scholarly journals Inhibitory Effect of Aprotinin on the Activation Process of Contact Factors and Platelet Aggregation

1977 ◽  
Author(s):  
I. Yamaguchi ◽  
Y. Yano ◽  
T. Kitahara ◽  
M. Yatabe ◽  
M. Ukita ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Inhibitory Action ◽  
Enzyme Inhibitor ◽  
Inhibitory Effect ◽  
Release Mechanism ◽  
Activation Process ◽  
Plasma Kallikrein ◽  
Factor Xii ◽  
Clotting Time ◽  
Plasma Factors

It has been reported by several investigators that aprotinin demonstrates inhibitory action on the process of intrinsic blood thromboplastin generation. In this paper the authors will present the facts that on the hydrolytic action of plasma kallikrein, and on the activation process of plasma prekallikrein as well, the inhibitory action of aprotinin is indicated by the use of chromozym PK assay and the latter process might be caused by the inhibition of factor XII activated with Kaolin, and as to platelet aggregation induced by thrombin, aprotinin also plays the inhibitory effect which is more sensitive than the antithrombin activity of aprotinin measured by thrombin clotting time. However, the inhibitory effect of aprotinin on platelets might be caused not only by antithrombic action of this enzyme inhibitor, but also other influence of the inhibitor on release mechanism of the platelets, because epinephrine induced platelet aggregation can be disturbed by the addition of this inhibitor. In summary it mighy be suggested in this study that the clinical use of aprotinin preparation might be one way for anticoagulant thrapy on thrombotic deseases associated with intrinsic hypercoagulability of plasma factors and platelets.

Mechanism of the Antiplatelet Action of Dipyridamole in Whole Blood: Modulation of Adenosine Concentration and Activity

1986 ◽  
Vol 55 (01) ◽  
pp. 012-018 ◽  
Author(s):  
Paolo Gresele ◽  
Jef Arnout ◽  
Hans Deckmyn ◽  
Jos Vermylen
Keyword(s):  
Platelet Aggregation ◽  
Adenosine Receptor ◽  
Whole Blood ◽  
Blood Cells ◽  
Inhibitory Action ◽  
Phosphodiesterase Inhibitor ◽  
Inhibitory Effect ◽  
Adenosine Concentration ◽  
Pharmacological Studies

SummaryDipyridamole inhibits platelet aggregation in whole blood at lower concentrations than in plasma. The blood cells responsible for increased effectiveness in blood are the erythrocytes. Using the impedance aggregometer we have carried out a series of pharmacological studies in vitro to elucidate the mechanism of action of dipyridamole in whole blood. Adenosine deaminase, an enzyme breaking down adenosine, reverses the inhibitory action of dipyridamole. Two different adenosine receptor antagonists, 5’-deoxy-5’-methylthioadenosine and theophylline, also partially neutralize the activity of dipyridamole in blood. Enprofylline, a phosphodiesterase inhibitor with almost no adenosine receptor antagonistic properties, potentiates the inhibition of platelet aggregation by dipyridamole. An inhibitory effect similar to that of dipyridamole can be obtained combining a pure adenosine uptake inhibitor (RE 102 BS) with a pure phosphodiesterase inhibitor (MX-MB 82 or enprofylline). Mixing the blood during preincubation with dipyridamole increases the degree of inhibition. Lowering the haematocrit slightly reduces the effectiveness.Although we did not carry out direct measurements of adenosine levels, the results of our pharmacological studies clearly show that dipyridamole inhibits platelet aggregation in whole blood by blocking the reuptake of adenosine formed from precursors released by red blood cells following microtrauma. Its slight phosphodiesterase inhibitory action potentiates the effects of adenosine on platelets.

Potentiating Effect of Adenosine on Other Inhibitors of Platelet Aggregation

1972 ◽  
Vol 27 (02) ◽  
pp. 252-262 ◽  
Author(s):  
M. Murakami ◽  
K. Odake ◽  
M. Takase ◽  
K. Yoshino
Keyword(s):  
Platelet Aggregation ◽  
Inhibitory Action ◽  
Prostaglandin E1 ◽  
Adenine Nucleotide ◽  
Adenine Nucleotides ◽  
Inhibitory Effect ◽  
Human Platelets ◽  
The Other ◽  
Other Hand ◽  
Adp Release

SummaryAdenosine was rapidly incorporated into human platelets, and the inhibitory effect of adenosine on platelet aggregation was correlated with the incorporation process. Adenosine potentiated the inhibitory action of other inhibitors, such as dipyridamole, prostaglandin E1 and Y-3642. The inhibition of aggregation was associated with the preservation of platelet adenine nucleotides and the prevention of ADP release. On the other hand, the radioactive adenine nucleotide pattern of platelets was not substantially affected by inhibitors. The relation of inhibition of aggregation with ADP release was discussed.

