Diurnal variation in melatonin effect on adenosine triphosphate and serotonin release by human platelets

Abstract. The effect of the pineal hormone melatonin on adenosine diphosphate-induced human platelet aggregation and adenosine triphosphate release was assessed in platelet-rich plasma obtained from normal volunteers at 08.30 and 20.30 h. In 10−7-10−5 mol/l concentrations melatonin inhibited ADP-induced platelet aggregation only in the evening (p<0.05). ADP-induced ATP release, an index of platelet secretory processes, showed a generally greater, dose-dependent inhibition after adding melatonin (10−9-10−5 mol/l) at 20.30 h as compared with 08.30 h. The inhibitory activity of melatonin (10−9-10−5 mol/l) on [3H]serotonin release elicited by thrombin in washed human platelets obtained from normal volunteers was dose-dependent; the effect was generally greater at 20.30 h. The activity of the potent platelet anti-aggregating agent prostacyclin did not exhibit diurnal differences with respect to impairing ADP-induced platelet-rich plasma aggregation. These results indicate the existence of a diurnal variation of sensitivity to melatonin in human platelets.

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Endotoxin-Induced Platelet Activation in Human Whole Blood In Vitro

Thrombosis and Haemostasis ◽

10.1055/s-0038-1647499 ◽

1988 ◽

Vol 59 (03) ◽

pp. 378-382 ◽

Cited By ~ 11

Author(s):

Gyorgy Csako ◽

Eva A Suba ◽

Ronald J Elin

Keyword(s):

Platelet Aggregation ◽

Whole Blood ◽

Human Platelet ◽

Platelet Rich Plasma ◽

Atp Release ◽

Human Platelets ◽

Lag Phase ◽

Human Whole Blood ◽

Dose Dependent

SummaryThe effect of purified bacterial endotoxin was studied on human platelets in vitro. In adding up to 1 μg/mL of a highly purified endotoxin, we found neither aggregation nor ATP release in heparinized or citrated human platelet-rich plasma. On the other hand, endotoxin at concentrations as low as a few ng/mL (as may be found in septic patients) caused platelet aggregation in both heparinized and citrated human whole blood, as monitored by change in impedance, free platelet count, and size. Unlike collagen, the platelet aggregation with endotoxin occurred after a long lag phase, developed slowly, and was rarely coupled with measurable release of ATP. The platelet aggregating effect of endotoxin was dose-dependent and modified by exposure of the endotoxin to ionizing radiation. Thus, the activation of human platelets by “solubilized” endotoxin in plasma requires the presence of other blood cells. We propose that the platelet effect is mediated by monocytes and/or neutrophils stimulated by endotoxin.

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Effects of Lead Acetate on Platelet Aggregation, Ultrastructure and Serotonin Release

Thrombosis and Haemostasis ◽

10.1055/s-0038-1653698 ◽

1971 ◽

Vol 26 (03) ◽

pp. 455-466 ◽

Cited By ~ 1

Author(s):

R. B Davis ◽

G. C Holtz

Keyword(s):

Platelet Aggregation ◽

Platelet Function ◽

Lead Acetate ◽

Platelet Rich Plasma ◽

Adenosine Diphosphate ◽

Blood Platelet ◽

Human Platelets ◽

Serotonin Release ◽

Aggregation Of Platelets

SummaryThe effects of lead on blood platelet function and ultrastructure have been investigated. Lead acetate was injected intravenously in 27 rats and was added to rat and human platelet rich plasma in vitro. In vitro studies showed that concentrations of 2.5 × 10-3 M lead acetate reduced or blocked aggregation of rat and human platelets by adenosine diphosphate, collagen, and thrombin. Radioactive serotonin release from human platelets was inhibited by 10-4 M lead acetate. One hour after the injection of lead, platelet aggregation by thrombin was reduced, but platelet aggregation by adenosine diphosphate and collagen showed little change. Three days after lead, aggregation of platelets by collagen and thrombin was blocked and aggregation by adenosine diphosphate reduced. Thrombocytopenia was present 4 days after intravenous lead acetate. Electron micrographs of platelets showed that the mean number of mitochondria per platelet was increased, whereas alpha granules were reduced. Dense bodies were not significantly changed. Lead acetate affects platelet function in concentrations reported in human bone marrow in lead poisoning, and may relate to the binding of free sulfhydryl groups by lead.

