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1.
O. E. Grichenko V. V. Shaposhnikova A. A. Kudryavtsev Yu. N. Korystov 《Biology Bulletin》2004,31(3):221-225
We studied the effect of specific inhibitors of 5- and 12-lipoxygenases as well as the product of cyclooxygenase activity, prostaglandin E2, on proliferation and death of P388 leukemia cells. Inhibition of 5- and 12-lipoxygenases in the cells inhibits proliferation and induces apoptosis. The concentrations of baicalein, an inhibitor of 12-lipoxygenase, and AA861, an inhibitor of 5-lipoxygenase, causing a 50% death rate (LC50) proved to be the same, 50 M. Excessive prostaglandin also inhibited proliferation of the cells and induced apoptosis. The LC50 for prostaglandin E2 was 4 M. The obtained data suggest that apoptosis in P388 cells after lipoxygenase inhibition can be induced by both deficiency of lipoxygenase products and excess of prostaglandins in the cell. 相似文献
2.
Summary Pinocytosis induced by Na+ was assayed by phase contrast microscopy in 8–12 days starvedAmoeba proteus. These cultures were inactive with respect to calcium-dependent Na+-induced pinocytosis, but treatment with amino acid methyl and ethyl esters increased their capacity for pinocytosis. Besides promoting pinocytosis these compounds also stimulated calcium-sensitive secretion of lysosomal enzymes from normal, 2–3 days starved, cells. Only uncharged 1-forms of the amino acid esters were effective. Also other lysosomotropic compounds including monodansylcadaverine, glycine-phenylalanine-2-naphthylamide, NH4Cl, and the ionophores monensin and A23187 activated starved cells. The effect of these agents (except A23187) was inhibited by the drug dantrolene suggesting that activation is a consequence of release of Ca2+ from intracellular stores. Several of the lysosomotropic agents also lost their activating effect in the presence of phospholipase A2 (PLA2) inhibitors. To investigate whether or not PLA2 activity in the cell culture could imitate the effect of the lysosomotropic agents, we incubated starved cells with snake venom PLA2s. These enzymes caused rapid, dantrolene-sensitive activation of the cells. Measurement of endogenous PLA2in normal cells revealed significant cellular activity but no significant secretion of the enzyme into the culture medium was observed. Together the studies with enzyme inhibitors and dantrolene suggest that the process by which lysosomotropic agents affect pinocytosis involves activation of PLA2 and release of Ca2+ from intracellular stores.Abbreviations AnBOMe
amino-n-butyric acid methylester
- Et
ethylester
- GPN
glycine-1-phenylalanine-2-naphthylamide
- MDC
monodansylcadaverine
- MDTC
monodansylthiacadaverine
- Me
methylester
- pBPB
p-bromo phenacylbromide
- PLA2
phospholipase A2 相似文献
3.
V. V. Shaposhnikova M. V. Egorova A. A. Kudryavtsev M. Kh. Levitman Yu. N. Korystov 《FEBS letters》1997,410(2-3)
The effect of melittin, an activator of phospholipase A2, on proliferation and death of rat thymocytes in a broad concentration range was studied. Cell proliferation was estimated by the accumulation of colchicin metaphases, necrotic death was determined from lysis and staining of cells with trypan blue, and apoptosis was assessed from the type of DNA fragmentation, the amount of fragmented DNA, and the percentage of cells with subdiploid DNA. It was shown that low melittin concentrations (below 5 μg/ml) stimulate thymocyte proliferation. At high melittin concentrations, thymocytes die by the primary necrosis type. Throughout the concentration range studied, melittin does not produce apoptosis in thymocytes. Conversely, high melittin concentrations even inhibit thymocyte apoptosis in the control and after irradiation. An inhibitor of RNA synthesis actinomycin D does not affect thymocyte death in the presence of melittin. It is concluded that the activation of phospholipase A2 can induce necrosis but not apoptosis and thus is not a necessary step in the signaling cascade that initiates apoptosis in thymocytes. 相似文献
4.