Effect of Acetyl Salicylic Acid on Platelet Function in Yivo

1975 ◽  
Author(s):  
A. A. Hassanein ◽  
N. Afifi ◽  
M. Badr
Keyword(s):  
Salicylic Acid ◽  
Single Dose ◽  
Platelet Aggregation ◽  
Inhibitory Effect ◽  
Acetyl Salicylic Acid ◽  
Clotting Time ◽  
Significant Prolongation ◽  
Platelet Disaggregation ◽  
Platelet Release ◽  
Coagulation Pathway

The ingestion of a single dose of 300 mg. acetyl salicylic acid (ASA) cause after two hours, significant diminution in ADP-induced platelet aggregation and increase in platelet disaggregation. The calcium-induced platelet aggregation test, a turbidimetric modification of the Chandler tube technique, showed significant prolongation in the onset of aggregation and in the clotting time. A test based on the contact product forming activity of platelets showed inhibition after ASA intake.It is suggested that acetyl salicylic acid in addition to its inhibitory effect on platelet release reaction, also affects primary aggregation by ADP and possibly interferes with the ability of platelets to activate the contact system of the intrinsic blood coagulation pathway.

Inhibition of Thrombin-, Epinephrine- and Collagen-Induced Platelet Aggregation by α1-Acid Glycoprotein

1979 ◽  
Author(s):  
P. Andersen ◽  
C. Eika
Keyword(s):  
Platelet Aggregation ◽  
Platelet Rich Plasma ◽  
Adenosine Diphosphate ◽  
Inhibitory Effect ◽  
Human Platelets ◽  
Clotting Time ◽  
Acid Glycoprotein ◽  
High Concentrations ◽  
Spontaneous Platelet Aggregation ◽  
Induced Aggregation

α1-Acid glycoprotein (α1,-acid GP) isolated from human plasma was found to inhibit thrombin-induced aggregation of washed human platelets (0.05 NIH U/ml final conc.), and inhibition was complete with physiological concentrations of α1-acid GP (1.0-1.5 g/1 final conc.). The inhibitory effect seemed to occur immediately on thrombin addition, thus similar to the effect of heparin previously observed. As opposed to heparin, however, α1-acid GP did not affect spontaneous platelet aggregation. Furthermore, α1-acid GP (in optimal cone.) reduced the combined inhibitory effect of heparin and antithrombin III on thrombin-induced platelet aggregation, thus consistent with the previous findings using heparin thrombin clotting time.Snyder and Coodley (1976) found α1-acid GP to inhibit platelet aggregation induced by epinephrine and adenosine diphosphate in platelet-rich plasma. As we also found α1-acid GP to inhibit collagen-induced platelet aggregation, α1-acid GP may possibly act as an inhibitor of the release reaction though fairly high concentrations (10 mg/ml final cone.) was needed for complete inhibition.

Inhibitory effects of antibiotics on platelet aggregation in vitro

1997 ◽  
Vol 16 (11) ◽  
pp. 662-666 ◽  
Author(s):  
Hiroko Kariyazono ◽  
Kazuo Nakamura ◽  
Terutoshi Shinkawa ◽  
Yukinori Moriyama ◽  
Hitoshi Toyohira ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Blood Concentration ◽  
Chemical Structure ◽  
Inhibitory Action ◽  
Adenosine Diphosphate ◽  
Inhibitory Effect ◽  
Carboxyl Group ◽  
Inhibitory Effects ◽  
Induced Aggregation

1 We evaluated in vitro inhibitory effects of six types of antibiotic, aztreonam (AZT), cefamandole (CMD), cefmetazole (CMZ), cefotiam (CTM), flomoxef (FMOX) and latamoxef (LMOX), on platelet aggregation, using healthy volunteers' blood. Four types-FMOX, LMOX, CTM and CMD-inhibited, in concentration of 2500 ?g/ml, the secondary aggregation induced by 3.0 ?M adenosine diphosphate (ADP), and also inhibited the aggregation induced by 0.5 ?g/ml collagen. AZT in the same concentration, did not inhibit the aggregation induced by collagen, and it inhibited only ADP induced aggregation. CMZ, in the same concentration, inhibited neither of the two aggregations. 2 The inhibitory effects of the antibiotics on collagen- induced aggregation were dependent on the concen tration of respective antibiotics. When classified by the strength of inhibitory action, LMOX and FMOX were strong, followed by CTM and CMD. The action of AZT and CMZ was weak. In particular, LMOX showed a 32% inhibitory effect at concentration of 50 ?g/ml, a level near the blood concentration obtained with clinical usual dose. 3 No relationship was observed between inhibitory effects of antibiotics on ADP- or collagen-induced aggregation and the presence or absence of carboxyl group and/or N-methyltetrazolethiol group in the chemical structure.

