Platelet Adhesion to Collagen is Inhibited by 5’ -Adenosine Diphosphate but Unaffected by Cell Shape

1979 ◽  
Author(s):  
F.A. Meyer ◽  
Z. Weisman ◽  
M. M. Frojmovic
Keyword(s):  
Cell Shape ◽  
Platelet Adhesion ◽  
Shape Change ◽  
Adenosine Diphosphate ◽  
Surface Shape ◽  
Platelet Surface ◽  
Lag Period ◽  
Per Se ◽  
Platelet Shape ◽  
Do So

The effect of ADP on the adhesion of rabbit platelets to collagen from unstirred suspensions has been investigated. Reduced binding was seen at ADP concentrations sufficient for platelets in PRP suspensions to undergo shape change (>10-8M). However, shape change per se was not involved. The time dependence of the effect of ADP on platelet shape and on platelet adhesion did not correlate. Also reduced adhesion still occurred if shape change was prevented e.g. by treatment with 1 µM PGE1 or with fixatives. Washed platelet preparations in spite of being fully shape-changed also adhered less well in the presence of ADP. As expected platelets whose shape was changed without ADP being involved, e.g. by a cold exposure treatment, displayed normal binding to collagen.ADP binding to the platelet per se is not sufficient, since reduced adhesion to collagen is seen only some time after binding has taken place. Also AMP blocked the effect of ADP on platelet adhesion if added before but not after ADP. The time dependent event that occurs is likely to be local since reduced platelet adhesion was seen with fixed platelets. It is unlikely to result from the conversion of ADP to ATP. Although ATP does inhibit adhesion, it does so only at much higher concentrations and then only after a lag period similar to that seen with ADP.Our findings imply that some of the agents reported to reduce platelet adhesion to collagen may do so by causing ADP to be released from the platelet. Surface shape and chemistry

Platelet Adhesion to Collagen Is Inhibited by Adenosine Diphosphate but Unaffected by Cell Shape

1981 ◽  
Vol 46 (02) ◽  
pp. 515-520 ◽  
Author(s):  
F A Meyer ◽  
Z Weisman ◽  
M M Frojmovic
Keyword(s):  
Binding Sites ◽  
Cell Shape ◽  
Platelet Adhesion ◽  
Shape Change ◽  
Adenosine Diphosphate ◽  
Time Dependent ◽  
Rabbit Platelets ◽  
Normal Adhesion ◽  
Per Se

SummaryThe effect of limited platelet activation, in the absence of aggregation, on the subsequent ability of rabbit platelets to adhere to collagen was studied in vitro. ADP at concentrations that initiate shape change (>0.01. μM) reduce platelet adhesion. Shape change per se however, was not responsible since the time-dependence of the effect of ADP on shape change and adhesion is different and ADP induces reduced adhesion even when shape change is prevented with PGE1 or fixatives. Platelets shape changed without ADP addition, e. g. by chilling or by low ethanol concentrations, display normal adhesion to collagenIt appears likely that upon binding to the platelet ADP induces a time-dependent alteration in the membrane, akin to refractoriness, that influences binding sites for collagen. The effect of ADP can be blocked by prior addition of AMP but not if the additions are reversed. The implications of the present findings for platelet adhesion studies are discussed.

scholarly journals Effect of aspirin on platelet-von Willebrand factor surface expression on thrombin and ADP-stimulated platelets

Blood ◽  
1989 ◽  
Vol 74 (6) ◽  
pp. 2016-2021 ◽  
Author(s):  
RI Parker ◽  
HR Gralnick
Keyword(s):  
Von Willebrand Factor ◽  
Shape Change ◽  
Adenosine Diphosphate ◽  
Surface Expression ◽  
Platelet Surface ◽  
Granule Secretion ◽  
Von Willebrand ◽  
Willebrand Factor ◽  
Platelet Shape ◽  
Stimulation Of

