scholarly journals Potassium uptake and release by human blood platelets

Blood ◽  
1976 ◽  
Vol 48 (2) ◽  
pp. 185-197
Author(s):  
JS Wiley ◽  
J Kuchibhotla ◽  
CC Shaller ◽  
RW Colman
Keyword(s):  
Time Course ◽  
Specific Activity ◽  
Blood Platelets ◽  
Gel Filtration ◽  
Lactic Dehydrogenase ◽  
Human Platelets ◽  
First Order Kinetics ◽  
A Minor ◽  
Human Blood Platelets

Thrombin is known to reduce the K+ content of human platelets, but the subcellular origin of the lost K+ is not known. The effect of aggregating agents on K+ release was studied in platelets labeled in plasma by preincubation with 42KCI. Platelets were separated from plasma by gel filtration through Sepharose 2B equilibrated with K+ - free Tyrode's buffer. Platelet K+ was 116nEq/10(8) platelets, of which 23% was found to be extracellular immediately after gel filtration. K+ influx was 65 nEq/10(8) platelets/hr at pH 7.5 and was more rapid at pH 7.9. About 70% of cell K+ exchanged with plasma in 4 hr with first- order kinetics, while a minor fraction of about 30% exchanged with a slower time course. This slowly exchanging fraction of platelet K+ was thought to arise from heterogeneity in the platelet population. Epinephrine and ADP aggregated gel-filtered platelets and released serotonin, but with loss of only 5%-10% of cell K+ and no beta- glucuronidase. In contrast, thrombin released up to 30% of platelet K+, whether aggregation occurred or was prevented by not stirring the cells. The specific activity of K+ released by all aggregating agents was identical to the specific activity of total platelet K+. Thrombin (0.01–0.2 NIH U/ml) released serotonin and also beta-glucuronidase (an enzyme of the alpha-granule), and there was a linear relation between release of K+ and this enzyme (r = 0.88). No lysis of platelets occurred, since lactic dehydrogenase was not detected. Pretreatment of platelets with aspirin in vitro inhibited thrombin-induced release of serotonin but had no effect on the loss of K+ or beta-glucuronidase. In contrast, the ingestion of aspirin by mouth inhibited the release of serotonin, beta-glucuronidase, and K+ by thrombin. The data suggested that the K+ loss induced by thrombin was primarily derived from release of alpha-granules and that these organelles contained about 20% of the total platelet K+ in a freely exchangeable and nonsequestered state.

scholarly journals Potassium uptake and release by human blood platelets

Blood ◽  
1976 ◽  
Vol 48 (2) ◽  
pp. 185-197 ◽  
Author(s):  
JS Wiley ◽  
J Kuchibhotla ◽  
CC Shaller ◽  
RW Colman
Keyword(s):  
Time Course ◽  
Specific Activity ◽  
Blood Platelets ◽  
Gel Filtration ◽  
Lactic Dehydrogenase ◽  
Human Platelets ◽  
First Order Kinetics ◽  
A Minor ◽  
Human Blood Platelets