Chang WC Shyu WJ Shi GY Lin MT Jen CJ Wing LY Tang MJ Wu HL 《Journal of biomedical science》1996,3(1):59-66
Treatment of cultured bovine carotid artery endothelial cells with 0.1 µM human plasmin has been reported to induce a receptor-mediated short burst of arachidonate release, which is a pertussis toxin-sensitive and extracellular calcium-dependent reaction. Plasmin-induced calcium influx in cells was significantly inhibited by pretreatment with pertussis toxin, indicating that the former was coupled with a pertussis toxin-sensitive guanosine 5-triphosphate (GTP)-binding protein. Plasmin significantly induced the formation of lysophosphatidylcholine but not lysophosphatidylethanolamine. A cellular phospholipase A2 with an arachidonyl specificity at the sn-2 position of phosphatidylcholine, which required submicromolar calcium, was identified as a cytosolic phospholipase A2 by immunoblot analysis. By a cell-free enzyme activity assay and immunoblot analysis, plasmin was found to induce a translocation of the cytosolic phospholipase A2 from the cytosol to the membrane. Taken together, the results suggest that plasmin bound to its putative receptor and activated a GTP-binding protein coupled to calcium influx channel, followed by translocation and activation of cytosolic phospholipase A2 in endothelial cells. 相似文献
5.
Roland U. Paul andré Holk Günther F. E. Scherer 《The Plant journal : for cell and molecular biology》1998,16(5):601-611
Activation of cytosolic phospholipase A2 is a typical signal transduction reaction in animal cells and occurs in plants in response to auxin, elicitors and wounding. Exogenously added fluorescent bis-BODIPY-phosphatidylcholine was taken up and hydrolysed by a cellular phospholipase A2. Rapid activation of a phospholipase A2 by auxin in suspension-cultured parsley ( Petrosilenum crispum L.) and soybean ( Glycine max L.) cells was shown by detection and quantification of fluorescent reaction products of phospholipase A2. Hormone-triggered fluorescent fatty acid accumulation could be detected as early as 5 min. Auxins at 2 μM or higher concentrations activated phospholipase A2 and fluorescent fatty acids accumulated 1.1- to threefold after 90–120 min, depending on the auxin concentration. Fluorescent lysolipid did not accumulate up to 150 μM auxin. Known inhibitors of phospholipase A2 inhibited hormone-dependent fluorescent fatty acid accumulation in cell cultures and, previously, elongation growth in etiolated zucchini hypocotyl segments ( Scherer & Arnold (1997 ) Planta 202, 462–469). When lipids were labeled by [14C]-choline and [14C]-ethanolamine the corresponding lysophospholipids could be quantified in cell extracts. Radioactive lysophospholipids accumulated as rapidly as 1–2 min after auxin treatment but only at concentrations well above 100 μM auxin. We hypothesize that phospholipase A2 activation is an early intermediate step between receptor and downstream responses. We hypothesize that fatty acid(s) could be second messengers in several auxin functions, especially in cell elongation. Lysophospholipids seem to be indicators or second messengers for stress caused by high auxin concentrations or may have different auxin-linked functions and are also known to accumulate during elicitor action. 相似文献
6.
Garnham BM Fitzpatrick-Wong S Schunack W Nürnberg B Sorrentino G Parkinson FE Kanfer JN Sitar DS 《Neurochemical research》2002,27(12):1613-1618
Compound 24, an alkyl-substituted amino acid amide, previously found to activate pertussis toxin-sensitive G proteins in cell membranes and membrane protein fractions, was used as a tool to determine the mechanism/location of nicotine inhibition of amyloid peptide-stimulated phospholipase A2 and D activities in a human neuroblastoma cell line, LA-N-2, in vitro. In contrast to our previous findings with amyloid peptide, these phospholipase activations by compound 24 were not inhibited by (–)-nicotine, cholera toxin or tetanus toxin pretreatment. The contrasting activation of these phospholipases by amyloid peptide and compound 24 are discussed. 相似文献
7.