Abstract Platelets contain a pool of endogenous platelet-von Willebrand factor (vWF) that becomes expressed on the platelet surface when platelets are stimulated by a variety of agonists. Maximal platelet-vWF expression occurs in concert with platelet alpha-granule secretion. Aspirin (ASA) is known to impair platelet activation and alpha-granule secretion by irreversible inhibition of platelet cyclo-oxygenase. We studied native and ASA-treated platelets for their ability to mobilize and to express platelet-vWF in response to adenosine diphosphate (ADP) or thrombin. We found that each agonist was effective in promoting increased platelet- vWF surface expression on native and ASA-treated platelets. ASA-treated platelets responded identically to native platelets to low (0.01 U/mL) and high (1.0 U/mL) concentrations of thrombin, while the ADP-induced increase in ASA-treated platelets was only 50% to 60% of that for control platelets. Measurement of secreted platelet-vWF and beta- thromboglobulin indicated that the increase seen with ADP was largely independent of alpha-granule secretion. Using monoclonal antibodies (MoAbs) against the platelet glycoproteins (GP) IIb/IIIa and Ib (MoAbs 10E5 and 6D1, respectively), we demonstrated that the ADP-induced increase in platelet-vWF expression on control platelets primarily involved the binding of secreted platelet-vWF to the platelet GPIIb/IIIa. In contrast, the increase in platelet-vWF that occurred following ADP stimulation of ASA-treated platelets was largely insensitive to GPIIb/IIIa blockade. No effect of GPIb blockade in platelet-vWf expression was noted for either control or ASA-treated platelets. When platelet shape change was prevented by the addition of cytochalasin D, ADP-induced platelet-vWf surface expression on ASA- treated platelets was reduced by more than 80%. Our data indicate that platelets in which the cyclooxygenase pathway is blocked by the action of aspirin can increase surface expression of platelet-vWf as a consequence of platelet shape change. We speculate that this process exposes platelet-vWf bound to GPIIb/IIIa, or possibly GPIb, within the surface connected canalicular system.

scholarly journals Effect of aspirin on platelet-von Willebrand factor surface expression on thrombin and ADP-stimulated platelets

Blood ◽  
1989 ◽  
Vol 74 (6) ◽  
pp. 2016-2021
Author(s):  
RI Parker ◽  
HR Gralnick
Keyword(s):  
Von Willebrand Factor ◽  
Shape Change ◽  
Adenosine Diphosphate ◽  
Surface Expression ◽  
Platelet Surface ◽  
Granule Secretion ◽  
Von Willebrand ◽  
Willebrand Factor ◽  
Platelet Shape ◽  
Stimulation Of

Platelets contain a pool of endogenous platelet-von Willebrand factor (vWF) that becomes expressed on the platelet surface when platelets are stimulated by a variety of agonists. Maximal platelet-vWF expression occurs in concert with platelet alpha-granule secretion. Aspirin (ASA) is known to impair platelet activation and alpha-granule secretion by irreversible inhibition of platelet cyclo-oxygenase. We studied native and ASA-treated platelets for their ability to mobilize and to express platelet-vWF in response to adenosine diphosphate (ADP) or thrombin. We found that each agonist was effective in promoting increased platelet- vWF surface expression on native and ASA-treated platelets. ASA-treated platelets responded identically to native platelets to low (0.01 U/mL) and high (1.0 U/mL) concentrations of thrombin, while the ADP-induced increase in ASA-treated platelets was only 50% to 60% of that for control platelets. Measurement of secreted platelet-vWF and beta- thromboglobulin indicated that the increase seen with ADP was largely independent of alpha-granule secretion. Using monoclonal antibodies (MoAbs) against the platelet glycoproteins (GP) IIb/IIIa and Ib (MoAbs 10E5 and 6D1, respectively), we demonstrated that the ADP-induced increase in platelet-vWF expression on control platelets primarily involved the binding of secreted platelet-vWF to the platelet GPIIb/IIIa. In contrast, the increase in platelet-vWF that occurred following ADP stimulation of ASA-treated platelets was largely insensitive to GPIIb/IIIa blockade. No effect of GPIb blockade in platelet-vWf expression was noted for either control or ASA-treated platelets. When platelet shape change was prevented by the addition of cytochalasin D, ADP-induced platelet-vWf surface expression on ASA- treated platelets was reduced by more than 80%. Our data indicate that platelets in which the cyclooxygenase pathway is blocked by the action of aspirin can increase surface expression of platelet-vWf as a consequence of platelet shape change. We speculate that this process exposes platelet-vWf bound to GPIIb/IIIa, or possibly GPIb, within the surface connected canalicular system.