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Collagen-Induced Platelet Aggregation: -Evidence Against the Essential Role of Platelet Adenosine Diphosphate

Thrombosis and Haemostasis ◽

10.1055/s-0038-1657015 ◽

1979 ◽

Vol 42 (04) ◽

pp. 1193-1206 ◽

Cited By ~ 9

Author(s):

Barbara Nunn

Keyword(s):

Platelet Aggregation ◽

Time Course ◽

Essential Role ◽

Atp Release ◽

Adenosine Diphosphate ◽

Human Platelets ◽

High Doses ◽

Induced Aggregation

SummaryThe hypothesis that platelet ADP is responsible for collagen-induced aggregation has been re-examined. It was found that the concentration of ADP obtaining in human PRP at the onset of aggregation was not sufficient to account for that aggregation. Furthermore, the time-course of collagen-induced release in human PRP was the same as that in sheep PRP where ADP does not cause release. These findings are not consistent with claims that ADP alone perpetuates a collagen-initiated release-aggregation-release sequence. The effects of high doses of collagen, which released 4-5 μM ADP, were not inhibited by 500 pM adenosine, a concentration that greatly reduced the effect of 300 μM ADP. Collagen caused aggregation in ADP-refractory PRP and in platelet suspensions unresponsive to 1 mM ADP. Thus human platelets can aggregate in response to collagen under circumstances in which they cannot respond to ADP. Apyrase inhibited aggregation and ATP release in platelet suspensions but not in human PRP. Evidence is presented that the means currently used to examine the role of ADP in aggregation require investigation.

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Preclinical studies of RUC-4, a novel platelet αIIbβ3 antagonist, in non-human primates and with human platelets

Journal of Clinical and Translational Science ◽

10.1017/cts.2019.382 ◽

2019 ◽

Vol 3 (2-3) ◽

pp. 65-74 ◽

Cited By ~ 4

Author(s):

Spandana Vootukuri ◽

Jihong Li ◽

Mark Nedelman ◽

Craig Thomas ◽

Jiang-Kang Jiang ◽

...

Keyword(s):

Platelet Aggregation ◽

Platelet Rich Plasma ◽

Human Platelets ◽

Initial Slope ◽

Receptor Blockade ◽

St Segment Elevation ◽

St Segment ◽

Aggregation Inhibition ◽

Induced Aggregation ◽

Dose Dependent

AbstractIntroduction:We are developing the novel αIIbβ3 antagonist, RUC-4, for subcutaneously (SC)-administered first-point-of-medical-contact treatment for ST segment elevation myocardial infarction (STEMI).Methods:We studied the (1) pharmacokinetics (PK) of RUC-4 at 1.0, 1.93, and 3.86 mg/kg intravenous (IV), intramuscular (IM), and SC in non-human primates (NHPs); (2) impact of aspirin on RUC-4 IC50in human platelet-rich plasma (PRP); (3) effect of different anticoagulants on the RUC-4 IC50in human PRP; and (4) relationship between αIIbβ3 receptor blockade by RUC-4 and inhibition of ADP-induced platelet aggregation.Results:(1) All doses of RUC-4 were well tolerated, but animals demonstrated variable temporary bruising. IM and SC RUC-4 reached dose-dependent peak levels within 5–15 minutes, with T1/2s between 0.28 and 0.56 hours. Platelet aggregation studies in NHPs receiving IM RUC-4 demonstrated >80% inhibition of the initial slope of ADP-induced aggregation with all three doses 30 minutes post-dosing, with subsequent dose-dependent loss of inhibition over 4–5 hours. (2) The RUC-4 IC50for ADP-induced platelet aggregation was unaffected by aspirin treatment (40±9 nM vs 37±5 nM;p= 0.39). (3) The RUC-4 IC50was significantly higher in PRP prepared from D-phenylalanyl-prolyl-arginyl chloromethyl ketone (PPACK)-anticoagulated blood compared to citrate-anticoagulated blood using either thrombin receptor activating peptide (TRAP) (122±17 vs 66±25 nM;p= 0.05;n= 4) or ADP (102±22 vs 54±13;p<0.001;n= 5). (4) There was a close correspondence between receptor blockade and inhibition of ADP-induced platelet aggregation, with aggregation inhibition beginning with ~40% receptor blockade and becoming nearly complete at >80% receptor blockade.Discussion:Based on these results and others, RUC-4 has now progressed to formal preclinical toxicology studies.

