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1.
Platelet-activating factor-induced aggregation of human platelets specifically inhibited by triazolobenzodiazepines 总被引：6，自引：0，他引：6
Platelet-activating factor (PAF), a naturally occurring phospholipid, is a potent activator of various biological processes, including platelet aggregation. The mechanisms by which PAF acts are largely unknown, partly because of the lack of specific inhibitors for PAF-elicited responses. It was found that in washed human platelets the psychotropic triazolobenzodiazepine drugs alprazolam and triazolam potently inhibited PAF-induced changes in shape, aggregation, and secretion. The effects were specific for PAF activation, since the responses of human platelets to adenosine diphosphate, thrombin, epinephrine, collagen, arachidonate, and the calcium ionophore A23187 were not inhibited by the triazolobenzodiazepines. These psychotropic drugs should be useful in investigating the possibility that PAF or PAF-like phospholipids play a role in neuronal function and in elucidating biochemical mechanisms activated specifically by PAF in a variety of cells. 相似文献
2.
Healthy newborn Simmental and Black Pied calves with a normal number of platelets in bloodstream don’t have reliable dynamics
of the aggregation function of blood platelets with adenosine diphosphate, collagen, thrombin, ristocetin, epinephrine, as
well as combinations of ADP + epinephrine, ADP + collagen, and collagen + epinephrine inducers. The level of discocytes in
blood on days 1–2 was 78.5, not reliably changing until the end of the neonatal stage. In this case, the number of disco-echinocytes,
spherocytes, spheroechinocytes, and bipolar forms of platelets in the bloodstream remained stably low. Maintenance during
colostrum feeding of a low intensity of metabolism of endogenous arachidonic acid in platelets and of a low content of ATP,
ADP, actin, and myosin in them can be considered important mechanisms providing stability of platelet aggregation activity
in calves in the neonatal stage. 相似文献
3.
S P Saxena L J Brandes A B Becker K J Simons F S LaBella J M Gerrard 《Science (New York, N.Y.)》1989,243(4898):1596-1599
Inhibition of human platelet aggregation by N,N-diethyl-2-[4-(phenylmethyl)phenoxy]ethanamine-HCl (DPPE), a novel antagonist of histamine binding, suggested that histamine might serve a critical role in cell function. Phorbol-12-myristate-13-acetate (PMA) or collagen was found to increase platelet histamine content in parallel with promotion of aggregation. Inhibitors of histidine decarboxylase (HDC) suppressed both aggregation and the elevation of histamine content, whereas DPPE inhibited aggregation only. In saponin-permeabilized platelets, added histamine reversed the inhibition by DPPE or HDC inhibitors on aggregation induced by PMA or collagen. The results indicate a role for histamine as an intracellular messenger, which in platelets promotes aggregation. 相似文献
4.
Actinomycin D: inhibition of respiration and glycolysis 总被引：21，自引：0，他引：21
Actinomycin D inhibited respiration and anaerobic glycolysis of human leukemic leukocytes and lowered the adenosine triphosphate content of the cells. Inhibitory effects on respiration and on RNA synthesis could not be dissociated from one another over a wide range of drug concentrations. Actinomycin D also impaired protein synthesis, probably by decreasing the availability of adenosine triphosphate and by inhibiting messenger RNA. 相似文献
5.
Inhibition of platelet aggregation by monoclonal antibody reactive with beta 2-microglobulin chain of HLA complex 总被引：1，自引：0，他引：1
A mouse monoclonal antibody that reacts with beta 2-microglobulin, the light chain of class I major histocompatibility antigens, inhibited the second wave of human platelet aggregation induced by adenosine diphosphate and epinephrine and blocked aggregation and platelet protein phosphorylation induced by sodium arachidonate. Thrombin-induced platelet aggregation was inhibited at threshold concentrations but not at higher concentrations. The antibody also inhibited aggregation and secretion in response to thromboxane A2 or the stable endoperoxide analog, U46619. These results suggest that beta 2-microglobulin in the histocompatibility complex is intimately associated with transmission of the endoperoxide-thromboxane signal at the platelet membrane. 相似文献
6.