Abstract Thrombin is known to reduce the K+ content of human platelets, but the subcellular origin of the lost K+ is not known. The effect of aggregating agents on K+ release was studied in platelets labeled in plasma by preincubation with 42KCI. Platelets were separated from plasma by gel filtration through Sepharose 2B equilibrated with K+ - free Tyrode's buffer. Platelet K+ was 116nEq/10(8) platelets, of which 23% was found to be extracellular immediately after gel filtration. K+ influx was 65 nEq/10(8) platelets/hr at pH 7.5 and was more rapid at pH 7.9. About 70% of cell K+ exchanged with plasma in 4 hr with first- order kinetics, while a minor fraction of about 30% exchanged with a slower time course. This slowly exchanging fraction of platelet K+ was thought to arise from heterogeneity in the platelet population. Epinephrine and ADP aggregated gel-filtered platelets and released serotonin, but with loss of only 5%-10% of cell K+ and no beta- glucuronidase. In contrast, thrombin released up to 30% of platelet K+, whether aggregation occurred or was prevented by not stirring the cells. The specific activity of K+ released by all aggregating agents was identical to the specific activity of total platelet K+. Thrombin (0.01–0.2 NIH U/ml) released serotonin and also beta-glucuronidase (an enzyme of the alpha-granule), and there was a linear relation between release of K+ and this enzyme (r = 0.88). No lysis of platelets occurred, since lactic dehydrogenase was not detected. Pretreatment of platelets with aspirin in vitro inhibited thrombin-induced release of serotonin but had no effect on the loss of K+ or beta-glucuronidase. In contrast, the ingestion of aspirin by mouth inhibited the release of serotonin, beta-glucuronidase, and K+ by thrombin. The data suggested that the K+ loss induced by thrombin was primarily derived from release of alpha-granules and that these organelles contained about 20% of the total platelet K+ in a freely exchangeable and nonsequestered state.

Interaction of β2-Glycoprotein-I with Human Blood Platelets: Influence Upon the ADP-Induced Aggregation

1985 ◽  
Vol 54 (02) ◽  
pp. 397-401 ◽  
Author(s):  
Johannes Nimpf ◽  
Helmut Wurm ◽  
Gerhard M Kostner
Keyword(s):  
Binding Sites ◽  
Specific Binding ◽  
Blood Platelets ◽  
Gel Filtration ◽  
Human Platelets ◽  
Glycoprotein I ◽  
Unspecific Binding ◽  
Induced Aggregation ◽  
Human Blood Platelets

SummaryThe interaction of β2-glycoprotein-I (β2-G-I), a plasma constituent of unknown function, with blood platelets was studied. The following results were obtained: 1) β2-G-I binds to washed human platelets isolated by centrifugation (WP) at one kind of specific, saturable binding sites. The dissociation constant was found to be approx. 1 × 10−6M.2) In the presence of physiological concentrations of Ca++ (2.5 mM), this specific binding is markedly reduced. Unspecific binding of β2-G-I to platelets, however, is not influenced by Ca++.3) Platelets prepared by gel filtration (GFP), differing in their in vitro aggregability from WP, exhibit no specific binding of β2-G-I. Binding to GFP is also not induced by activation with thrombin, collagen or ADP.4) β2-G-I causes significant alteration of the ADP-induced aggregation of GFP. Aggregation induced by thrombin, collagen, arachidonic acid or PAF-acether, however is not altered by β2G-I.It is suggested, that pelleting during centrifugation causes irreversible rearrangements in the membrane of platelets.

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 Separation of Human Blood Platelets from Factor VIII (Von Willebrand’s Factor) by Combined Albumin Gradient-Gel Filtration Method

1977 ◽  
Author(s):  
S. Timmons ◽  
J. Hawiger
Keyword(s):  
Factor Viii ◽  
Human Blood ◽  
Blood Platelets ◽  
Gel Filtration ◽  
Human Platelets ◽  
Small Samples ◽  
Filtration Method ◽  
Ethanesulfonic Acid ◽  
Von Willebrand’S Factor

Currently used gel filtration methods were investigated in order to obtain a system which would effectively separate platelets from plasma proteins, such as Factor VIII/von Willebrand’s Factor (FVIII/vWF), in relatively small samples of human blood which are not amenable to repeated centrifugation. BioGel A150, which has a higher exclusion limit than the presently used Sepharose 2B, was found to be equally effective for preparing gel-filtered platelets. However, it did not completely separate the FVIII/vWF as judged by ristocetin-induced platelet aggregation. Therefore, a stepwise albumin gradient was employed as a preceeding step to gel filtration on BioGel A150. Platelets obtained by this modification were not responsive to ristocetin unless human plasma, as a source of FVIII/vWF, was added. Tyrode buffer, which shows variation in pH due to changes in pCO2, was replaced by the more stable zwitterionic buffer containing N-2-hydroxyethylpiperazine-N’2-ethanesulfonic acid (HEPES) pH 7.4. The need for control of CO2 was thereby obviated, reactivity of platelets in vitro was maintained, and their functional life span was extended from 1 to 2 hours. This modification of existing methods allows efficient separation of human platelets from FVIII/vWF and from other plasma macromolecules in relatively small samples of blood with preservation of the functional integrity of obtained platelet preparations.

