The Effect of Lysed Platelets on Neutralization of Heparin In Vitro with Protamine as Measured by the Activated Coagulation Time (ACT)

1991 ◽  
Vol 66 (02) ◽  
pp. 213-217 ◽  
Author(s):  
Arthur P Bode ◽  
William J Castellani ◽  
Edna D Hodges ◽  
Susan Yelverton
Keyword(s):  
Platelet Rich Plasma ◽  
Coagulation Time ◽  
Platelet Factor ◽  
Platelet Suspension ◽  
Antiheparin Activity ◽  
Unit Increase ◽  
Heparin Anticoagulation ◽  
Heparin Activity ◽  
Activated Coagulation Time

SummaryThe effect of lysed platelets on the activated coagulation time (ACT) was studied in heparinized whole blood during titration with protamine. Frozen-thawed washed platelet suspension, or a chromatography fraction thereof, or autologous frozen-thawed platelet-rich plasma was added in various dilutions to freshly drawn blood anticoagulated with 3,000 USP units/1 heparin. After a 10 min incubation, the amount of protamine needed to restore the ACT to baseline ("protamine titration dose") was determined. We found that the protamine titration dose decreased in proportion to the amount of lysed platelet material added; expressed as a percentage of the total number of platelets present, each unit increase in lysed platelets produced a 1.7% ±0.8 (SD) reduction in the protamine dose needed to normalize the ACT. A heparin activity assay showed that this effect was not due to antiheparin activity of lysed platelets such as platelet factor 4 (PF4). Our data indicate that the procoagulant activity of platelet membranes reduced the sensitivity of the ACT to heparin. These findings suggest that membranous platelet microparticles may cause an inaccurate calculation, based on the ACT, of a protamine dose to reverse heparin anticoagulation in cardiopulmonary bypass procedures.

Antiheparin Activity of Human Serum and Platelet Factor 4

1973 ◽  
Vol 30 (01) ◽  
pp. 093-105 ◽  
Author(s):  
C.H.J Sear ◽  
L Poller ◽  
F.R.C Path
Keyword(s):  
Molecular Weight ◽  
Ionic Strength ◽  
Blood Serum ◽  
Whole Blood ◽  
Platelet Rich Plasma ◽  
Gel Filtration ◽  
Normal Serum ◽  
Platelet Factor ◽  
Mean Values ◽  
Antiheparin Activity

SummaryThe antiheparin activity of normal serum has been studied by comparing the antiheparin activities of sera obtained from normal whole blood, platelet-rich plasma and platelet-’free’ plasma with a purified platelet extract during differential isoelectric precipitation and by gel filtration chromatography.The mean values for the activity of PRP-serum and PFP-serum were 106% (S.D. 11) and 10% (S.D. 3) of untreated whole blood respectively. The activity of whole blood serum, PRP serum and whole blood serum plus platelet extract precipitated under identical physical conditions, i.e. pH 7.0, I =0.008, indicating that the activities of the three samples are probably associated with PF4. PF4 precipitated from human platelet extract at pH 4.0, but this is probably due to the difference in the two biochemical environments investigated, i.e. serum and platelet extract.The gel filtration experiments revealed striking similarities between the major antiheparin activities of serum and platelet extract. At physiological pH and ionic strength both activities were associated with high molecular weight material, but at physiological pH and elevated ionic strength both activities behaved as much smaller entities of molecular weight between 25,000 and 30,000 daltons and it seems very likely that both activities are associated with the same molecule, i.e. PF4.

