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1.
The involvement of metabolic energy in platelet responses was investigated by measuring the energy consumption during aggregation and secretion from dense, alpha- and acid-hydrolase-containing granules. Gel-filtered human platelets were stimulated with different amounts of thrombin (0.05-5.0 units X ml-1). At various stages during aggregation and secretion the energy consumption was measured from the changes in metabolic ATP and ADP following abrupt arrest of ATP resynthesis. Stimulation with 5 units of thrombin X ml-1 increased the energy consumption from 6.2 +/- 0.9 to 17.8 +/- 0.4 mumol of ATPeq. X min-1 X (10(11) platelets)-1 during the first 15 s. It decreased thereafter and returned to values found in resting cells after about 30 s. With 0.05 unit of thrombin X ml-1, the energy consumption accelerated more slowly and took at least 3 min before it normalized. A strong positive correlation was found between the velocities of the three secretion responses and the concurrent energy consumption (a) at different stages of the responses induced by a given dose of thrombin, and (b) at different secretion velocities initiated by different amounts of thrombin. When, at different stages of the responses, the extent of secretion was compared with the amount of energy that had been consumed, a strong linear correlation was found with the increment in energy consumption but not with the total energy consumption. This correlation was independent of the concentration of thrombin and indicated that complete secretion from dense, alpha- and acid-hydrolase-containing granules was paralleled by an increment of 4.0, 6.5 and 6.7 mumol of ATPeq. X (10(11) platelets)-1, respectively. An energy cost of 0.7 mumol of ATPeq. X (10(11) platelets)-1 was calculated for separate dense-granule secretion, whereas the combined alpha- and acid-hydrolase granule secretion required 5.3 mumol of ATPeq. X (10(11) platelets)-1. There was no correlation between energy consumption and optical aggregation. In contrast, the rate of single platelet disappearance, which is a measure for the early formation of small aggregates, correlated closely with the rate of energy consumption. Compared with secretion, however, the energy requirement of single platelet disappearance was minor, since 2mM-EDTA completely prevented this response but decreased the energy consumption only slightly. An increase of 0.5-1.0 mumol of ATPeq. X (10(11) platelets)-1 was seen before single platelet disappearance and the three secretion responses were initiated, indicating an increase in energy consuming processes that preceded these responses.(ABSTRACT TRUNCATED AT 400 WORDS) 相似文献
2.
The energetics of early platelet responses. Energy consumption during shape change and aggregation with special reference to protein phosphorylation and the polyphosphoinositide cycle. 总被引:3,自引:3,他引:0
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Among the different platelet responses, secretion requires the greatest amount of metabolic energy. The velocities of dense, alpha- and acid hydrolase granule secretion vary in parallel with the increase in energy consumption seen in thrombin-stimulated cells. This covariance is preceded by a phase in which energy consumption is increased without the extracellular appearance of secretion markers. By treating the platelets with thrombin and hirudin we have stimulated the platelets for short intervals and succeeded in separating shape change, single platelet disappearance and secretion to a great extent. In this report we show that the early increase in energy consumption reflects the energy requirement of aggregation but not of shape change. The cost of 100% of single platelet disappearance is 2.8 mumol of ATPeq. X (10(11) platelets)-1. Concurrent analysis of phosphorylation of Mr 20 000 and 47 000 proteins and of 32P-labelled phosphatidylinositol metabolites led to the following observations. Firstly, shape change is neither accompanied by an increase in protein phosphorylation nor by changes in the steady state levels of 32P-labelled phosphatidylinositol metabolites. Secondly, when aggregation occurs both proteins are phosphorylated, but the phosphatidylinositol metabolites do not change. Thirdly, when secretion follows, more phosphorylation of the Mr 47 000 protein occurs and initially only phosphatidic acid accumulates. At a later stage of the secretion responses, more protein phosphorylation and phosphatidic acid accumulation become evident, and are now accompanied by alterations in the steady state levels of 32P-labelled (poly)phosphoinositides. Hence, the early increase in energy consumption coincides with protein phosphorylation and, at a later stage, with alterations in (poly)phosphoinositides metabolites. This demonstrates that metabolic energy is directly involved in stimulus-response coupling in aggregating platelets. 相似文献
3.