Abstract: The serotonin 5-HT2C receptor (formerly designated the 5-HT1C receptor) of the choroid plexus triggers phosphoinositide turnover. In the present study, we demonstrate that receptor activation also triggers the formation of cyclic GMP (cGMP). Application of 1 µM 5-HT to porcine choroid plexus tissue slices resulted in stimulation of cGMP formation to a maximum of five-fold basal level, with an EC50 of 11 nM. This response was not inhibited by muscarinic or β-adrenergic receptor antagonists. Serotonin receptor antagonists inhibited cGMP formation with apparent Ki values of 1.3 (mianserin), 200 (ketanserin), and 5,500 (spiperone) nM, respectively. Neither serotonin-stimulated cGMP formation nor PI turnover was inhibited by pertussis toxin pretreatment. Preliminary biochemical studies suggested that serotonin-stimulated cGMP formation was calcium, phospholipase A2, and lipoxygenase dependent, as incubation in low calcium buffers or inclusion of the phospholipase A2 or lipoxygenase inhibitors p-bromophenacyl bromide or BW 755c resulted in significant reduction of cGMP formation. The present results suggest that in addition to triggering phosphoinositide turnover, choroid plexus serotonin 5-HT2C receptors trigger cGMP formation in a calcium-sensitive manner. 相似文献
8.
《Bioscience, biotechnology, and biochemistry》2013,77(5):864-870
Protobothrops flavoviridis venom contains plural phospholipase A2 (PLA2) isozymes. A [Lys49]PLA2 called BPII induced cell death in human leukemia cells. PLA2, an [Asp49]PLA2 that has much stronger lipolytic activity than BPII, failed to induce cell death. BPII-treated cells showed morphological changes, DNA fragmentation, and nuclear condensation. This BPII-induced apoptotic cell death was neither inhibited by inhibitors of caspases 3 and 6 nor accompanied by activation of procaspase 3, indicating that BPII-induced cell death is caspase independent. Since inactive p-bromophenacylated BPII induced cell death, BPII-induced apoptotic cell death is independent of PLA2 lipolytic activity. Rapid externalization of phosphatidylserine in BPII-treated cells was observed for fluorescein isothiocyanate (FITC)-labeled annexin V. In the cells treated with BPII, this spread over the cell membranes, implying that the cell toxicity of BPII is mediated via its cell-surface receptor. 相似文献
9.
T. Finkenstädt N. T. Adler T. O. Allen S. O. E. Ebbesson J. -P. Ewert 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1985,156(4):433-445
Summary The (14C)2DG autoradiographic technique has been employed to quantitatively map glucose utilization in the mesencephalon, the diencephalon and the cerebellum, of toads in response to configurational moving visual stimuli: (i) a 0.4 cm × 2.8 cm worm-like stripe (W) which elicited prey catching responses, (ii) a 8.4 cm × 8.4 cm square (S) that released predator avoidance responses, and (iii) a 2.8 cm × 0.4 cm antiworm-like stripe (A) which elicited no motor activity.For various brain nuclei different relationships were obtained: The optic tectum showed statistical significant higher 2DG uptake during worm-stimulation (¯X
W) than during antiworm stimulation (¯X
A), i.e.¯X
W>¯X
A. The latter visual pattern led to a 2DG utilization that was statistically significant stronger than during stimulation with a square (¯X
S), i.e.¯X
A>¯X
S. Thus, in comparison between right and left hemisphere as well as between brains the following ratios were obtained:Optic tectum:¯X
W>¯X
A>¯X
S; nucleus isthmi:¯X
W>¯X
A-¯X
s; posterodorsal lateral thalamic nucleus:¯X
S>¯X
A>¯X
W; posteroventral lateral thalamic nucleus:¯X
S>¯X
A¯X
W; posterior thalamic nucleus:¯X
W>¯X
A¯X
S; anteripr division of the lateral thalamic nucleus:¯X
W>¯X
A¯X
S; anterior thalamic nucleus:¯X
A>¯X
S>¯X
W; nucleus of Bellonci and dorsal division of the ventrolateral thalamic nucleus:¯X
W¯X
A¯X
S; cerebellum:¯X
S¯X
W>¯X
A.Abbreviations
A
anterior thalamic nucleus
-
Cb
cerebellum
-
Hyp
hypothalamus
-
Ist
nucleus isthmi
-
cl. Ist
contralateral Ist
-
La
lateral thalamic nucleus, anterior division
-
Lpd
lateral thalamic nucleus, posterodorsal division
-
Lpv
lateral thalamic nucleus, posteroventral division
-
MP
medial pallium
-
NB/VLd
nucleus of Bellonci and ventrolateral thalamic nucleus, dorsal division
-
P
posterior thalamic nucleus
-
PO
preoptic area
-
Sna
snapping evoking area=ventrolateral tectum
-
Str
striatum
-
Tec
tectum opticum 相似文献
10.