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

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.

The Effect of Phospholipase C on Platelet Factor 3 in Human Blood Platelets

1977 ◽  
Vol 37 (01) ◽  
pp. 029-035 ◽  
Author(s):  
A-B Otnaess ◽  
H Prydz
Keyword(s):  
Phospholipase C ◽  
Human Blood ◽  
Blood Platelets ◽  
Gel Filtration ◽  
Human Platelets ◽  
Small Reduction ◽  
Platelet Factor ◽  
Human Blood Platelets ◽  
External Attack

SummaryIntact human platelets isolated by gel filtration have been treated with purified phospholipase C. The effect of the enzyme on available and total platelet factor 3 has been tested.The available procoagulant platelet factor 3 was very low. A further small reduction was observed after incubation with phospholipase C when the enzyme was washed away before testing.External attack on platelets by phospholipase C led to a marked inactivation of total platelet factor 3.

Immune Reactions of Human Blood Platelets

1968 ◽  
Vol 20 (03/04) ◽  
pp. 336-344 ◽  
Author(s):  
Ch Mueller-Eckhardt ◽  
E. F Lüscher
Keyword(s):  
Adenine Nucleotides ◽  
Blood Platelets ◽  
Fibrin Clot ◽  
Human Platelets ◽  
The Other ◽  
Buffer Solution ◽  
Plasma Fractions ◽  
Mediator Substances ◽  
Human Blood Platelets

SummaryThe effect on human platelets of 2 endotoxin preparations (one had known Shwartzman-activity in rabbits, the other was not tested for its biological activity) was investigated in vitro. The following results were found:1. Endotoxin has no effect on washed human platelets suspended in isotonic, plasmafree buffer solution.2. Aggregation or release of adenine nucleotides from human platelets by endotoxin does also not occur if the platelets are suspended in coagulable, complement active, pooled human plasma or plasma fractions.3. Platelets pretreated with α-chymotrypsin do not show aggregation or release of nucleotides by endotoxin.4. The ability of human platelets to retract a fibrin clot is not disturbed by endotoxin. This excludes a functional platelet injury by endotoxin not detectable by aggregation or nucleotide release.5. There is no evidence for the assumption that the effect of endotoxin on platelets is transmitted by yet hypothetical, platelet-damaging mediator substances from leukocytes.6. These results suggest that an immunological injury of platelets by endotoxin comparable with the effect of immune complexes or aggregated gammaglobulin is highly improbable.

scholarly journals Interaction of Human Platelets with Subndotrelium: Implications for Measurement of Defects in Platelet Function

1977 ◽  
Author(s):  
V.T. Turitto ◽  
H.J. Weiss ◽  
D.S. Cohen
Keyword(s):  
Platelet Reactivity ◽  
Blood Platelets ◽  
Human Platelets ◽  
Shear Rates ◽  
High Shear Rates ◽  
Contact Adhesion ◽  
Human Blood Platelets ◽  
Low Shear ◽  
Platelet Transport

An in Vitro perfusion technique introduced by Baumgartner has been used to investigate the interaction of human blood platelets with subendothelium of rabbit aortas. Platelet contact, adhesion (spreading) and the formation of ndcxothrombi were measured directly by use of a morphometric technique for a variety of exposure times (1 to 40 min) and a physiological range of flow rates (shear rates varying from 50 to 830 sec-1). A theory accounting for platelet transport through the blood and the platelet reactivity at the vessel surface Indicated platelet transport to be the controlling influence on platelet attachment. Under low shear conditions platelet attachment is unaltered by moderate changes in platelet reactivity. The results suggest that high shear rates (greater than 800 sec-1) are necessary for a sensitive measurement of defects in platelet attachment and that experimental devices which employ low shear conditions are limited in measuring such defects.