Robert Goggs Matthew T. Harper Robert J. Pope Joshua S. Savage Christopher M. Williams Stuart J. Mundell Kate J. Heesom Mark Bass Harry Mellor Alastair W. Poole 《The Journal of biological chemistry》2013,288(47):34217-34229
Rho GTPases such as Rac, RhoA, and Cdc42 are vital for normal platelet function, but the role of RhoG in platelets has not been studied. In other cells, RhoG orchestrates processes integral to platelet function, including actin cytoskeletal rearrangement and membrane trafficking. We therefore hypothesized that RhoG would play a critical role in platelets. Here, we show that RhoG is expressed in human and mouse platelets and is activated by both collagen-related peptide (CRP) and thrombin stimulation. We used RhoG−/− mice to study the function of RhoG in platelets. Integrin activation and aggregation were reduced in RhoG−/− platelets stimulated by CRP, but responses to thrombin were normal. The central defect in RhoG−/− platelets was reduced secretion from α-granules, dense granules, and lysosomes following CRP stimulation. The integrin activation and aggregation defects could be rescued by ADP co-stimulation, indicating that they are a consequence of diminished dense granule secretion. Defective dense granule secretion in RhoG−/− platelets limited recruitment of additional platelets to growing thrombi in flowing blood in vitro and translated into reduced thrombus formation in vivo. Interestingly, tail bleeding times were normal in RhoG−/− mice, suggesting that the functions of RhoG in platelets are particularly relevant to thrombotic disorders. 相似文献
4.
Franoise Marcenac Denis Blache 《Biochimica et Biophysica Acta (BBA)/General Subjects》1985,840(3):377-382
Differential pulse voltammetry combined with electrochemically treated carbon fibre microelectrodes was used to monitor endogenous serotonin release occurring during platelet aggreagtion. After platelet stimulation by thrombin, an oxidation peak was recorded at +280 mV. HPLC analyses performed with fluorimetric detection have shwon that this released electroactive compound was essentially serotonin. Moreover, serotonin measurements in the same samples by the technique reported here and by fluorimetry were found to be very similar (1.15 ± 0.30 μM and 1.17 ± 0.15 μM (mean ± dS.D., n = 6), respectively). Extracellular serotonin concentrations could be estimated either directly during aggregation or in supernatants obtained from stimulated or lysed platelets. Maximal serotonin concentrations have been found to be 6.93 ± 0.37 and 3.28 ± 0.39 nmol/109 platelets from rat and human, respectively. Using the reported procedure, we have observed that no serotonin was released from thrombin-stimulated platelets prepared from rats treated with reserpine. Our new technique represents a selective and performant tool for rapid determination of endogenous serotonin platelet secretion. 相似文献
5.