In Vivo Protamine Titration Using Activated Coagulation Time to Neutralize Heparin Anticoagulation in Cardiac Surgery: Proof of Concept

2020 ◽  
Vol 34 (9) ◽  
pp. 2369-2374
Author(s):  
Antoine G. Rochon ◽  
Sylvain Bélisle ◽  
Pierre Couture ◽  
Annik Fortier ◽  
Jean-Sébastien Lebon ◽  
...  
Keyword(s):  
Cardiac Surgery ◽  
Proof Of Concept ◽  
Coagulation Time ◽  
Heparin Anticoagulation ◽  
Activated Coagulation Time

scholarly journals Platelet Factor 4 (PF4) and Protamine Neutralisation of Heparin in Plasma

1977 ◽  
Author(s):  
R. Michalski ◽  
D.A. Lane ◽  
D. Pepper ◽  
V.V. Kakkar
Keyword(s):  
Intravenous Injection ◽  
Factor Xa ◽  
Weight Basis ◽  
Platelet Factor 4 ◽  
Assay System ◽  
Platelet Factor ◽  
Protamine Sulphate ◽  
Heparin Activity ◽  
Plasma Heparin

The ability of PF4 and protamine sulphate to neutralise heparin in plasma has been studied using a specific anti-Factor Xa assay and a KCCT assay to measure residual heparin. When heparin is added to plasma in vitro PF4 and protamine neutralise almost equivalent amounts of heparin on a weight basis, 1.0 unit of heparin being neutralised by approximately 20 μg of PF4 and 15 μg of protamine. Similar results are obtained using either of the heparin assays. However, following intravenous injection of heparin only about one half of the circulating heparin could be neutralised in vitro by PF4 or protamine when it was measured by anti-Factor Xa assay. Total neutralisation was obtained with both neutralising agents in the KCCT assay system. These results demonstrate that the choice of assay is important when a protamine titration is used to measure plasma heparin levels, and that PF4 and protamine are unable to totally neutralise circulating antithrombotic heparin activity.

In Vitro and In Vivo Effects of Adrenaline and Phentolamine on Platelet Function

1978 ◽  
Vol 40 (02) ◽  
pp. 428-438 ◽  
Author(s):  
Oreste Ponari ◽  
Emilio Civardi ◽  
Alessandro Megha ◽  
Mario Pini ◽  
Raffaele Poti’ ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Platelet Rich Plasma ◽  
Threshold Concentration ◽  
Two Phase ◽  
Platelet Factor ◽  
Induce Platelet Aggregation ◽  
In Vivo Effects ◽  
In Vivo Administration

Summary In vitro and in vivo effects of adrenaline (ADR) on platelet aggregation, on platelet factor 3 (PF3) availability and on platelet factor 4 (PF4) release were studied in man. Inhibitory action of an alpha-blocker, phentolamine (PHEN) was investigated in the same conditions.The threshold concentration (TC) of ADR inducing the typical two-phase response in aggregation tests when added to platelet-rich plasma (PRP) varied in different pools of plasma, but always induced an evident PF4 release and increased PF3 availability. A further increase in both parameters was obtained with higher concentrations but without any significant dose/response correlation.Adding PHEN alone to PRP did not induce platelet aggregation or modify PF4 release induced by stirring, but it reduced PF3 availability. On the other hand, PHEN prevented the effects of ADR in different platelet tests, at appropriate concentrations.Intravenous infusion of ADR lowered the TC, and increased PF3 availability and PF4 release. In vivo administration of PHEN, in contrast, increased TC and reduced PF3 availability, while PF4 remained unchanged.

PLATELET FUNCTION AND PLASMA FIBRINOGEN IN YOUNG SURVIVORS OF MYOCARDIAL INFARCTION

1987 ◽  
Author(s):  
U Berglund ◽  
H von Schenk ◽  
L Wallentin
Keyword(s):  
Myocardial Infarction ◽  
Platelet Function ◽  
Platelet Reactivity ◽  
Platelet Rich Plasma ◽  
Inhibitory Effect ◽  
Plasma Fibrinogen ◽  
Women Patients ◽  
Platelet Factor ◽  
Young Survivors