临床上大部分抗血小板药物存在继发性出血等副作用,亟需寻找一种安全有效的抗血小板药物。二磷酸腺苷(ADP)和花生四烯酸(AA)是介导血小板聚集的主要物质,文章探讨成纤维细胞生长因子-21(FGF-21)是否抑制ADP或AA诱导大鼠血小板聚集和活化。将大鼠分为正常对照组、正常鼠血小板活化组、阿司匹林干预后血小板活化组、FGF-21高、中、低剂量干预后血小板活化组。给药干预后提取各组血小板,分别用ADP或AA处理,观察处理后血小板聚集情况以及P选择素和血栓素(TXB2)表达水平。与正常对照组相比,正常鼠血小板经ADP或AA处理活化后,血小板聚集率显著升高,血浆中P选择素和TXB2含量明显上升;与正常鼠血小板经ADP或AA处理活化后相比,经阿司匹林和FGF-21干预后分别经ADP或AA处理活化后的血小板聚集率显著下降,血浆中P选择素和TXB2含量显著下降;FGF-21干预组经ADP或AA活化后,血小板聚集率、P选择素和TXB2含量下降水平呈明显剂量依赖性。目前国内外尚未发现FGF-21对血小板聚集与活化作用的相关报道,研究首次证明FGF-21具有抑制ADP和AA诱导血小板聚集和活化作用及明显的抗血凝作用,填补FGF-21在抗血凝研究领域空白,为开发安全有效的抗血凝药物提供理论依据。 相似文献
7.
Biosynthesis of biopterin: adrenergic cyclic adenosine monophosphate-dependent inhibition in the pineal gland 总被引：6，自引：0，他引：6
Pineal glands in organ culture synthesize and release biopterin and are able to maintain concentrations of biopterin occurring in vivo for up to 54 hours in vitro. The intracellular biopterin content is reduced 50 percent by treatment with l-norepinephrine or cyclic adenosine monophosphate derivatives, but not by d-norepinephrine. This is an indication that biopterin levels are regulated by an adrenergic cyclic adenosine monophosphate-dependent mechanism. The decline in tissue biopterin content, produced mainly by inhibited of biosynthesis, is maximal at 6 hours and is not associated with either an increase in biopterin release or a shift in the reduction state of the biopterin. 相似文献
8.
Alonso MC Drummond DR Kain S Hoeng J Amos L Cross RA 《Science (New York, N.Y.)》2007,316(5821):120-123
Kinesin-1 is a two-headed molecular motor that walks along microtubules, with each step gated by adenosine triphosphate (ATP) binding. Existing models for the gating mechanism propose a role for the microtubule lattice. We show that unpolymerized tubulin binds to kinesin-1, causing tubulin-activated release of adenosine diphosphate (ADP). With no added nucleotide, each kinesin-1 dimer binds one tubulin heterodimer. In adenylyl-imidodiphosphate (AMP-PNP), a nonhydrolyzable ATP analog, each kinesin-1 dimer binds two tubulin heterodimers. The data reveal an ATP gate that operates independently of the microtubule lattice, by ATP-dependent release of a steric or allosteric block on the tubulin binding site of the tethered kinesin-ADP head. 相似文献
9.
V Bertelé A Falanga M Tomasiak E Dejana C Cerletti G de Gaetano 《Science (New York, N.Y.)》1983,220(4596):517-519
Selective pharmacological inhibition of thromboxane A2 synthesis did not prevent arachidonate-induced aggregation of human platelets in vitro. Prevention was instead achieved by a combination of thromboxane A2 inhibitors with low concentrations of aspirin. The latter partially reduced the proaggregatory cyclooxygenase products that accumulated when thromboxane A2 synthesis was blocked. The aspirin concentrations did not affect per se either platelet aggregation or prostacyclin synthesis in cultured human endothelial cells. The combination of thromboxane synthetase inhibitors with low doses of aspirin may offer greater antithrombotic potential than either drug alone. 相似文献
10.
Starch-deficient maize mutant lacking adenosine dephosphate glucose pyrophosphorylase activity 总被引：24，自引：0，他引：24
The maize mutant shrunken-2 synthesizes only 25 to 30 percent as much starch as normal maize; it completely lacks adenosine diphosphate glucose pyrophosphorylase activity in both endosperm and embryo tissue. Identification of the mutant block indicates that the greater portion of starch in the endosperm of normal maize is synthesized by way of enzyme systems that utilize adenosine diphosphate glucose as a substrate, and that the latter is formed chiefly by adenosine diphosphate glucose pyrophosphorylase. 相似文献
11.
Hsp70 of the mitochondrial matrix (mtHsp70) provides a critical driving force for the import of proteins into mitochondria. Tim44, a peripheral inner-membrane protein, tethers it to the import channel. Here, regulated interactions were found to maximize occupancy of the active, adenosine 5'-triphosphate (ATP)-bound mtHsp70 at the channel through its intrinsic high affinity for Tim44, as well as through release of adenosine diphosphate (ADP)-bound mtHsp70 from Tim44 by the cofactor Mge1. A model peptide substrate rapidly released mtHsp70 from Tim44, even in the absence of ATP hydrolysis. In vivo, the analogous interaction of translocating polypeptide would release mtHsp70 from the channel. Consistent with the ratchet model of translocation, subsequent hydrolysis of ATP would trap the polypeptide, driving import by preventing its movement back toward the cytosol. 相似文献
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14.