Effects of N-(2-Diethylaminoethyl)-N-(2-hydroxy- 2-phenylethyl)-2,5-dichloroaniline (AN 162) on Platelet Function and Blood Coagulation

1971 ◽  
Vol 26 (03) ◽  
pp. 576-587
Author(s):  
R. D Mac Kenzie ◽  
T. R Blohm
Keyword(s):  
Platelet Aggregation ◽  
Blood Clotting ◽  
Platelet Rich Plasma ◽  
Adenosine Diphosphate ◽  
Inhibitory Effect ◽  
Clotting Time ◽  
Clotting Factors ◽  
Platelet Factor ◽  
Inhibition Of Platelet Aggregation

SummaryWhen AN 162 was added to human citrated platelet-rich plasma at 30-300 µg/ml, it inhibited platelet aggregation induced by adenosine diphosphate, collagen, and thrombin. When AN 162 was given orally to guinea pigs at 30 to 100 mg/kg, an in vivo inhibitory effect on platelet aggregability was found. Though it activated platelet factor 3, the concentration of AN 162 required for substantial activation was greater than that for inhibition of platelet aggregation. No effect on plasma clotting factors was found at or below 300 µg/ml. Slight prolongation of whole blood clotting time was found in the rat and monkey.

Efffct of Heparin-CI ina Complex on the Action of Kallikrein

1979 ◽  
Author(s):  
S. Ikematsu ◽  
H. Tamura ◽  
K. Fukutake
Keyword(s):  
Inhibitory Action ◽  
Plasma Kallikrein ◽  
Factor Xii ◽  
Amidolytic Activity ◽  
Clotting Factors ◽  
Contact Phase ◽  
Normal Human ◽  
Free Plasma ◽  
Second Peak ◽  
Blood Clotting Factors

CI INA has been known to show not only the inhibitory action on CI esterase, but also the inhibition of blood clotting factors including factor XI, factor XII, plasma kallikrein and plasmin. In this paper the authors attempt the following studies to elucidate the function of heparin-CI INA complex in the field of contact phase. By the addition of heparin into normal human plasma the pattern of cross immunoelectrophoresls of CI INA becomes to show three peaks indicating a complex formation of heparin. CI INA and other clotting factors, which is reversible to move to an original peak by the addition of Protamin sulfate. And it has been analysed that the first peak consists of a complex of heparin-CI INA complex with factors XI and XII and the second peak is a complex of heparin-CI INA and the third peak shows a complex of heparin-CI INA with kallikrein and plasmin. On the observation of inhibitory action of heparin-CI INA complex by the use of chromogenic substrate (S-2302) method for plasma kallikrein assay, it is conformed that the inhibitory action of CI INA on kallikrein is enhanced in parallel with the increasing amount of heparin added into the tested plasma, and the same tendency is observed on the experiment with AT-III free plasma. In conclusion it is strongly suggested that heparin-CI INA complex might be able to form a complest with kallikrein to inhibit its amidolytic activity more effectively than CI INA without heparin does.

Phospholipase C from Clostridium Perfringens Induces Human Platelet Aggregation in Plasma

1988 ◽  
Vol 59 (02) ◽  
pp. 236-239 ◽  
Author(s):  
Giovanna Barzaghi ◽  
Chiara Cerletti ◽  
Giovanni de Gaetano
Keyword(s):  
Platelet Aggregation ◽  
Receptor Antagonist ◽  
Phospholipase C ◽  
Clostridium Perfringens ◽  
Human Platelet ◽  
Ex Vivo ◽  
Platelet Rich Plasma ◽  
Platelet Activating Factor ◽  
Inhibitory Effect ◽  
Thromboxane Receptor Antagonist

SummaryWe studied the aggregating effect of different concentrations of phospholipase C (PLC) (extracted from Clostridium perfringens) on human platelet-rich plasma (PRP). PRP was preincubated with PLC for 3 min at 37° C and the platelet aggregation was followed for 10 min. The threshold aggregating concentration (TAG) of PLC was 3-4 U/ml.We also studied the potentiation of PLC with other stimuli on platelet aggregation. Potentiating stimuli, such as arachidonic acid (AA), ADP. Platelet Activating Factor (PAF) and U-46619 (a stable analogue of cyclic endoperoxides) were all used at subthreshold concentrations. We also studied the possible inhibitory effect of aspirin, apyrase, TMQ, a prostaglandin endoper- oxide/thromboxane receptor antagonist and BN-52021, a PAF receptor antagonist. Only aspirin and apyrase were able to reduce aggregation induced by PLC alone and PLC + AA and PLC + ADP respectively. TMQ and BN-52021 were inactive. In ex vivo experiments oral aspirin (500 mg) partially inhibited platelet aggregation induced by PLC alone, PLC + AA and PLC + ADP 2 and 24 h after administration. Aspirin 20 mg for 7 days also reduced aggregation induced by PLC + AA.