Adenosine Diphosphate (ADP)-Induced ⍺-Granules Release from Platelets of Native Whole Blood Is Reduced by Ticlopidine but Not by Aspirin or Dipyridamole

1986 ◽  
Vol 56 (02) ◽  
pp. 147-150 ◽  
Author(s):  
V Pengo ◽  
M Boschello ◽  
A Marzari ◽  
M Baca ◽  
L Schivazappa ◽  
...  
Keyword(s):  
Whole Blood ◽  
Light Transmission ◽  
Ex Vivo ◽  
Early Stage ◽  
Shape Change ◽  
Adenosine Diphosphate ◽  
Dose Dependent ◽  
Plateletderived Growth Factor ◽  
Platelet Shape

SummaryA brief contact between native whole blood and ADP promotes a dose-dependent release of platelet a-granules without a fall in the platelet number. We assessed the “ex vivo” effect of three widely used antiplatelet drugs, aspirin dipyridamole and ticlopidine, on this system. Aspirin (a single 800 mg dose) and dipyridamole (300 mg/die for four days) had no effect, while ticlopidine (500 mg/die for four days) significantly reduced the a-granules release for an ADP stimulation of 0.4 (p <0.02), 1.2 (p <0.01) and 2 pM (p <0.01). No drug, however, completeley inhibits this early stage of platelet activation. The platelet release of α-granules may be related to platelet shape change of the light transmission aggregometer and may be important “in vivo” by enhancing platelet adhesiveness and by liberating the plateletderived growth factor.

scholarly journals Inhibition of collagen-induced platelet activation by 5'-p- fluorosulfonylbenzoyl adenosine: evidence for an adenosine diphosphate requirement and synergistic influence of prostaglandin endoperoxides

Blood ◽  
1986 ◽  
Vol 68 (2) ◽  
pp. 565-570 ◽  
Author(s):  
RW Colman ◽  
WR Figures ◽  
LM Scearce ◽  
AM Strimpler ◽  
FX Zhou ◽  
...  
Keyword(s):  
Platelet Activation ◽  
Shape Change ◽  
Thromboxane A2 ◽  
Adenosine Diphosphate ◽  
Platelet Surface ◽  
Prostaglandin Endoperoxide ◽  
Fibrinogen Binding ◽  
Low Concentrations ◽  
Absolute Requirement

Abstract The relative roles of platelet autacoids such as adenosine diphosphate (ADP), prostaglandin endoperoxides, and thromboxane A2 (TXA2) in collagen-induced platelet activation are not fully understood. We reexamined this relationship using the ADP affinity analogue, 5'-p- fluorosulfonylbenzoyl adenosine (FSBA), which covalently modifies a receptor for ADP on the platelet surface, thereby inhibiting ADP- induced platelet activation. Collagen-induced shape change, aggregation, and fibrinogen binding were each fully inhibited under conditions in which FSBA is covalently incorporated and could not be overcome by raising the collagen used to supramaximal concentrations. In contrast, TXA2 synthesis stimulated by collagen under conditions that produced maximum aggregation was only minimally inhibited by FSBA. Since covalent incorporation of FSBA has been previously shown to specifically inhibit ADP-induced activation of platelets, the present study supports the contention that ADP is required for collagen-induced platelet activation. Under similar conditions, indomethacin, an inhibitor of cyclooxygenase, inhibited collagen-induced shape change, indicating that endoperoxides and/or TXA2 also play a role in this response. Shape change induced by low concentrations (10 nmol/L) of the stable prostaglandin endoperoxide, azo-PGH2, was also inhibited by FSBA. These observations indicate a role for ADP in responses elicited by low concentrations of endoperoxides. However, at higher concentrations of azo-PGH2 (100 nmol/L), inhibition by FSBA could be overcome. Thus, the effect of collagen apparently has an absolute requirement for ADP for aggregation and fibrinogen binding and for both ADP and prostaglandins for shape change. Aggregation and fibrinogen binding induced by prostaglandin endoperoxides also required ADP as a mediator, but ADP is not absolutely required at high endoperoxide concentration to induce shape change.

LUMI-AGGREGOMETER STUDIES OF THE INITIAL ATP-SECRETION FROM COLLAGEN-ADHERENT PLATELETS

1987 ◽  
Author(s):  
R Malmgren
Keyword(s):  
Platelet Adhesion ◽  
Rank Order ◽  
Shape Change ◽  
Dense Granule ◽  
Dependent Manner ◽  
Equal Degree ◽  
Atp Secretion ◽  
Ic50 Values ◽  
Dose Dependent ◽  
Platelet Shape