M. Elisa Lopes-Pires Ana C. Antunes Naime Nádia J. Almeida Cardelli Débora J. Anjos Edson Antunes Sisi Marcondes 《PloS one》2015,10(9)
Sepsis severity has been positively correlated with platelet dysfunction, which may be due to elevations in nitric oxide (NO) and cGMP levels. Protein kinase C, Src kinases, PI3K and AKT modulate platelet activity in physiological conditions, but no studies evaluated the role of these enzymes in platelet aggregation in sepsis. In the present study we tested the hypothesis that in sepsis these enzymes positively modulate upstream the NO-cGMP pathway resulting in platelet inhibition. Rats were injected with lipopolysaccharide (LPS, 1 mg/kg, i.p.) and blood was collected after 6 h. Platelet aggregation was induced by ADP (10 μM). Western blotting assays were carried out to analyze c-Src and AKT activation in platelets. Intraplatelet cGMP levels were determined by enzyme immunoassay kit. Phosphorylation of c-SRC at Tyr416 was the same magnitude in platelets of control and LPS group. Incubation of the non-selective Src inhibitor PP2 (10 μM) had no effect on platelet aggregation of LPS-treated rats. LPS increased intraplatelet cGMP levels by 5-fold compared with control group, which was accompanied by 76% of reduction in ADP-induced platelet aggregation. The guanylyl cyclase inhibitor ODQ (25 μM) and the PKG inhibitor Rp-8-Br-PET-cGMPS (25 μM) fully reversed the inhibitory effect of LPS on platelet aggregation. Likewise, the PKC inhibitor GF109203X (10 μM) reversed the inhibition by LPS of platelet aggregation and decreased cGMP levels in platelets. AKT phosphorylation at Thr308 was significantly higher in platelets of LPS compared with control group, which was not reduced by PI3K inhibition. The AKT inhibitor API-1 (20 μM) significantly increased aggregation and reduced cGMP levels in platelets of LPS group. However, the PI3K inhibitor wortmannin and LY29004 had no effect on platelet aggregation of LPS-treated rats. Therefore, inhibition of ADP-induced platelet aggregation after LPS injection is mediated by cGMP/PKG-dependent mechanisms, and PKC and AKT act upstream upregulating this pathway. 相似文献
6.
M.H. Fukami H. Holmsen L. Salganicoff 《Biochimica et Biophysica Acta (BBA)/General Subjects》1976,444(3)
Changes in the energy metabolism of washed human platelets were compared with the kinetics of secretion induced by thrombin (5 units/ml). A 50% decrease in the level of metabolic ATP (3H-labelled), which was essentially complete in 30 s, was matched in rate by adenine nucleotide secretion from storage in dense granules. Incubation of platelets with antimycin before thrombin addition increased the rate of fall in metabolic ATP, but did not affect the rate of adenine nucleotide secretion. β-N-Acetylglucosaminidase secretion, which was slower than adenine nucleotide secretion in control platelets, was noticeably inhibited by antimycin, confirming previous reports that different regulatory mechanisms exist for dense and α-granule secretion. The rates of rephosphorylation of metabolic ADP to ATP via glycolysis and oxidative phosphorylation were estimated by measuring lactate production and O2 consumption in resting and thrombin-stimulated platelets and compared to the level of metabolic ATP (9–10 nmol/mg of platelet protein in the resting state). The rate of ATP production was stimulated at least two fold from 12 nmol to 24 nmol/min/mg within seconds of thrombin addition. This increased rate was maintained over the observed period of 5 min although the level of metabolic ATP had decreased to 4–5 nmol/mg within 30 s; the turnover of the remaining metabolic ATP thus increased four fold over the resting state although the actual stimulation of energy production was only two fold. 相似文献
7.
Comparative studies on the energetics of platelet responses induced by different agonists. 总被引:2,自引:1,他引:1
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The correlation between energy consumption and platelet responses induced by collagen, A23187 and ADP was investigated and compared with the energetics of thrombin-stimulated platelets established in earlier work. Aggregation, measured as single-platelet disappearance, and secretion correlated quantitatively with the increment but not with the total consumption of energy, suggesting that the former reflects the energy cost of these responses. The cost of complete aggregation was 2-3 mumol of ATP equivalents/10(11) platelets with collagen, ADP and thrombin as the stimulus. The cost of complete dense-granule secretion was 0.5-0.8 mumol of ATP equivalents/10(11) platelets with all agonists tested. The cost of combined secretion of alpha-granule and acid hydrolase granule contents was 5-7 mumol of ATP equivalents/10(11) platelets with thrombin and collagen. However, in the presence of A23187 much more energy was consumed during aggregation and secretion. Also ADP triggered more energy consumption during secretion than was seen with the other inducers. The effect of inhibitors of aggregation and secretion was investigated in thrombin-stimulated platelets. Raising the cellular cyclic AMP content sharply decreased the increment in energy consumption as well as aggregation and secretion. The cytoskeleton-disrupting agents cytochalasin B and colchicine left the increment in energy consumption intact, but decreased the basal consumption seen in unstimulated platelets. This was accompanied by normal (cytochalasin B) or diminished (colchicine) aggregation and secretion. Apart from the latter exception, all inhibitors decreased secretion and incremental energy consumption in parallel, thereby preserving the energy-versus-secretion relationship established in earlier work. In contrast, aggregation and energy consumption varied independently, suggesting that the coupling with energy consumption is much weaker for this response. 相似文献
8.