Effect of Dipyridamole on Spontaneous Platelet Aggregation in Whole Blood Decreases with the Time After Venepuncture: Evidence for the Role of ADP

1987 ◽  
Vol 58 (02) ◽  
pp. 744-748 ◽  
Author(s):  
A R Saniabadi ◽  
G D O Lowe ◽  
J C Barbenel ◽  
C D Forbes
Keyword(s):  
Platelet Aggregation ◽  
Correlation Coefficient ◽  
Whole Blood ◽  
Blood Platelet ◽  
Inhibitory Effect ◽  
Time Interval ◽  
Adp Receptor ◽  
Spontaneous Platelet Aggregation

SummarySpontaneous platelet aggregation (SPA) was studied in human whole blood at 3, 5, 10, 20, 30, 40 and 60 minutes after venepuncture. Using a whole blood platelet counter, SPA was quantified by measuring the fall in single platelet count upon rollermixing aliquots of citrated blood at 37° C. The extent of SPA increased with the time after venepuncture, with a correlation coefficient of 0.819. The inhibitory effect of dipyridamole (Dipy) on SPA was studied: (a) 10 μM at each time interval; (b) 0.5-100 μM at 3 and 30 minutes and (c) 15 μM in combination with 100 μM adenosine, 8 μM 2-chloroadenosine (2ClAd, an ADP receptor blocker) and 50 μM aspirin. There was a rapid decrease in the inhibitory effect of Dipy with the time after venepuncture; the correlation coefficient was -0.533. At all the concentrations studied, Dipy was more effective at 3 minutes than at 30 minutes after venepuncture. A combination of Dipy with adenosine, 2ClAd or aspirin was a more effective inhibitor of SPA than either drug alone. However, when 15 μM Dipy and 10 μM Ad were added together, the inhibitory effect of Dipy was not increased significantly, suggesting that Dipy inhibits platelet aggregation independent of Ad. The increase in SPA with the time after venepuncture was abolished when blood was taken directly into the anticoagulant containing 5 μM 2ClAd. It is suggested that ADP released from the red blood cells is responsible for the increased platelet aggregability with the time after venepuncture and makes a serious contribution to the artifacts of in vitro platelet function studies.

The Inhibition of Platelet Aggregation by an Aorta Intima Extract

1974 ◽  
Vol 32 (02/03) ◽  
pp. 417-431 ◽  
Author(s):  
A. du P Heyns ◽  
D. J van den Berg ◽  
G. M Potgieter ◽  
F. P Retief
Keyword(s):  
Platelet Aggregation ◽  
Degradation Products ◽  
Adenosine Diphosphate ◽  
Inhibitory Effect ◽  
Protective Role ◽  
Vascular Trauma ◽  
Wear And Tear ◽  
Sequential Addition ◽  
Aggregation Activity

SummaryThe platelet aggregating activity of extracts of different layers of the arterial wall was compared to that of Achilles tendon. Arterial media and tendon extracts, adjusted to equivalent protein content as an index of concentration, aggregated platelets to the same extent but an arterial intima extract did not aggregate platelets. Platelet aggregation induced by collagen could be inhibited by mixing with intima extract, but only to a maximum of about 80%. Pre-mixing adenosine diphosphate (ADP) with intima extracts diminished the platelet aggregation activity of the ADP. Depending on the relationship between ADP and intima extract concentrations aggregating activity could either be completely inhibited or inhibition abolished. Incubation of ADP with intima extract and subsequent separation of degradation products by paper chromatography, demonstrated a time-dependent breakdown of ADP with AMP, adenosine, inosine and hypoxanthine as metabolic products; ADP removal was complete. Collagen, thrombin and adrenaline aggregate platelets mainly by endogenous ADP of the release reaction. Results of experiments comparing inhibition of aggregation caused by premixing aggregating agent with intima extract, before exposure to platelets, and the sequential addition of first the intima extract and then aggregating agent to platelets, suggest that the inhibitory effect of intima extract results from ADP breakdown. It is suggested that this ADP degradation by intima extract may play a protective role in vivo by limiting the size of platelet aggregates forming at the site of minimal “wear and tear” vascular trauma.

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