An increased liability for thrombosis might be of pathogenetic importance in young survivors of myocardial infarction (MI). In 73 (58 men and 15 women) patients with MI below 45 years of age and 73 matched healthy controls plasma fibrinogen and platelet function tests were studied 3-6 months after the MI. At the time of the MI 77% of the patients were smokers but at the time of the investigation 27% of the patients smoked compared to 37% of the controls. Platelet aggregabi1ity was measured in vitro in platelet-rich plasma (PRP) as maximal aggregation to ADP and collagen. The platelet sensitivity to the inhibitory effect of prostacyclin (PG12) was tested by preincubation of PRP with PG12 before inducing aggregation with ADP 5 μM. Plasma levels of beta-thrombog1obuIin (BTG) and platelet factor 4 (PF4) were measured by RIA methods and plasma fibrinogen by heat precipitation. The table presents the results (means ± SE). * is p<0.04, ** is D<0.02 and ns is non significant.Severe emotional stress preceeding the MI occured in 7 patients - these cases had an increased platelet reactivity to ADP. The fibrinogen level was also elevated by smoking and obesity (multivariate analysis). Conclusion: young MI patients have elevated levels ol fibrinogen and reduced platelet sensitivity to PGI2. This might cause an increased thrombotic tendency.

Effect of New Synthetic Heparin Mimetics on Whole Blood Thrombin Generation In Vivo and In Vitro in Rats

2002 ◽  
Vol 87 (02) ◽  
pp. 238-244 ◽  
Author(s):  
J.P. Hérault ◽  
A. Bernat ◽  
C. Gaich ◽  
J.M. Herbert
Keyword(s):  
Venous Thrombosis ◽  
Charge Density ◽  
Whole Blood ◽  
Thrombin Generation ◽  
Platelet Rich Plasma ◽  
Lag Time ◽  
Drug Candidate ◽  
Platelet Factor

SummaryThe effect of new heparin mimetics (synthetic oligosaccharides) was studied in vitro with regard to thrombin generation (TG) in rat platelet rich plasma (PRP) and whole blood (WB) and in vivo on stasis-induced venous thrombosis in the rat.TG in PRP and in WB was highly dependent on platelet count and strongly influenced by the haematocrit. The peak of TG appeared to be significantly higher in WB than in PRP whereas the endogenous thrombin potential (ETP) was not significantly different under either condition.The effect of hirudin, the synthetic pentasaccharide SR90107/ Org31540 (SP) and heparin were measured on TG in PRP and WB. We then compared the effect of two new synthetic heparin mimetics (SR121903A and SanOrg123781) with potent and comparable antithrombin (AT) mediated activity against factor Xa and thrombin. These two compounds were made of a pentasaccharide with a high affinity to AT, prolonged at the non-reducing end by an oligosaccharide chain recognised by thrombin. In SR121903A, the charge density and charge distribution was analogous to that of heparin whereas in SanOrg123781 the charges were only located on the last 5 saccharides of the non-reducing end of the molecule. In PRP and in WB, SR121903A acted on the lag time and on the AUC whereas SanOrg123781 inhibited thrombin formation with no effect on the lag time. SanOrg123781 was more potent in inhibiting TG than SR121903A. This difference was due to the structures of the compounds that differed in their ability to be neutralised by platelet factor 4. The antithrombotic effect of the two compounds was examined in a venous thrombosis model in rats. We observed that SanOrg123781 was more active than SR121903A and heparin.Taken together, these results indicate that the activity of oligosaccharides is greatly influenced by the global charge density of the molecule and show that SanOrg123781 is a potent and promising antithrombotic drug candidate.

The In Vitro Effects of Antithrombin III on the Activated Coagulation Time in Patients on Heparin Therapy

2000 ◽  
Vol 90 (5) ◽  
pp. 1076-1079 ◽  
Author(s):  
Jerrold H. Levy ◽  
Felix Montes ◽  
Fania Szlam ◽  
Christopher D. Hillyer
Keyword(s):  
Antithrombin Iii ◽  
Heparin Therapy ◽  
Coagulation Time ◽  
In Vitro Effects ◽  
Activated Coagulation Time
Sign in / Sign up

Export Citation Format

Share Document