We have earlier, with the use of a lumi-aggregometer and sub-aggregating doses of collagen (0.2-0.8 ug/ml PRP), been able to detect the initial, aspirin-insensitive secretion of ATP from the collagen-adherent platelets, and to correlate this secretion to the doses of collagen, and onset and degree of subsequent shape change of non-adherent platelets (Malmgren, Thromb Res 4:445, 1986). The present study shows, that 200 ATU of hirudin,which reduced near-maximal aggregation and ATP-secretion induced by high collagen doses (2.5 ug/ml PRP) from 3.35 ± 0.2 uM to 2.85 ± 0.1 uM, did neither reduce the secreted amount of ATP that were 82.5 ± 15 nM in control samples and 90 ± 27.5 nM in hirudin-treated samples, nor reduce platelet shape change when platelets were challenged with 0.31 ug collagen /ml PRP. (200 ATU hirudin completely abolished an equal degree of platelet shape change induced by 0.01 U thrombin). Assuming that 3 % of the platelets in PRP were actually adhering to the collagen fibrils, the secreted amount corresponds to 14.6 ±0.04 pmoles ATP/106adheringplatelets, amounts which closely represented 100 % of their dense granule content. The finding confirms that hirudin does not inhibit platelet adhesion and also indicates, that thrombin-mediated activation of secretory pathways appears not to be involved during the initial phase of platelet-collagen interactions.Dipyridamole (DPA) and dibutyryl cAMP (DBcAMP) inhibited ATP-secretion and platelet aggregation in a dose-dependent manner at high collagen concentrations, but only DBcAMP caused a dose-dependent reduction of ATP secretion (IC50 =10-4 M) induced by sub-aggregating doses of collagen. DPA was devoid of effect in this respect and thus did not inhibit platelet adhesion.Yohimbine, dihydroergotamine and phentolamine reduced ATP-secretion induced by sub-aggregating collagen doses in the mentioned rank order of potency, and with IC50 values in the micromolar range. Ketanserin, ritanserin and propranolol were devoid of effect. The findings suggest that the initial collagen-plate-let interaction involve alfareceptor-mediated mechanisms that may encompass adhesion, while DBcAMP probably interacts with secretory mechanisms connected to phosphatidylinositol turnover.

scholarly journals GPR56/ADGRG1 is a platelet collagen-responsive GPCR and hemostatic sensor of shear force

2020 ◽  
Vol 117 (45) ◽  
pp. 28275-28286 ◽  
Author(s):  
Jennifer Yeung ◽  
Reheman Adili ◽  
Emily N. Stringham ◽  
Rong Luo ◽  
Alexander Vizurraga ◽  
...  
Keyword(s):  
Blood Flow ◽  
G Protein ◽  
Shear Force ◽  
Platelet Adhesion ◽  
Shape Change ◽  
Blood Perfusion ◽  
Perfusion Studies ◽  
Platelet Receptor ◽  
Plug Formation ◽  
Platelet Shape

Circulating platelets roll along exposed collagen at vessel injury sites and respond with filipodia protrusion, shape change, and surface area expansion to facilitate platelet adhesion and plug formation. Various glycoproteins were considered to be both collagen responders and mediators of platelet adhesion, yet the signaling kinetics emanating from these receptors do not fully account for the rapid platelet cytoskeletal changes that occur in blood flow. We found the free N-terminal fragment of the adhesion G protein-coupled receptor (GPCR) GPR56 in human plasma and report that GPR56 is the platelet receptor that transduces signals from collagen and blood flow-induced shear force to activate G protein 13 signaling for platelet shape change.Gpr56−/−mice have prolonged bleeding, defective platelet plug formation, and delayed thrombotic occlusion. Human and mouse blood perfusion studies demonstrated GPR56 and shear-force dependence of platelet adhesion to immobilized collagen. Our work places GPR56 as an initial collagen responder and shear-force transducer that is essential for platelet shape change during hemostasis.

scholarly journals Changes in phosphatidylinositol-4,5-bisphosphate 10 seconds after stimulation of washed rabbit platelets with ADP

Blood ◽  
1982 ◽  
Vol 60 (6) ◽  
pp. 1247-1250
Author(s):  
JD Vickers ◽  
RL Kinlough-Rathbone ◽  
JF Mustard
Keyword(s):  
Shape Change ◽  
Adenosine Diphosphate ◽  
Cellular Responses ◽  
Release Reaction ◽  
Rabbit Platelets ◽  
Induced Aggregation ◽  
Platelet Shape ◽  
Stimulation Of

Adenosine diphosphate (ADP) induced aggregation of rabbit platelets, without the release reaction, causes a significant decrease (7%) in the amount of phosphatidylinositol-4,5-bisphosphate (PIP2) at 10 sec and at 60 sec (11%). In platelets prelabeled with 32P-phosphate, this decrease in PIP2 is associated with a decrease in PIP2 radioactivity, which is significant at 50 sec. The decrease in PIP2 is sufficient to mobilize about 0.18 nmole Ca2+/10(9) platelets. In view of the key role played by Ca2+ in ADP-induced platelet shape change and aggregation, this evidence is compatible with the hypothesis that changes in PIP2 can be a source of calcium for cellular responses to agonists.