Soochong Kim Carol Dangelmaier Dheeraj Bhavanasi Shu Meng Hong Wang Lawrence E. Goldfinger Satya P. Kunapuli 《The Journal of biological chemistry》2013,288(47):34230-34238
We investigated the mechanism of activation and functional role of a hitherto uncharacterized signaling molecule, RhoG, in platelets. We demonstrate for the first time the expression and activation of RhoG in platelets. Platelet aggregation, integrin αIIbβ3 activation, and α-granule and dense granule secretion in response to the glycoprotein VI (GPVI) agonists collagen-related peptide (CRP) and convulxin were significantly inhibited in RhoG-deficient platelets. In contrast, 2-MeSADP- and AYPGKF-induced platelet aggregation and secretion were minimally affected in RhoG-deficient platelets, indicating that the function of RhoG in platelets is GPVI-specific. CRP-induced phosphorylation of Syk, Akt, and ERK, but not SFK (Src family kinase), was significantly reduced in RhoG-deficient platelets. CRP-induced RhoG activation was consistently abolished by a pan-SFK inhibitor but not by Syk or PI3K inhibitors. Interestingly, unlike CRP, platelet aggregation and Syk phosphorylation induced by fucoidan, a CLEC-2 agonist, were unaffected in RhoG-deficient platelets. Finally, RhoG−/− mice had a significant delay in time to thrombotic occlusion in cremaster arterioles compared with wild-type littermates, indicating the important in vivo functional role of RhoG in platelets. Our data demonstrate that RhoG is expressed and activated in platelets, plays an important role in GPVI-Fc receptor γ-chain complex-mediated platelet activation, and is critical for thrombus formation in vivo. 相似文献
9.
Counde O-Yang Helen Y. Wu Denis J. Kertesz Arthur F. Kluge Marshall B. Wallach Anthony L. Willis Donald L. Smith Li-Feng K. Chang 《Prostaglandins & other lipid mediators》1987,34(4)
Prostacyclin analogues derived from modification of the lower side chain of the bicyclo[3.2.0]hept-6-ylidene iminoxyacetic acid (
) were studied in inhibition of
and
platelet aggregation and in the spontaneously hypertensive rat. Iminoxyacetic acids (
) and iminoxypropionic acid
) were 2.9, 3.0, 1.9 and 2.0 times respectively more potent than PGE1 in inhibiting ADP-induced aggregation of human platelets
. Following intravenous administration at a dose of 90–110 μg/kg in the guinea pig, iminoxyacetic acids (
), (
) and iminoxypropionic acid (
) showed a maximum inhibition of 82–92% with a half life in the range of 14–22 min. Following oral administration at a dose of 1 mg/kg in the guinea pig, iminoxyacetic acids (
) and (
) inhibited heterologous platelet aggregation for 4.5 h. Following intravenous administration in spontaneously hypertensive rats, acids
)-(
) lowered the mean blood pressure in a dose dependent manner. At a dose of 100 μg/kg, the effect lasted for 20–40 min. 相似文献
10.