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Fibrinogen-independent aggregation and deaggregation of human platelets: studies in two afibrinogenemic patients

Blood ◽

10.1182/blood.v70.1.221.221 ◽

1987 ◽

Vol 70 (1) ◽

pp. 221-226 ◽

Cited By ~ 25

Author(s):

M Cattaneo ◽

RL Kinlough-Rathbone ◽

A Lecchi ◽

C Bevilacqua ◽

MA Packham ◽

...

Keyword(s):

Platelet Aggregation ◽

Plasma Proteins ◽

Platelet Rich Plasma ◽

Platelet Activating Factor ◽

Adenosine Diphosphate ◽

Human Platelets ◽

Human Fibrinogen ◽

Control Subjects ◽

Platelet Aggregates ◽

And Control

Abstract Platelets from two afibrinogenemic patients were used to determine whether fibrinogen is essential for platelet aggregation and to examine whether released fibrinogen contributes to the stabilization of platelet aggregates when platelets have been induced to aggregate and release their granule contents by stimulation with thrombin. The addition of adenosine diphosphate (ADP) to platelet-rich plasma (PRP) or to suspensions of washed platelets from the afibrinogenemic patients caused the formation of small aggregates, which was either not inhibited or only slightly inhibited by the F(ab')2 fragments of an antibody to fibrinogen but was inhibited by an antibody (10E5) to glycoprotein IIb/IIIa. Thus there is a component of ADP-induced platelet aggregation that is not dependent on fibrinogen or other plasma proteins but is dependent on glycoprotein IIb/IIIa. There was little difference in the extent of aggregation and the release of granule contents of normal and afibrinogenemic platelets in response to the release-inducing agents collagen, platelet-activating factor (PAF), sodium arachidonate, or thrombin. With normal or afibrinogenemic platelets, aggregation by thrombin (0.2 U/mL or higher) was not inhibited by the F(ab')2 fragments of an antibody to human fibrinogen. Deaggregation by combinations of inhibitors of platelets aggregated by 1 U/mL thrombin showed no difference between platelets from afibrinogenemic and control subjects, indicating that released fibrinogen does not make a major contribution to the stabilization of platelet aggregates formed by thrombin stimulation.

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Inhibition Of Platelet Aggregation, Malonyldialdehyde And Thromboxane Formation By Hydroperoxides Of Arachidonic Acid

10.1055/s-0038-1652786 ◽

1981 ◽

Author(s):

D Aharonv ◽

J B Smith ◽

M J Silver

Keyword(s):