Dimethyl sulfoxide prevented loss of respiratory control and decrease in efficiency of oxidative phosphorylation when plant mitochondria were stored in liquid nitrogen. Respiration was severely inhibited and was not stimulated by adenosine diphosphate when mitochondria were frozen in liquid nitrogen without dimethyl sulfoxide. Thus, isolated mitochondria provide a model system for the study of the effects of freezing on biological membranes and of the prevention, by dimethyl sulfoxide, of freezing damage. 相似文献
15.
Mitochondria from healthy oat seedlings oxidized succinate with good respiratory control and high ratios of adenosine diphosphate to oxygen. After treatment with victorin, the pathotoxin responsible for symptoms of Victoria blight of oats, susceptible seedlings yielded mitochondria with little respiratory control and lower ratios of adenosine diphosphate to oxygen. No such effects were obtained with victorin-treated resistant seedlings or when victorin was added directly to mitochondria from healthy susceptible or resistant plants. These data indicate that victorin-induced disease results in a reduction in efficiency of the energy-generating system of isolated mitochondria. 相似文献
16.
Relation between work and phosphate metabolite in the in vivo paced mammalian heart 总被引：16，自引：0，他引：16
Nuclear magnetic resonance (NMR) spectroscopy was used to monitor, on a beat-to-beat basis, the concentration of creatine phosphate and adenosine triphosphate during alterations in the work output of canine hearts in vivo. Over a wide range of rate-pressure products (5,000 to 25,000 mmHg/min), the relative amounts of creatine phosphate and adenosine triphosphate within the heart remained constant. The relative concentration of free adenosine diphosphate was calculated under the reasonable assumption that the creatine kinase-catalyzed reaction is near equilibrium in this tissue. The free concentration of adenosine diphosphate also did not change over this range of rate-pressure products. The data demonstrate that the concentration of these compounds is highly regulated in vivo and suggest that factors other than their concentration may be involved in the modulation of steady-state myocardial work output with oxygen consumption. 相似文献
17.
E. N. Soboleva 《Russian Agricultural Sciences》2018,44(5):474-476
The objective of the work was to study the effects of hirudotherapy on the hemostasis plasma link in cows with clinical mastitis. The blood test for 20 lactating Ayrshire cows was performed. The most active aggregation after hirudotherapy was recorded for the collagen-induced aggregation. Platelet disaggregation capabilities decreased with the impacts of adenosine diphosphate (ADP) and ristomycin. A significant decrease in the activated partial thromboplastin time (APTT) (P ≤ 0.01), the prothrombin time (PTT) (P ≤ 0.01), and the thrombin time (TT) was revealed. The use of medical leeches in the treatment of the clinical bovine mastitis did not prove any significant effect on the adhesive-aggregation activity of platelets. However, it had a corrective effect on the plasma-coagulation link of hemostasis. 相似文献
18.
Hormonal control of neutrophil lysosomal enzyme release: effect of epinephrine on adenosine 3',5'-monophosphate 总被引：3，自引：0，他引：3
Human neutrophilic leukocytes release neutral protease and beta-glucuronidase during cell contact with, and phagocytosis of, zymosan particles treated with rheumatoid arthritic serum. Release of lysosomal enzymes is inhibited by epinephrine and adenosine 3',5'-monophosphate (cyclic AMP), but not by phenylephrine or adenosine 5'-monophosphate. Inhibition of enzyme release by epinephrine may be mediated by cyclic AMP because the cyclic AMP in the neutrophils is increased by epinephrine treatment at the time when enzyme release is reduced. 相似文献
19.
The isolated taenia coli of the guinea pig takes up tritiated adenosine, adenosine monophosphate, adenosine diphosphate, and adenosine triphosphate, in preference to tritiated inosine and adenine. After uptake, [(3)H]adenosine is converted and retained primarily as [(3)H]adenosine triphosphate. Tritium is released from taenia coli treated with [(3)H]adenosine upon activation of the nonadrenergic inhibitory nerves. These results are consistent with the previous evidence that adenosine triphosphate may be the transmitter from the nerves. 相似文献
20.
Phosphorylation coupled to the transfer of electrons from glutathione to cytochrome c 总被引：1，自引：0，他引：1
Formation of adenosine diphosphate from adenosine monophosphate and inorganic phosphate can be coupled to the oxidation of reduced glutathione by cytochrome c in a reaction which requires oxidized glutathione as a catalyst. The reaction occurs with purified materials in tris(hydroxymethyl)aminomethane buffer and may represent the type reaction for one or more oxidative phosphorylations. 相似文献