Change in electrophoretic mobility associated with the shape change of human blood platelets

1977 ◽  
Vol 196 (1125) ◽  
pp. 471-474 ◽  
Keyword(s):  
Electrophoretic Mobility ◽  
Human Blood ◽  
Shape Change ◽  
Blood Platelets ◽  
Sialic Acids ◽  
Membrane Glycoproteins ◽  
Platelet Surface ◽  
Human Blood Platelets

All physiological pH platelets, like other cells, have an excess of negative electric charges on the surface which determine their electrophoretic mobility (Seaman & Vassar 1966; Hampton & Mitchell 1974). The greater part of these negative charges are due to sialic acids bound to membrane glycoproteins (Madoff, Ebbe & Baldini 1964). Removal of sialic acids from the platelet surface by neuraminidase diminishes the electrophoretic mobility of platelets (Bray & Alexander 1969). It has been shown recently that the rapid shape change of platelets which precedes their aggregation by ADP or 5-hydroxytryptamine is associated with an increase in sialic acids removable by neuraminidase (Motamed, Michal & Born 1976). If this increase in sialic acids were on the platelet surface which determines their electrophoretic mobility, it should show itself as an increase in that mobility. This paper shows that the mobility increases when the shape change is induced by ADP.

Influence of Blood Platelets on Fibrinolysis

1961 ◽  
Vol 6 (02) ◽  
pp. 196-214 ◽  
Author(s):  
Rudolf Holemans ◽  
Rudolf Gross
Keyword(s):  
Human Blood ◽  
Blood Platelets ◽  
Human Platelets ◽  
Bovine Blood ◽  
Platelet Surface ◽  
Inhibiting Effect ◽  
Platelet Concentration ◽  
Streptokinase Infusion ◽  
Human Plasminogen ◽  
Human Blood Platelets

Summary1. Human blood platelets contain a considerable amount of proactivator activity but no plasminogen activator activity or plasminogen. In test systems, containing streptokinase, the lysis of bovine fibrin is enhanced, depending upon the amount of platelets present.2. The platelet proactivator is completely destroyed by heating during 15 min at 70° C. Washing of platelets reduces their proactivator activity; however proactivator activity can still be found after ten washings.3. Bovine platelets do not contain proactivator activity. The similarity in the content in proactivator activity in plasma and platelets of both species, as well as the decrease of proactivator activity by washing, strongly suggests that the proactivator activity of human platelets is adsorbed on the platelet surface from the plasma.4. Both in human platelets and in bovine platelets, antifibrinolysin can be found. This factor is thermostable and is only slightly diminished by washing. The platelet antifibrinolysin seems for its larger part to be located in the platelets; only a small fraction may be adsorbed on their surface.5. The platelet antifibrinolytic activity can, depending upon the platelet concentration, be easily determined in systems containing urokinase or plasmin. Also in streptokinase-activated systems, bovine blood platelets have an inhibiting effect; human blood platelets inhibit streptokinase-induced fibrinolysis when their proactivator activity has been destroyed by heating. When streptokinase and unheated human blood platelets are tested on bovine fibrin the inhibitor effect is completely masked by the presence of proactivator.6. The clinical significance of these findings with regard to fibrinolysis occurring spontaneously or induced by streptokinase infusion, as well as their importance for the differentiation of proactivator and human plasminogen are discussed.

Effect of Glass Contact on the Electrophoretic Mobility of Human Blood Platelets

Nature ◽  
1966 ◽  
Vol 209 (5022) ◽  
pp. 470-472 ◽  
Author(s):  
J. R. HAMPTON ◽  
J. R. A. MITCHELL
Keyword(s):  
Electrophoretic Mobility ◽  
Human Blood ◽  
Blood Platelets ◽  
Human Blood Platelets

Freeze-Fracture Studies of Human Blood Platelets Activated by Thrombin Using Rapid Freezing

1985 ◽  
Vol 54 (03) ◽  
pp. 574-578 ◽  
Author(s):  
Hans Hols ◽  
Jan J Sixma ◽  
J Leunissen-Bijvelt ◽  
Arie Verkley
Keyword(s):  
Human Blood ◽  
Shape Change ◽  
Blood Platelets ◽  
Secretory Granules ◽  
Freeze Fracture ◽  
Rapid Freezing ◽  
Freeze Fracturing ◽  
Morphological Alterations ◽  
Thrombin Activation ◽  
Human Blood Platelets

SummaryIn this study the influence of thrombin activation on human blood platelets has been followed by freeze-fracturing electron microscopy using rapid freezing in order to catch the initial changes in shape and the morphological alterations during the process of exocytosis of secretory granules. We found that isolation of the platelets by itself leads to some degree of shape change, which made it impossible to study the resting discoid platelet by rapid freezing.Activation of the platelets by thrombin induced dilation of the “surface connecting system (SCS)” with formation of large vacuoles as a result of fusion of the secretory granules with SCS. No intermediary fusion stages or structures were observed even using rapid freezing. Volcano-like protrusions and the corresponding complementary pits were seen at the SCS. These structures were interpreted by us as fractures through protoplasmic channels crossing the SCS. These channels originate during the swelling of the SCS as a result of the fusion of secretory granules with the SCS.

