sites could be quantitated. 3H-PGE1 binding appeared unaffected by changes in temperature or time of incubation, whereas PGF2α specific binding was significantly modified by both these factors. 相似文献
17.
Walter D. Cantarow Hou Tak Cheung G. Sundharadas 《Prostaglandins & other lipid mediators》1978,16(1):39-46
The effects of prostaglandins on the
properties of mouse peritoneal macrophages namely spreading, adhesion and migration were investigated. PGE1 and PGE2 inhibit the spreading and adhesion of complete Freund's Adjuvant induced peritoneal macrophages significantly at concentrations of 1 ng per ml and above whereas they enhance the migration of these cells at concentrations of 100 ng per ml and above. PGA2 and PGB2 are less potent as they inhibit spreading and adhesion only at a concentration of 1 μg per ml. At this concentration PGB2 enhances migration whereas PGA2 has no effect. PGF2α has no effect on the spreading, adhesion and migration of macrophages in the concentration range of 0.1 ng to 1,000 ng per ml. 相似文献
18.
J.C. Cornette K.T. Kirton W.P. Schneider F.F. Sun R.A. Johnson E.G. Nidy 《Prostaglandins & other lipid mediators》1975,9(2):323-338
Radioimmunoassay systems are described which have been developed to quantitate two principle urinary metabolites of PGF2α; 9α,11α-dihydroxy-15-oxo-2,3,4,5-tetranorprostanoic acid (I) and 9α-11α-dihydroxy-15-oxo-2,3,4,5-tetranorprosta-1,20-dioic acid (II). Preparation of the required metabolites was achieved by total synthesis (I) or by bioconversion (isolation from urine of animals treated with 15-keto-PGF2α*, II). These metabolites were used to prepare conjugates for immunization. Labeled metabolites, suitable as binding markers, were prepared by metabolism of 3H-PGF2α
(I) or
(II). Specificity of the resulting antibodies was compared to an antibody to PGF2α and to 13,14-dihydro-15-keto PGF2α. Antisera of II had little or no affinity for 20-carbon precursors (PGF2α or 13,14-dihydro-15-keto PGF2α), but had nearly equal affinity for metabolite I. Antisera of I, however, had little or no affinity for antigen of II. Therefore, analysis of samples by both assay systems enables quantitation of these excretion products of PGF2α. Other assay parameters (binding, affinity, recovery, precision and the repeatability of the assays) were similar to those previously described for other RIA systems, and were considered satisfactory for quanitation of compounds in biological fluids.Quantitation of 24 hour urinary excretion of di-acid metabolite in humans was in close agreement with previously published values determined by physical-chemical means. Greater quantity of di-acid metabolite was excreted by human males (42.0 μg/24 hr) than by females sampled either during the follicular (20.0) or luteal phase (21.2) of the menstrual cycle. The total quantity of C-16 metabolites (as approximated by system II) excreted/kg body weight by the rhesus monkey was similar to that excreted by the human. However, the ratio of di-acid to mono-acid was much nearer unity in the monkey than the human. 相似文献
19.
Antibodies against 15 keto PGF2α and 13,14 dihydro 15 keto PGF2α were produced in goats and rabbits using the appropriate prostaglandin protein conjugate. Tritium labeled 15-keto, and 13,14 dihydro 15-keto PGF2α were prepared from 3H-PGF2α. These antibodies and 3H-labeled compounds were used to develop radioimmunoassays for the respective F2α metabolites. The antibodies had relatively little cross-reactivity (≤0.1%) with the parent F2α molecule. Infusion of PGF2α in monkeys increased 15-keto-h2 levels 10–20 fold higher than PGF2α in peripheral plasma. The levels of this metabolite were not altered detectably during clotting, indicating relatively slow rates of PGF2α metabolism in vitro. These assays should be useful to follow release rates of exogenous prostaglandins from various formulations and delivery systems, and in vivo tissue synthesis of PGF2α, where low levels preclude measuring the parent compound. 相似文献
20.
Intact viable bovine luteal cell suspensions prepared by collagenase digestion of luteal tissue were used in studying the selected properties of [3H] prostaglandin (PG) F2α binding and compared with those observed in plasma membranes. [3H]PGF2α specific binding to luteal cells was a rapid (K1 = 8.4 × 104M?12αS?1), reversible (K?1 = 1.8 × 10?4S?1) and saturable process at 24°. There was a single class of receptors with an apparent dissociation constant of 10.6 nM and 1.8 × 105 receptors per cell. The presence of increasing amounts of unlabeled PGs inhibited [3H]PGF2α binding in a dose-dependent manner. The potency order for this inhibition was: (15S) 15-methyl-PGF2α methyl ester > ICI-80,996 > PGF2α > ICI-81,008 > PGF1α > PGE2, (15S) 15-methyl-PGE2 methyl ester > PGF2α metabolites > other PGs, PGF1α metabolites and PGE metabolites. Other than the homegeneous nature of binding and a greater association rate in cells, the rest of the [3H]PGF2α binding properties in cells were in good agreement with those observed in plasma membranes. 相似文献