Incorporation of Labelled Nucleotides and Aggregation of Human Blood Platelets

1966 ◽  
Vol 15 (01/02) ◽  
pp. 052-068 ◽  
Author(s):  
E. W Salzman ◽  
D. A Chambers ◽  
Lena L. Neri
Keyword(s):  
Platelet Aggregation ◽  
Methyl Ester ◽  
Human Blood ◽  
Platelet Rich Plasma ◽  
Adenine Nucleotides ◽  
Blood Platelets ◽  
Temperature Dependent ◽  
Sequence Of Events ◽  
Plasma Factor ◽  
Human Blood Platelets

SummaryAddition of ADP-8-C14 to platelet-rich plasma results in platelet radioactivity through a series of temperature-dependent reactions involving stepwise dephosphorylation of the nucleotide in plasma and then incorporation of the adenosine residue by the platelet, where it participates as a precursor in synthesis of platelet adenine nucleotides. This sequence of events, which requires a heat-labile nondialysable plasma factor, is blocked by 0.01 M KCN, by EDTA, by arginine methyl ester, by adenosine, and by AMP.ADP-induced platelet aggregation does not require the reactions outlined above and proceeds without ADP - breakdown and without binding of the ADP- molecule to the platelet. A possible mechanism of this phenomenon is suggested.

Synergism Between Adrenaline and Adenine Nucleotides in Producing Platelet Aggregation Responses

1979 ◽  
Author(s):  
B. Oppenheim ◽  
M.B.H. Youdim
Keyword(s):  
Platelet Aggregation ◽  
Synergistic Effect ◽  
Human Blood ◽  
Adenine Nucleotides ◽  
Blood Platelets ◽  
Second Phase ◽  
Structural Analogue ◽  
Aggregation Response ◽  
Human Blood Platelets

Recently we have shown that 5′-adenylylimidodiphosphate (AIP), a structural analogue of ATP, causes a transient aggregation of human blood platelets similar to that produced by 5-hydroxytryptamine (5-HT) (Brit. J. Pharmacol. 1979, in press). In addition AIP strongly inhibits the second phase of aggregation induced by adrenaline (A), noradrenaline, ADP and irreversible 5-HT when such a response is obtained. However, it does not affect collagen response, indicating that AIP is an inhibitor of release I (i.e. release is reversible. Like 5-HT, the aggregation to AIP can be enhanced by pretreatment (30-60 sec.) with low (0.1-0.5 μM) non-aggregating concentrations of A, but without exhibiting a second phase of aggregation. The synergistic effect of A (but not isoproterenol, 10-100 μM) was also observed with ATP and ADP. ATP by itself does not produce an aggregation response but it causes a 5-HT like response after preincubation with A. The potentiating effects of A on aggregation responses are selectively prevented by phentolamine (10 μM) but not by proparanolol (10 μM). The results suggest an α-adrenergic mediated effect.

scholarly journals Survival and recovery of human platelets stored for five days in a non- plasma medium

Blood ◽  
1986 ◽  
Vol 67 (3) ◽  
pp. 672-675 ◽  
Author(s):  
GA Adams ◽  
SD Swenson ◽  
G Rock
Keyword(s):  
Platelet Aggregation ◽  
Human Blood ◽  
Blood Platelets ◽  
Human Platelets ◽  
Plasma Medium ◽  
Release Reaction ◽  
In Vivo Recovery ◽  
Human Blood Platelets

Abstract Human blood platelets were stored for five days as concentrates in 60 mL of: (a) plasma; (b) non-plasma medium with anticoagulant; and (c) non-plasma medium without anticoagulant. All preparations were equally functional when tested for platelet aggregation and release reaction in response to single agonist or synergistic pairs of agonists in vitro. Platelets stored in non-plasma medium with anti-coagulant had lower kallikrein, fibrino(gen)peptide A, lactate, and beta-thromboglobulin than did plasma controls after five days. In vivo recovery and survival of platelets stored in non-plasma medium with anticoagulant were 51.2% +/- 4.3% and 8.7 +/- 0.3 days, respectively, which were not statistically different from plasma controls of 39.2% +/- 4.9% and 7.2 +/- 0.8 days, respectively. It is concluded that platelets can be stored for five days in a non-plasma medium and still have good in vivo recoveries and survivals.

scholarly journals The synthetic RGDS peptide inhibits the binding of fibrinogen lacking intact alpha chain carboxyterminal sequences to human blood platelets