Differential Inhibition of the Platelet Activation Sequence: Shape Change, Micro- and Macro-Aggregation, by a Stable Prostacyclin Analogue (lloprost)

1988 ◽  
Vol 59 (02) ◽  
pp. 323-328 ◽  
Author(s):  
L G Pedvis ◽  
T Wong ◽  
M M Frojmovic
Keyword(s):  
Shape Change ◽  
Adenosine Diphosphate ◽  
Differential Inhibition ◽  
Dose Dependency ◽  
Response Curves ◽  
Healthy Human ◽  
Rates Of Change ◽  
Electronic Platelet Counting ◽  
Platelet Shape ◽  
Activation Sequence

SummaryThe relative sensitivities of adenosine diphosphate (ADP)-induced activation, and of prostaglandin-mediated inhibition, were determined for rates of platelet shape change (SC [Vs]), early platelet recruitment measured by electronic platelet counting (PA [PA3]), and turbidometrically-measured aggregation (TA[Va]). Studies were performed in stirred citrated platelet-richplasma from 9 healthy human donors. The [ADP]1/2, ([ADP]giving half maximal rate) was determined for the sequence of activation steps: unactivated platelets → SC → PA → TA. Distinct ADP sensitivities were obtained from log dose-responsestudies, with a relative dose dependency for rates of change in the order of [ADP]1/2 TA > [ADP]1/2 PA > [ADP]1/2 SC of ~4:3:1.Differential inhibition of the above activation scheme was evalu-ated from log dose-response curves for lloprost (ZK 36374), astable carbacyclin analogue of prostacyclin (PGI2), with greaterpotency than PGI2 for the same platelet receptors. IC50 valuescorresponding to lloprost concentrations causing 50% inhibitionof rates of TA (Va), PA (PA3) and SC (Vs) were found in therelative ratios of 1: ~3: ~5, when measured at a common ADPconcentration for all three parameters, or 1: ~2: ~3 when deter-mined at respective [ADP]1/2 values for each parameter. Thus, about 3-5 times more lloprost is required to respectively inhibitthe rates of shape change (Vs) and early platelet recruitment(PA3), than that needed to inhibit the rate of turbidometrically-measured aggregation (Va).

scholarly journals Changes in cytosolic calcium concentrations and cell morphology in single platelets adhered to fibrinogen-coated surface under flow

Blood ◽  
1996 ◽  
Vol 87 (9) ◽  
pp. 3775-3782 ◽  
Author(s):  
CJ Jen ◽  
HI Chen ◽  
KC Lai ◽  
S Usami
Keyword(s):  
Platelet Adhesion ◽  
Morphological Changes ◽  
Shape Change ◽  
Cytosolic Calcium ◽  
Lag Time ◽  
Flow Chamber ◽  
Platelet Surface ◽  
Ratio Imaging ◽  
Coated Surface ◽  
Normal Shape

Changes in intracellular calcium concentration [Ca2+]i of fura-2-loaded human platelet during its adhesion to a fibrinogen-coated surface were studied, using a flow chamber mounted on an epifluorescence microscope equipped with digital-ratio imaging. Adherent platelets were individually mapped under a scanning electron microscope to establish the possible correlation between adhesion-associated shape alterations and [Ca2+]i changes. We found that 1) there was no immediate [Ca2+]i elevation on platelet adhesion; 2) [Ca2+]i changes varied drastically platelets with a lag time ranging 10 to 200 s, averaging about 1 minute; 3) the pattern of [Ca2+]i changes varied drastically among individual adherent platelets; 4) the degree of [Ca2+]i elevation appeared to correlate with the extent of morphology change, with the vast majority ( > 90%) of spread platelets showed detectable [Ca2+]i changes; 5) neither morphological nor [Ca2+]i changes correlated with the lag time; 6) platelets treated with dimethyl-BAPTA (15 mumol/L) underwent normal shape change without [Ca2+]i elevation; 7) cytochalasin D (10 mumol/L) inhibited both shape change and [Ca2+]i elevation; 8) colchicine (1 mmol/L) was ineffective in both regards. We conclude that although platelet adhesion-associated shape changes may be accompanied with heterogeneous [Ca2+]i changes that are microfilament-dependent, [Ca2+]i changes do not happen immediately after platelet-surface contact and they are not required for adherent platelets to undergo postcontact morphological changes.

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