Arachidonic Acid ◽

Platelet Aggregation ◽

Platelet Rich Plasma ◽

Human Platelets ◽

Lipoxygenase Pathway ◽

Dose Dependent Fashion ◽

Induced Aggregation ◽

Layer Chromatography ◽

Dose Dependent ◽

Thromboxane Formation

The arachidonate hydroperoxides 12-HPETE and 15-HPETE were biosynthesized from arachidonic acid using partially purified human platelet lipoxygenase or soybean lipoxidase respectively, and isolated by thin layer chromatography. Both compounds inhibited the arachidonic acid- induced aggregation of washed human platelets, suspended in calcium-free Krebs Henseleit solution, in a dose dependent fashion at concentrations between 1 and 50 uM. No inhibition was seen with up to 100 uM of these hydroperoxides when platelet -rich plasma was used. 12-HPETE (in micromolar concentrations) inhibited the formation of both thromboxane B2 (radioimmunoassay) and malonyldialdehyde (spectrophotometrie assay) when washed platelets were incubated with arachidonic acid. The 12-hydroxide, 12-HETE also inhibited platelet aggregation and thromboxane formation, but was less potent than 12-HPETE. We suggest that arachidonate hydroperoxide generated in platelets via the lipoxygenase pathway modulates platelet aggregation induced by arachidonic acid by inhibiting thromboxane formation.

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Inhibition and potentiation of platelet function by lysolecithin

Blood ◽

10.1182/blood.v49.1.101.101 ◽

1977 ◽

Vol 49 (1) ◽

pp. 101-112 ◽

Cited By ~ 26

Author(s):

JH Joist ◽

G Dolezel ◽

MP Cucuianu ◽

EE Nishizawa ◽

JF Mustard

Keyword(s):

Platelet Function ◽

Platelet Rich Plasma ◽

Membrane Damage ◽

Adenosine Diphosphate ◽

Lactic Dehydrogenase ◽

Inhibitory Effect ◽

Human Platelets ◽

Serotonin Release ◽

Prolonged Incubation ◽

Induced Aggregation

Abstract The effects of lysolecithin (LPC) on aggregation, serotonin release, shape, and lysis of rabbit, pig, or human platelets in platelet-rich plasma (PRP) or Tyrode albumin solution were examined during prolonged incubation. LPC added to citrated or heparinized PRP from humans or rabbits at a final concentration above 100 muM caused instantaneous inhibition of platelet aggregation induced by adenosine diphosphate (ADP), epinephrine (human PRP only), collagen, or thrombin. The inhibitory effect of LPC was found to be partially reversible over a period of 60–90 min. LPC at final concentrations above 30 muM also caused inhibition of ADP-, collagen-, and thrombin-induced aggregation and collagen- and thrombin-induced release of serotonin in suspensions of rabbit, pig, or human platelets. With washed platelets, the inhibitory effect not only rapidly disappeared but was followed by transient potentiation of aggregation and serotonin release. This potentiating effect of LPC was most pronounced when thrombin was used as stimulus. Both inhibition and potentiation were observed at concentrations of LPC that did not cause a significant change in platelet shape or loss from platelets of lactic dehydrogenase. Inhibition and potentiation were also observed when platelets were added to suspending medium containing LPC, although considerably higher concentrations of LPC were required under these conditions. Potentiation was not observed when LPC was added to citrated or heparinized rabbit or human PRP or to washed rabbit platelets suspended in a medium containing 4% bovine serum albumin. It seemed likely that some or all of the observed effects of LPC on platelet function were due to structural modification of the platelet membrane insufficient to result in gross membrane damage or platelet lysis. In addition, the results of experiments using 14C-LPC seemed to indicate that the observed potentiating effect of LPC on platelet function may be related to its rapid uptake and metabolism by the platelets.

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Studies on the Biological Effects of Ozone: 10. Release of Factors from Ozonated Human Platelets

Mediators of Inflammation ◽

10.1080/09629359990360 ◽

1999 ◽

Vol 8 (4-5) ◽

pp. 205-209 ◽

Cited By ~ 36

Author(s):

G. Valacchi ◽

Velio Bocci

Keyword(s):