Blood ◽  
1987 ◽  
Vol 69 (3) ◽  
pp. 950-952 ◽  
Author(s):  
EI Peerschke ◽  
DK Galanakis
Keyword(s):  
Platelet Aggregation ◽  
Human Blood ◽  
Blood Platelets ◽  
Adenosine Diphosphate ◽  
Competitive Inhibitor ◽  
Minor Role ◽  
Solution Ph ◽  
Alpha Chain ◽  
A Minor ◽  
Human Blood Platelets

Abstract The alpha chain 572–574 Arg-Gly-Asp sequence of fibrinogen appears to play only a minor role in platelet aggregation based on the ability of fibrinogen preparations lacking alpha chain carboxyterminal segments to support platelet aggregation, but synthetic Arg-Gly-Asp-Ser (RGDS) peptides are capable of inhibiting platelet aggregation and fibrinogen binding. The present study thus examined the ability of RGDS peptides to inhibit platelet interactions with a plasmic degradation product of fibrinogen (8D–50) that resembles an intermediate fragment X. Gel- filtered, human blood platelets suspended in 0.01 mol/L HEPES-buffered modified Tyrode's solution, pH 7.5, were stimulated with 20 mumol/L adenosine diphosphate and the binding of 125I-labeled 8D–50 or intact fibrinogen (0.01 to 0.6 mg/mL) assessed in the presence of 0 to 117 mumol/L RGDS. The data revealed that RGDS decreased the apparent affinity of 8D–50 and intact fibrinogen for platelets but did not affect the maximum number of binding sites. RGDS thus appears to be a competitive inhibitor not only of intact fibrinogen (Ki = 12 +/- 2 mumol/L) but also of 8D–50 (Ki = 15 +/- 3 mumol/L) (mean +/- SD, n = 3).

scholarly journals Short communication: possible association of newly absorbed serotonin with nonmetabolic, granule-located adenine nucleotides in human blood platelets

Blood ◽  
1975 ◽  
Vol 45 (3) ◽  
pp. 413-416
Author(s):  
H Holmsen ◽  
CA Setkowsky ◽  
HJ Day
Keyword(s):  
Guinea Pig ◽  
Human Blood ◽  
Short Communication ◽  
Adenine Nucleotides ◽  
Blood Platelets ◽  
Human Platelets ◽  
Serotonin Release ◽  
Release Reaction ◽  
Human Blood Platelets

[3H]-adenine-labeled human platelets in plasma were incubated with or without nonradioactive serotonin. Release reaction was then induced by ADP, epinephrine, collagen, or thrombin. Platelets that had been incubated with serotonin released four times as much serotonin as platelets incubated without serotonin. The specific radioactivities of the ATP and ADP released to plasma during release reaction induced with all four inducers were the same in both systems. This shows that when serotonin is taken up by human platelets, it enters the compartment containing nonmetabolic, granula-stored ATP, and not the compartment with metabolic extragranular ATP. These results suggest that the mechanism of serotonin storage in human platelets is similar to that in other species investigated, i.e., rabbit, guinea pig, and pig.

The Use of a Chelating Ion-Exchange Resin to Evaluate the Effects of the Extracellular Calcium Concentration on Adenosine Diphosphate Induced Aggregation of Human Blood Platelets

1976 ◽  
Vol 36 (01) ◽  
pp. 208-220 ◽  
Author(s):  
Stanley Heptinstall
Keyword(s):  
Platelet Aggregation ◽  
Ion Exchange ◽  
Human Blood ◽  
Calcium Concentration ◽  
Exchange Resin ◽  
Blood Platelets ◽  
Adenosine Diphosphate ◽  
Ion Exchange Resin ◽  
Extracellular Calcium ◽  
Human Blood Platelets

Summary1. An ion-exchange resin, Chelex 100, has been used to prepare suspensions of human blood platelets in calcium and magnesium depleted plasma.2. Extracellular calcium is required for platelet aggregation when induced by adenosine diphosphate (ADP). Magnesium only supports aggregation provided that a small amount of calcium is present in the plasma.3. The extent of platelet aggregation depends upon the concentration of calcium in the plasma. There is an optimum concentration of calcium with which the maximum amount of aggregation is obtained in response to any single concentration of ADP. This optimum calcium concentration is below the physiological level. Higher calcium concentrations reduce the extent of aggregation by enhancing the rate of disaggregation and high magnesium concentrations have the same effect. It is possible that free ADP levels are reduced as a result of ADP-divalent cation complex formation.4. Platelets were found to contain 18.6 (S.D. ±1.1) × 10–6 mol Ca and 9.3 (S.D. ±1.0) × 10–6 mol Mg per 1011 cells.

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