scholarly journals Effect of heterologous antibody on human platelets

Blood ◽  
1976 ◽  
Vol 48 (1) ◽  
pp. 119-131
Author(s):  
RW Colman ◽  
AD Schreiber
Keyword(s):  
Platelet Aggregation ◽  
Human Platelet ◽  
Gel Filtration ◽  
Lactic Dehydrogenase ◽  
Human Platelets ◽  
Thrombin Inhibitors ◽  
Antiplatelet Antibody ◽  
Heterologous Antibody ◽  
Platelet Antibody

The effect of heterologous anti-human platelet antibody on human platelet function was examined in the presence and absence of whole plasma as an in vitro model for antibody-induced immune damage to cells. Heterologous IgG anti-human platelet antibody mediated platelet aggregation and released serotonin from both platelets in plasma and from platelets isolated by gel filtration and increased the availability of platelet acid phosphatase in a dose-response fashion. Anti-platelet antibody failed to release beta-glucuronidase (lysosomal enzyme marker) or cause lactic dehydrogenase loss (cytolysis). The effect of the antiplatelet antibody on platelets proceeded in the absence of complement. The active molecule in the anti-platelet antiserum was isolated in the IgG fraction and all three indi cators of platelet injury were mediated by purified monomeric IgG. Thrombin was not required for the antibody-mediated effects, as three thrombin inhibitors failed to block the reaction. EDTA was an effective inhibitor, suggesting a cation requirement; however, as little as 38 muM calcium was sufficient for effective platelet aggregation and release. The inability of acetylsalicylic acid to inhibit the effect of the antiplatelet antibody suggests that heterologous antibody (IgG) induced platelet alteration proceeds by a different mechanism than that mediated by ADP and epinephrine and does not involve endogenous platelet prostaglandin synthesis.

Effect of heterologous antibody on human platelets

Blood ◽  
1976 ◽  
Vol 48 (1) ◽  
pp. 119-131 ◽  
Author(s):  
RW Colman ◽  
AD Schreiber
Keyword(s):  
Platelet Aggregation ◽  
Human Platelet ◽  
Gel Filtration ◽  
Lactic Dehydrogenase ◽  
Human Platelets ◽  
Thrombin Inhibitors ◽  
Antiplatelet Antibody ◽  
Heterologous Antibody ◽  
Platelet Antibody

Abstract The effect of heterologous anti-human platelet antibody on human platelet function was examined in the presence and absence of whole plasma as an in vitro model for antibody-induced immune damage to cells. Heterologous IgG anti-human platelet antibody mediated platelet aggregation and released serotonin from both platelets in plasma and from platelets isolated by gel filtration and increased the availability of platelet acid phosphatase in a dose-response fashion. Anti-platelet antibody failed to release beta-glucuronidase (lysosomal enzyme marker) or cause lactic dehydrogenase loss (cytolysis). The effect of the antiplatelet antibody on platelets proceeded in the absence of complement. The active molecule in the anti-platelet antiserum was isolated in the IgG fraction and all three indi cators of platelet injury were mediated by purified monomeric IgG. Thrombin was not required for the antibody-mediated effects, as three thrombin inhibitors failed to block the reaction. EDTA was an effective inhibitor, suggesting a cation requirement; however, as little as 38 muM calcium was sufficient for effective platelet aggregation and release. The inability of acetylsalicylic acid to inhibit the effect of the antiplatelet antibody suggests that heterologous antibody (IgG) induced platelet alteration proceeds by a different mechanism than that mediated by ADP and epinephrine and does not involve endogenous platelet prostaglandin synthesis.

Sign in / Sign up

Export Citation Format

Share Document