Singh Indrapal N. Sorrentino Giuseppe Kanfer Julian N. 《Neurochemical research》1998,23(10):1225-1232
Amyloid protein is the major protein component of neuritic plaques found in the brain of Alzheimer's disease. The activation of phospholipase D by amyloid beta protein (25–35), quisqualate and phorbol 12, 13-dibutyrate was investigated in LA-N-2 cells by measuring phosphatidylethanol formation. The activation of phospholipase D by quisqualate and AP (25–35) was calcium-independent. The AP (25–35) and quisqualate activation of phospholipase D appeared to be mediated through a pertussis toxin-sensitive GTP-binding protein. Phospholipase D activation by AP (25–35), quisqualate and phorbol dibutyrate was not blunted by the protein kinase C inhibitors, staurosporine, H-7 and RO-31-8220. However, it was abolished by overnight exposure to phorbol dibutyrate. This activation of phospholipase D was prevented by the tyrosine kinase inhibitor, genistein but not by tyrophostin A. Several excitatory amino acid antagonists were tested for their ability to prevent the phospholipase D activation by quisqualate and AP (25–35). Only NBQX was effective with an IC50 of 75 M for AP (25–35) and quisqualate. Activation of phospholipase D by AP or quisqualate was absent in LA-N-2 cells previously desensitized by quisqualate or AP (25–35), but the activation by phorbol dibutyrate was unaltered. The responsiveness to AP and quisqualate in previously desensitized cells reappeared subsequent to a period of resensitization. The observations with the antagonist NBQX, and the desensitization and resensitization experiments, are consistent with a receptor occupancy mediated activation of phospholipase D by quisqualate and by AP (25–35). 相似文献
11.
Alon Margalit Avinoam A. Livne Jørgen Funder Yosef Granot 《The Journal of membrane biology》1993,136(3):303-311
Platelets revert hypotonic-induced swelling by the process of regulatory volume decrease (RVD). We have recently shown that this process is under the control of endogenous hepoxilin A3. In this work, we investigated the mechanical-biochemical transduction that leads to hepoxilin A3 formation. We demonstrate that this process is mediated by pertussis-toxin-sensitive G protein, which activates Ca2+-insensitive phospholipase A2, and the sequential release of arachidonic acid. This conclusion is supported by the following observations: (i) RVD response is blocked selectively by the phospholipase A2 inhibitors manoalide and bromophenacyl-bromide (0.2 and 5
m, respectively) but not by phospholipase C inhibitors. The addition of arachidonic acid overcame this inhibition; (ii) extracellular Ca2+ depletion by EGTA (up to 10 mm) does not affect RVD; (iii) intracellular Ca2+ depletion by BAPTAAM (100
m) inhibits RVD but not hepoxilin A3 formation, as tested by the RVD reconstitution assay; (iv) RVD is inhibited by the G-protein inhibitors, GDP
S (1
m) and pertussis toxin (1 ng/ml). This inhibition is overcome by addition of arachidonic acid or hypotonic cell-free eluate that contains hepoxilin A3; (v) NaF, 1 mm, induces hepoxilin A3 formation, tested by the RVD reconstitution assay; and (vii) GDP
S inhibits hepoxilin A3 formation associated with flow. Therefore, it seems that G proteins are involved in the initial step of the mechanical-biochemical transduction leading to hepoxilin A3 formation in human platelets.DeceasedThis work is dedicated to the memory of Prof. A.A. Livne. It was carried out at the Amelia (Mimi) Rose Laboratory for Cellular Signal Transduction at the Department of Life Sciences, Ben-Gurion University of the Negev. We thank A. Dannon for helpful discussion. 相似文献
12.