Javier Modrego Luis Azcona Naiara Martín-Palacios José J. Zamorano-León Antonio Segura Pablo Rodríguez Reddy Guerra Juan Tamargo Carlos Macaya Antonio J. López-Farré 《PloS one》2013,8(12)
Objective
To analyse if platelet responsiveness to aspirin (ASA) may be associated with a different ability of platelets to generate nitric oxide (NO).Patients/Methods
Platelets were obtained from 50 patients with stable coronary ischemia and were divided into ASA-sensitive (n = 26) and ASA-resistant (n = 24) using a platelet functionality test (PFA-100).Results
ASA-sensitive platelets tended to release more NO (determined as nitrite + nitrate) than ASA-resistant platelets but it did not reach statistical significance. Protein expression of nitric oxide synthase 3 (NOS3) was higher in ASA-sensitive than in ASA-resistant platelets but there were no differences in the platelet expression of nitric oxide synthase 2 (NOS2) isoform. The highest NOS3 expression in ASA-sensitive platelets was independent of the presence of T-to-C mutation at nucleotide position −786 (T−786→C) in the NOS3-coding gene. However, platelet content of phosphorylated NOS3 at Serine (Ser)1177, an active form of NOS3, was higher in ASA-sensitive than in ASA-resistant platelets. The level of platelet NOS3 Ser1177 phosphorylation was positively associated with the closure time in the PFA-100 test. In vitro, collagen failed to stimulate the aggregation of ASA-sensitive platelets, determined by lumiaggregometry, and it was associated with a significant increase (p = 0.018) of NOS3 phosphorylation at Ser1177. On the contrary, collagen stimulated the aggregation of ASA-resistant platelets but did not significantly modify the platelet content of phosphorylated NOS3 Ser1177. During collagen stimulation the release of NO from ASA-sensitive platelets was significantly enhanced but it was not modified in ASA-resistant platelets.Conclusions
Functional platelet responsiveness to ASA was associated with the platelet content of phosphorylated NOS3 at Ser1177. 相似文献11.
Spice active principles as the inhibitors of human platelet aggregation and thromboxane biosynthesis
R.H. Raghavendra K. Akhilender Naidu 《Prostaglandins, leukotrienes, and essential fatty acids》2009,81(1):73-78
Spice active principles are reported to have anti-diabetic, anti-hypercholesterolemic, antilithogenic, anti-inflammatory, anti-microbial and anti-cancer properties. In our previous report we have shown that spices and their active principles inhibit 5-lipoxygenase and also formation of leukotriene C4. In this study, we report the modulatory effect of spice active principles viz., eugenol, capsaicin, piperine, quercetin, curcumin, cinnamaldehyde and allyl sulphide on in vitro human platelet aggregation. We have demonstrated that spice active principles inhibit platelet aggregation induced by different agonists, namely ADP (50 μM), collagen (500 μg/ml), arachidonic acid (AA) (1.0 mM) and calcium ionophore A-23187 (20 μM). Spice active principles showed preferential inhibition of arachidonic acid-induced platelet aggregation compared to other agonists. Among the spice active principles tested, eugenol and capsaicin are found to be most potent inhibitors of AA-induced platelet aggregation with IC50 values of 0.5 and 14.6 μM, respectively. The order of potency of spice principles in inhibiting AA-induced platelet aggregation is eugenol>capsaicin>curcumin>cinnamaldehyde>piperine>allyl sulphide>quercetin. Eugenol is found to be 29-fold more potent than aspirin in inhibiting AA-induced human platelet aggregation. Eugenol and capsaicin inhibited thromboxane B2 (TXB2) formation in platelets in a dose-dependent manner challenged with AA apparently by the inhibition of the cyclooxygenase (COX-1). Eugenol-mediated inhibition of platelet aggregation is further confirmed by dose-dependent decrease in malondialdehyde (MDA) in platelets. Further, eugenol and capsaicin inhibited platelet aggregation induced by agonists—collagen, ADP and calcium ionophore but to a lesser degree compared to AA. These results clearly suggest that spice principles have beneficial effects in modulating human platelet aggregation. 相似文献
12.