scholarly journals Heterogeneity in filamentous actin content among individual human blood platelets

Blood ◽  
1992 ◽  
Vol 79 (4) ◽  
pp. 920-927
Author(s):  
A Oda ◽  
JF Daley ◽  
C Cabral ◽  
JH Kang ◽  
M Smith ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
Fluorescent Probe ◽  
Human Blood ◽  
Actin Polymerization ◽  
Shape Change ◽  
Blood Platelets ◽  
Significant Loss ◽  
Free Calcium ◽  
Filamentous Actin ◽  
Human Blood Platelets

Abstract The content of filamentous actin in individual platelets was measured by flow cytometry, using a fluorescent probe specific for filamentous actin (F-actin), 7-nitrobenz-2-oxa-1,3-phallacidin (NBD-phallacidin). NBD-phallacidin binding to fixed platelets was specific in that either pretreatment of platelets with unlabeled phallacidin or absorption of NBD-phallacidin by rabbit skeletal F-actin, but not globular actin (G- actin), resulted in a significant loss in the bound fluorescent probe. Mean NBD-phallacidin binding to fixed platelets varied with the agonist and paralleled the changes in F-actin reported with the DNAse I inhibition assay. (1) NBD-phallacidin binding increased with stimulation by ADP, U46619 (a prostaglandin H2 analogue), or collagen and paralleled shape change. (2) Epinephrine did not increase NBD- phallacidin binding. (3) Platelets treated at 4 degrees C contained more F-actin than did platelets kept at 37 degrees C. (4) Cytochalasin D (10 mumol/L) inhibited the increase of phallacidin binding to individual platelets stimulated by either ADP or U46619. In measurements of cytosolic free calcium concentration ([Ca2+]i) by flow cytometry in Indo-1-loaded platelets, ADP's dose-response for actin polymerization was similar to that for calcium mobilization. As shown by flow cytometry, a tail population that had a minimal increase in F- actin upon stimulation with ADP or U46619 also contained the platelets with the least forward and right angle light scattering, which are functions of platelet size and shape. When platelets treated with NBD- phallacidin were incubated with S12-murine monoclonal antibody (a marker of alpha-granule secretion detected by phycoerythrin-conjugated antimouse IgG second antibody), phallacidin fluorescence paralleled S12 binding. Thus, human blood platelets are heterogeneous in regard to actin polymerization at rest and in association with platelet activation; different degrees of phallacidin binding may identify functionally different platelet populations.

scholarly journals Heterogeneity in filamentous actin content among individual human blood platelets

Blood ◽  
1992 ◽  
Vol 79 (4) ◽  
pp. 920-927 ◽  
Author(s):  
A Oda ◽  
JF Daley ◽  
C Cabral ◽  
JH Kang ◽  
M Smith ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
Fluorescent Probe ◽  
Human Blood ◽  
Actin Polymerization ◽  
Shape Change ◽  
Blood Platelets ◽  
Significant Loss ◽  
Free Calcium ◽  
Filamentous Actin ◽  
Human Blood Platelets

The content of filamentous actin in individual platelets was measured by flow cytometry, using a fluorescent probe specific for filamentous actin (F-actin), 7-nitrobenz-2-oxa-1,3-phallacidin (NBD-phallacidin). NBD-phallacidin binding to fixed platelets was specific in that either pretreatment of platelets with unlabeled phallacidin or absorption of NBD-phallacidin by rabbit skeletal F-actin, but not globular actin (G- actin), resulted in a significant loss in the bound fluorescent probe. Mean NBD-phallacidin binding to fixed platelets varied with the agonist and paralleled the changes in F-actin reported with the DNAse I inhibition assay. (1) NBD-phallacidin binding increased with stimulation by ADP, U46619 (a prostaglandin H2 analogue), or collagen and paralleled shape change. (2) Epinephrine did not increase NBD- phallacidin binding. (3) Platelets treated at 4 degrees C contained more F-actin than did platelets kept at 37 degrees C. (4) Cytochalasin D (10 mumol/L) inhibited the increase of phallacidin binding to individual platelets stimulated by either ADP or U46619. In measurements of cytosolic free calcium concentration ([Ca2+]i) by flow cytometry in Indo-1-loaded platelets, ADP's dose-response for actin polymerization was similar to that for calcium mobilization. As shown by flow cytometry, a tail population that had a minimal increase in F- actin upon stimulation with ADP or U46619 also contained the platelets with the least forward and right angle light scattering, which are functions of platelet size and shape. When platelets treated with NBD- phallacidin were incubated with S12-murine monoclonal antibody (a marker of alpha-granule secretion detected by phycoerythrin-conjugated antimouse IgG second antibody), phallacidin fluorescence paralleled S12 binding. Thus, human blood platelets are heterogeneous in regard to actin polymerization at rest and in association with platelet activation; different degrees of phallacidin binding may identify functionally different platelet populations.

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