Filippovich S. Yu. Rybakov Yu. A. Afanasieva T. P. Bachurina G. P. Lukina G. P. Ezhova I. E. Nosova A. V. Artjushkina T. V. Sineokii S. P. Kritskii M. S. 《Applied Biochemistry and Microbiology》2001,37(5):473-479
The specific activity of lipoxygenase from several strains of the zygomycete Mortierellavaried from 1.02 to 2.02 mol diene per min per mg protein. The enzyme equally used linoleic or arachidonic acid as a substrate. An increase in lipoxygenase activity was observed after adding corn oil to the culture medium. Tests with inhibitors having different chemical structures revealed that the lipoxygenase activity from Mortierellacells was inhibited only by esculetin, ethanol, and nordihydroguaiaretic acid (NDGA). NDGA inhibited the enzyme in vitro(IC50=142 M), but its addition in the exponential phase of growth activated the enzyme. 相似文献
13.
The phospholipid requirement for Ca2+-stimulated, Mg2+-dependent ATP hydrolysis (Ca2+/Mg2+-ATPase) and Mg2+-stimulated ATP hydrolysis (Mg2+-ATPase) in rat brain synaptosomal membranes was studied employing partial delipidation of the membranes with phospholipase A2 (Hog pancreas), phospholipase C (Bacillus cereus) and phospholipase D (cabbage). Treatment with phospholipase A2 caused an increase in the activities of both Ca2+/Mg2+-ATPase and Mg2+-ATPase whereas with phospholipase C treatment both the enzyme activities were inhibited. Phospholipase D treatment had no effect on Ca2+/Mg2+-ATPase but Mg2+-ATPase activity was inhibited. Inhibition of Mg2+-ATPase activity after phospholipase C treatment was relieved with the addition of phosphatidylinositol-4,5-bisphosphate (PIP2) and to a lesser extent with phosphatidylinositol-4-phosphate (PIP) and phosphatidylcholine (PC). Phosphatidylserine (PS), phosphatidic acid (PA), PIP and PIP2 brought about the reactivation of Ca2+/Mg2+-ATPase. Phosphatidylinositol (PI) and PA inhibited Mg2+-ATPase activity.K
ms for Ca2+ (0.47 M) and Mg2+ (60 M) of the enzyme were found to be unaffected after treatment with the phospholipases. 相似文献
14.
S. F. Perry 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1990,159(6):761-769
Summary The respiratory surface area (SAR) per kilogram body mass (MB), the harmonic mean thickness of the air-blood barrier (htR) in the gas exchange tissue, and the anatomical diffusion factor (ADF=SAR/htR per MB) were calculated for four juvenile Nile crocodiles. The ADF of three small specimens (mean MB=3.59 kg) was 625 cm2·m–1·kg–1. The values varied considerably among individuals and were similar to that of a 5.68-kg specimen (593 cm2·m–1·kg–1). Only 9% of the ADF is located in the anterior third of the lung, which because of its conical shape makes up only 14 percent of the total lung volume. Particularly in the middle third of the lung, the proximal region near the intrapulmonary bronchus displays a greater ratio of respiratory/non-respiratory surface areas than do more distally located sampling sites. The htR is also significantly smaller proximally than distally. The cumulative ADF per unit MB is greater than that previously reported for this species on the basis of overall estimates of SAR and htR, but is still less than that of lizards and testudinids. The disposition of ADF between distal air storage region and the intrapulmonary bronchus is consistent with a bidirectional cross-current gas exchange model.Abbreviations
ADF
anatomical diffusion factor
- %AR
percent of SA included in the effective respiratory zone
-
M
B
body mass
-
NVP
non-ventilatory period
- %P
percent of total lung volume containing parenchyma
-
S
A
total surface area of intrapulmonary septa
-
S
ANR
that portion ofS
A
lying out the effective respiratory zone
-
S
V
surface-to-volume ratio in the parenchyma
- htR
harmonic mean thickness of the air-blood tissue barrier within the respiratory zone
-
V
P
parenchymal volume
-
VP
ventilatory period 相似文献
15.