The “in vitro” effects of α-tocopherol, butylhydroxytoluene (BHT) and butylhydroxyanisole (BHA) were studied on aggregation of human platelets induced by collagen and arachidonic acid (AA), on the metabolic conversion of 14C AA through the cyclooxygenase and lipoxygenase pathways and on the formation of thromboxane B2 (TXB2) in washed platelets after stimulation with collagen.Vitamin E completely inhibited AA induced platelet aggregation only at high concentration (mM) and after 10 minutes of preincubation, with limited effects on AA metabolism in platelets and no effect on TXB2 formation from endogenous substrate. BHA completely inhibited platelet aggregation in the 10−6M range, gave 50% inhibition of AA metabolism in the 10−5M range and almost complete inhibition of thromboxane formation in the 10−4M range. BHT was about 100 times less active on platelet aggregation and AA metabolism. The lipoxygenase and cyclooxygenase pathways were differentially affected at low concentrations of BHA and only at concentrations greater than 5×10−5M were both pathways depressed. 相似文献
13.
Sadie A. Aznavoorian M.D. Takayoshi Utsunomiya Ph.D. Michael M. Krausz M.D. Lawrence H. Cohn M.D. David Shepro Ph.D. Herbert B. Hechtman M.D. 《Prostaglandins & other lipid mediators》1983,25(4)
The antiaggregating agent prostacyclin (PGI2) was infused into ten dogs during cardiopulmonary bypass (CPB) to minimize thrombocytopenia and platelet dysfunction. The animals were anesthetized, placed on mechanical ventilation and underwent thoracotomy. After heparinization with 300 u/kg, animals were assigned to control (n=5) or PGI2 treated groups (n=5). Thoracotomy and then CPB decreased platelet numbers to below 30, 000/mm3 (p < 0.05) and fibrinogen to less than 150 mg/dl (p < 0.05). PGI2 at 100 ng/kg·min was infused for the 2 h period of CPB. PGI2 infusion did not prevent these changes, but did prevent platelet serotonin release. In the control group after CPB, platelet serotonin fell from the baseline value of 1.11 μg/109 to 0.35 μg/109 platelets (p < 0.05). In contrast, PGI2 treatment resulted in a serotonin increase to 2.27 μg/109 platelets (p < 0.05). Thromboxane B2 concentrations of platelets and plasma rose during CPB (p < 0.05). Surprisingly, PGI2 infusion accentuated this rise in platelet and plasma thromboxane B2 (p < 0.05). These data indicate that during CPB, an infusion of PGI2: 1) does not prevent thrombocytopenia; 2) increases platelet serotonin uptake despite, 3) an associated rise in platelet and plasma thromboxane B2. 相似文献
14.
Ewelina M. Golebiewska Matthew T. Harper Christopher M. Williams Joshua S. Savage Robert Goggs Gabriele Fischer von Mollard Alastair W. Poole 《The Journal of biological chemistry》2015,290(3):1536-1545
Platelet secretion not only drives thrombosis and hemostasis, but also mediates a variety of other physiological and pathological processes. The ubiquitous SNARE machinery and a number of accessory proteins have been implicated in regulating secretion in platelet. Although several platelet SNAREs have been identified, further members of the SNARE family may be needed to fine-tune platelet secretion. In this study we identified expression of the t-SNARE syntaxin 8 (STX8) (Qc SNARE) in mouse and human platelets. In mouse studies, whereas STX8 was not essential for α-granule or lysosome secretion, Stx8−/− platelets showed a significant defect in dense granule secretion in response to thrombin and CRP. This was most pronounced at intermediate concentrations of agonists. They also showed an aggregation defect that could be rescued with exogenous ADP and increased embolization in Stx8−/− mice in vivo consistent with an important autocrine and paracrine role for ADP in aggregation and thrombus stabilization. STX8 therefore specifically contributes to dense granule secretion and represents another member of a growing family of genes that play distinct roles in regulating granule release from platelets and thus platelet function in thrombosis and hemostasis. 相似文献
15.