Platelet Aggregation ◽

Growth Factor ◽

Transforming Growth Factor ◽

Platelet Rich Plasma ◽

Biological Effects ◽

Transforming Growth Factor Β1 ◽

Human Platelets ◽

Dependent Manner ◽

Dose Dependent ◽

Tgf Β1

In a previous work we have shown that heparin, in the presence of ozone (O3), promotes a dose-dependent platelet aggregation, while after Ca2+chelation with citrate, platelet aggregation is almost negligible. These results led us to think that aggregation may enhance the release of platelet components. We have here shown that indeed significantly higher amount of platelet-derived growth factor (PDGF), transforming growth factor β1 (TGF-β1) and interleukin-8(IL-8) are released in a dose-dependent manner after ozonation of heparinised platelet-rich plasma samples. These findings may explain the enhanced healing of torpid ulcers in patients with chronic limbischemia treated with O3autohaemoteraphy (O3-AHT).

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The Effect of Cold on Platelets. II. Platelet Function After Short-term Storage at Cold Temperatures

Blood ◽

10.1182/blood.v40.5.688.688 ◽

1972 ◽

Vol 40 (5) ◽

pp. 688-696 ◽

Cited By ~ 45

Author(s):

Herman E. Kattlove ◽

Benjamin Alexander ◽

Frances White

Keyword(s):

Platelet Aggregation ◽

Room Temperature ◽

Platelet Rich Plasma ◽

Adenosine Diphosphate ◽

Serotonin Release ◽

Prolonged Storage ◽

Cold Temperatures ◽

Aggregation Of Platelets ◽

Term Storage

Abstract Citrated platelet-rich plasma (PRP) was kept at cold temperatures or room temperature. After 4 hr or more at these temperatures, the PRPs were warmed 1 hr at 37°C. This prevents the spontaneous aggregation seen in chilled PRP that is stirred immediately after warming. Platelet aggregation in response to connective tissue (CT), epinephrine, and adenosine diphosphate (ADP) was considerably greater in the PRPs originally kept at cold temperatures. In addition, chilling would restore the aggregation of platelets whose function had deteriorated due to prolonged storage at warm temperatures. Neither ADP-induced refractoriness, serotonin uptake, or CT-induced serotonin release was affected by cold. Retention in glass bead columns was greater in platelets that had been chilled than in platelets kept at room temperature or 37°C. Thus, the storage of platelets at cold temperatures leads to changes that improve platelet aggregation but may also increase platelet adhesion, which would account for the decreased in vivo survival of platelets preserved for transfusion at cold temperatures.

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The effect of PGI2 and theophylline on the response of platelets subjected to shear stress

Blood ◽

10.1182/blood.v58.4.678.bloodjournal584678 ◽

1981 ◽

Vol 58 (4) ◽

pp. 678-681 ◽

Cited By ~ 1

Author(s):

RA Hardwick ◽

JD Hellums ◽

DM Peterson ◽

JL Moake ◽

JD Olson

Keyword(s):

Shear Stress ◽

Platelet Aggregation ◽

Platelet Rich Plasma ◽

Antiplatelet Agent ◽

Human Platelets ◽

Clinical Applications ◽

Serotonin Release ◽

Large Reduction ◽

Prior Work ◽

Rotational Viscometer

A specially designed rotational viscometer was used to investigate the effects of the antiplatelet agent PGI2 in combination with theophylline on the response of human platelets subjected to shear stress. Samples of citrated platelet-rich plasma (PRP) were exposed to shear stress in the viscometer for a period of 5 min at 23 degrees C. The levels of stress studied ranged from 50 to 300 dynes/sq cm. Pretreatment of the platelets with 0.01 microM PGI2 and 500 microM theophylline before exposure to shear stress caused a large reduction in shear-induced platelet aggregation. However, it was also observed that the PGI2-- theophylline pretreatment concomitantly caused a large increase in shear-induced platelet lysis and serotonin release at stress levels equal to or greater than 150 dynes/sq cm. This observed increase in platelet fragility may have important implications for clinical applications of PGI2. The results are discussed and compared to those obtained in prior work in which platelets were pretreated with acetylsalicylic acid or with PGE1.

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