N. Stevnsborg H. G. Lawford N. Martin T. Beveridge 《Applied microbiology and biotechnology》1986,25(2):116-123
Summary Increasing the temperature in chemostat culture ofZymomonas mobilis ATCC 29 191 with low and high glucose concentrations was found to result in a decreasing frequency of septation leading to the formation of long filaments and in increasing outer membrane blebbing. Whether this effect is strain specific or universal inZymomonas is, unknown. Improvements in the fermentation kinetics could be achieved at elevated temperatures, with an optimum at 33°C. Temperatures >30°C induced uncoupled growth in chemostat cultures ofZ. mobilis ATCC 29 191. The results of this study emphasize the importance of temperature regulation in optimizing the performance of continuous fermentations withZymomonas.Nomenclature
D
Dilution rate, 1/h
- max
Maximum specific growth rate, 1/h
-
S
R
Initial substrate concentration, g glucose/1
- S
Amount of glucose consumed, g glucose/1
-
S
0
Effluent substrate concentration, g glucose/1
-
X
Biomass concentration
- g
cells/1
- [P]
Amount of product formed, g ethanol/1
- [P]
Product concentrations, g ethanol/l
-
Y
x/s
Growth yield, g cells/g glucose used
-
Y
p/s
Product yield, g ethanol/g glucose used
-
O
s
Specific rate of glucose uptake, g glucose/g cells/h
-
Q
p
Specific rate of ethanol formation, g ethanol/g cells/h
-
VP
Volumetric productivity, g ethanol/1/h
-
t
Fermentation time, h
Corresponding author 相似文献
16.
Gerd Wallukat Gyorgy Nemecz Tibor Farkas Hartmut Kuehn Albert Wollenberger 《Molecular and cellular biochemistry》1991,102(1):35-47
Incubation of rocker-cultured neonatal rat heart cells with 3 mM L(+)-lactate led to a sharp increase in the sensitivity of cardiomyocytes to the beta-adrenergic agonist isoprenaline, as measured by their chronotropic response. This effect was accompanied by a reduction in the arachidonic acid content of the total phospholipids. The phospholipase A2-activator melittin as well as free arachidonic acid induced this supersensitivity to the same degree. On the other hand, the L(+)-lactate-evoked supersensitivity could be blocked by the phospholipase A2 inhibitors mepacrine and n-bromophenacyl-bromide, suggesting an involvement of phospholipase A2 in the process of beta-adrenergic sensitization. The sensitizing action of arachidonic acid was blocked by the lipoxygenase inhibitors esculetin and nordihydroguaiaretic acid, but not by the cyclooxygenase inhibitor indomethacin. Supersensitivity was likewise evoked by 15-S-hydroxyeicosatetraenoic acid (15-S-HETE), but not by 5-S-HPETE or 5-S-HETE. These findings suggest that the phospholipase A2-15-lipoxygenase pathway plays a role in the induction of beta-adrenergic supersensitivity in the cultured cardiomyocytes and point to a new physiological role of the lipoxygenase product 15-S-HETE.Abbreviations NDGA
nordihydroguaiaretic acid
- HETE
hydroeicosatetraenoic acid
- HPETE
hydroperoxyeicosatetraenoic acid 相似文献
17.