Peng Jiang Stéphane Loyau Maria Tchitchinadze Jacques Ropers Guillaume Jondeau Martine Jandrot-Perrus 《PloS one》2015,10(6)
Exposure of platelets to collagen triggers the formation of a platelet clot. Pharmacological agents capable of inhibiting platelet activation by collagen are thus of potential therapeutic interest. Thrombus formation is initiated by the interaction of the GPIb-V-IX complex with collagen-bound vWF, while GPVI interaction with collagen triggers platelet activation that is reinforced by ADP and thromboxane A2. Losartan is an angiotensin II (Ang II) type I receptor (AT1R) antagonist proposed to have an antiplatelet activity via the inhibition of both the thromboxane A2 (TXA2) receptor (TP) and the glycoprotein VI (GPVI). Here, we characterized in vitro the effects of losartan at different doses on platelet responses: losartan inhibited platelet aggregation and secretion induced by 1 μg.mL-1 and 10 μg.mL-1 of collagen with an IC50 of ~ 6 μM. Losartan inhibited platelet responses induced by the GPVI specific collagen related peptide but not by the α2β1 specific peptide. However, losartan did not inhibit the binding of recombinant GPVI to collagen, which is not in favor of a simple competition. Indeed, the clustering of GPVI observed in flow cytometry and using the Duolink methodology, was inhibited by losartan. The impact of a therapeutic dose of losartan (100 mg/day) on platelet responses was analyzed ex vivo in a double blind study. No statistically significant differences were observed between losartan-treated (n=25) and non-treated (n=30) patients in terms of collagen and U46619-induced platelet activation. These data indicate that in treated patients, losartan does not achieve a measurable antiplatelet effect but provide the proof of concept that inhibiting collagen-induced GPVI clustering is of pharmacological interest to obtain an antithrombotic efficacy.
Trial Registration
ClinicalTrials.gov NCT00763893 相似文献16.
Don N. Harris Marie B. Phillips Inge M. Michel Harold J. Goldenberg James E. Heikes Peter W. Sprague Michael J. Antonaccio 《Prostaglandins & other lipid mediators》1981,22(2):295-307
A newly synthesized 9α-homo-9,11-epoxy-5,13-prostadienoic acid analogue, SQ 26,536, (8(R)9(S)11(R)12(S)-9α-homo-9,11-epoxy-5(Z), 13(E)-15S-hydroxyprostadienoic acid) inhibited arachidonic acid (AA)-induced platelet aggregation with an I50 value of 1.7 μ
. SQ 26,536 did not inhibit prostaglandin (PG) synthetase activity of bovine seminal vesicle microsomes or thromboxane (Tx) synthetase activity of lysed human blood platelets. SQ 26,536 also inhibited platelet aggregation induced by epinephrine (secondary phase), 9,11-azoPGH2 and collagen but did not inhibit the primary phase of epinephrine-induced aggregation or ADP-induced platelet aggregation. SQ 26,538 (8(R)9(S)11(R)12(S)-9α-homo-9-, 11-epoxy-5(Z),13(E)-15R-hydroxyprostadienoic acid), a 15-epimer of SQ 26,536, induced platelet aggregation with an A50 value of 2.5 μ
. SQ 26,536 competitively inhibited SQ 26,538-induced platelet aggregation with a Ki value of 3 μ
. Neither indomethacin, a PG synthetase inhibitor, nor SQ 80,338 (1-(3-phenyl-2-propenyl)-1H-imidazole), a Tx synthetase inhibitor, inhibited SQ 26,538- or 9,11-azoPGH2-induced platelet aggregation. These data indicate that SQ 26,536 and SQ 26,538 are stable antagonist and agonist, respectively, of the human blood platelet thromboxane receptor. 相似文献
17.
Kingsley Yin Pi-Shiang Lai Ana Rodriguez Bernd W. Spur Patrick Y. -K. Wong 《Prostaglandins & other lipid mediators》1995,50(3)
The inhibition of platelet aggregation by peroxynitrite, a reactive oxygen species derived from the interaction of nitric oxide (NO) and superoxide, was examined in platelet-rich plasma. In this report, we have used a preparation of peroxynitrite that was free of H202 and MnO2. As such, peroxynitrite dose-dependently (50–200 μA) inhibited aggregation of human platelets stimulated by ADP (5 μM), collagen (0.5 μg), thrombin (0.5 UlmL) and U46619 (1 PM). In addition, peroxynitrite reversed platelet aggregation induced by collagen, ADP, and thrombin. Peroxynitrite, preincubated with platelet-poor plasma or albumin (7%) for 30 min, did not alter the inhibition of platelet aggregation. This suggested that the inhibitory action of peroxynitrite may be due to nitrosylation of proteins, which by themselves possess activity, rather than conversion to NO or NO donors. Furthermore, we show that peroxynitrite increased the cGMP level only at 200 μM concentrations, further suggesting that the action of peroxynitrite was not completely due to its conversion to NO or NO donors. 相似文献
18.
Alenka Trampu-Bakija Janez Jazbec Barbara Faganel-Kotnik 《Journal of Medical Biochemistry》2020,39(4):422
BackgroundLight transmission aggregometry with lumiaggregometry are methods commonly recommended as a first-line test in platelet dysfunction diagnostic work-up. They are poorly standardized and usually performed in specialized laboratories. For proper interpretation, each laboratory should establish its own diagnostic approach in order to recognize abnormal aggregation patterns. The aim of this study was to measure plasma lumiaggregometry with basic agonists to establish the analyzer-reagent reference intervals (RI) for adults and to test the method response to aspirin.MethodsThe Chrono-Log Model 700 lumiaggregometer using Chrono-Par and Chrono-lume reagents (Chrono-Log Corp., Havertown, PA, USA) was used to measure the maximal aggregation and adenosine triphosphate release using adenosine diphosphate (2 μmol/L), collagen (2 μg/mL), arachidonic acid (1 μmol/L), epinephrine (5.5 μmol/L) and ristocetin (1.25 mg/mL), and thrombin (1 U/mL). The effect of aspirin on platelet aggregation and granule release was inspected.ResultsRIs derived from 40 healthy adults were calculated using the non-parametric approach. Wider intervals and low lower limits were determined for weak agonist as well as absence or impaired aggregation in up to one of 7 healthy controls. The response of platelets to aspirin shows response comparable to previously reported study.ConclusionsLocally established RI in our study enable us to investigate platelet function in patients with a high probability of bleeding disorders. Values are agonist and equipment specific. The variability of the method can be reduced by considering standardized preanalytical and analytical variables. Pathological results must be interpreted in the context of other hemostasis test results and clinical findings. 相似文献
19.
Kunio Tanaka Yoshiteru Harada Masako Iwata Makoto Katori 《Prostaglandins & other lipid mediators》1980,20(2):255-268
Anti-aggregating activity of 7-ethoxycarbonyl-6,8-dimethyl-4-hydroxymethyl-1(2H)-phthalazinone (EG-626) was tested using rabbit platelets in vitro. EG-626 alone, when added before, prevented platelet aggregation induced by ADP, as did PGI2, papaverine and dipyridamole. Spontaneous disaggregation was also accelerated when EG-626 was added after the maximal aggregation induced by ADP. EG-626 alone also inhibited platelet aggregation induced by collagen and arachidonic acid. ID50s of these agents in ADP-induced aggregation were 7–9 nM for PGI2, 223 μM for EG-626, 266 μM for papaverine and 957 μM for dipyridamole. When EG-626 was used in combination with PGI2, a threshold dose (50 μM) of EG-626 potentiated the anti-aggregating effect of subthreshold dose (3 nM) of PGI2 upto 100% inhibition in collagen-induced platelet aggregation. The marked potentiating effect of EG-626 was accompanied by an accumulation of cyclic AMP in the platelets. These effects might be due to inhibition of phosphodiesterase. Papaverine and dipyridamole, other phosphodiesterase inhibitors, also potentiated the anti-aggregating activity of PGI2. The activity of papaverine, however, was one eighth of EG-626 and that of dipyridamole was much less. The most effective combination of PGI2 and EG-626 to induce 50% inhibition was obtained with 20% of ID50 of each agent, whereas that of PGI2 and papaverine or dipyridamole was 39 or 41%, respectively. 相似文献