The rat major histocompatibility complex (RT1-B region) codes for two sets of class II molecules (la antigens) referred to as A and E. Each class II molecule is composed of two glycoprotein chains called the A
and A
or E
and E
. Two cDNA clones encoding rat A
chains were identified from cDNA derived from rat spleen mRNA using a combination of mRNA selection and colony hybridization techniques. The complete nucleotide sequence of the cDNA insert of one of these cDNA clones, pRIa.2, was determined. This sequence codes for the carboxy-terminal 129 amino acids of the rat A
chain and 293 nucleotides of 3 untranslated sequence. The rat A
chain was shown to be highly homologous in terms of both protein and DNA sequence identities to HLA-DC and H-2 A
chains. Comparison between the coding regions of the cDNA insert of pRla.2 and the corresponding region of a cDNA insert encoding an HLA-DC1 chain showed sequence identities of 85% and 81% at the protein and DNA levels, respectively. Comparison between pRIa.2 and cDNA encoding an H-2 A
chain sequence showed identities of 91% for both protein and DNA. Results are discussed which strongly suggest that the class II A and E primordial genes arose by gene duplication prior to the evolutionary divergence of the mammals. 相似文献
18.
The GABAA Receptor Complex as a Target for Fluoxetine Action 总被引:3,自引:0,他引:3
Tunnicliff G. Schindler N. L. Crites G. J. Goldenberg R. Yochum A. Malatynska E. 《Neurochemical research》1999,24(10):1271-1276
The clinically important antidepressant fluoxetine is established as a selective serotonin reuptake inhibitor. This study demonstrates that fluoxetine also interacts with the GABAA receptor complex. At concentrations above 10 M fluoxetine inhibited the binding of both [3H]GABA (IC50 = 2 mM) and [3H]flunitrazepam (IC50 = 132 M ) to the GABAA receptor complex in brain cortical membranes. Low fluoxetine concentrations (1 nM) enhanced GABA-stimulated Cl– uptake by a rat cerebral cortical vesicular preparation. At higher concentrations (100 M and 1 mM), however, fluoxetine inhibited GABA-stimulated Cl– uptake, an effect related to a reduction in Emax. These observations might assist in an explanation of the basis of the antidepressant action of fluoxetine. 相似文献
19.
《The International journal of biochemistry》1992,24(11):1691-1695
- 1.1. Regulatory properties of lipoxygenase activity in rat brain cytosol were studied using linoleic acid (LA) as a substrate.
- 2.2. A change in the absorbance at 234 nm was biphasic when a mixture of LA and pre-formed hydroperoxide (LA-OOH) was incubated with freshly isolated native brain cytosol. Initially, a rapid depletion of LA-OOH was observed with a concomitant formation of LA-oxo compounds. This phase was followed by LA dioxygenation.
- 3.3. Both hydroperoxidase and dioxygenase activities of lipoxygenase were inhibited by micromolar concentrations of classic lipoxygenase inhibitors (phenidone, 5,8,11-eicosatriynoic acid and nordihydroguaiaretic acid).
- 4.4. The dioxygenase activity in dialysed cytsool was stimulated by nanomolar concentrations of H2O2 and micromolar concentrations of LA-OOH and it was inhibited by serotonin, dopamine and norepinephrine (IC50 25–43 μM).
20.
When growth-phase cell suspension cultures of Scutellaria baicalensis were treated with 50 g of yeast elicitor preparation ml–1, both oleanolic acid and ursolic acid transiently increased in the culture medium rather than in the cells. The maximal triterpenoid concentration was 13.7 mg l–1 media approx. 35 h after treatment, whereas the maximum concentration was 2.1 mg l–1 media after about 20 h following treatment with methyl jasmonate. Elicitor treatment also doubled phospholipase A2 activity (25 pmol mg–1 min) and the simultaneous treatment of aristolochic acid, a phospholipase A2 inhibitor, inhibited triterpenoids accumulation as well as phospholipase A2 activity. 相似文献