Studies on Thrombin-Induced Platelet Agglutination

Shermer, R W; Mason, R. G.; Wagner, Robert H.; Brinkhous, K. M.

doi:10.1084/jem.114.6.905

Cited by 41 publications

(7 citation statements)

References 27 publications

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“…Divalent cations are known to influence other effects of thrombin on platelets (17) and also to affect the reaction of thrombin and plasma fibrinogen (18). The enhanced release of potassium from platelets by thrombin in the presence of divalent cation may be due to an alteration of the reaction of thrombin with platelet fibrinogen, but other possibilities exist.…”

Section: Discussionmentioning

confidence: 99%

Effects of Thrombin on the Potassium and ATP Content of Platelets *

Zieve¹,

Gamble²,

Jackson³

1964

J. Clin. Invest.

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The blood platelets have many of the characteristics of living cells including an active metabolism. As in other cells, the concentration of potassium within platelets is high in comparison to that of extracellular fluid and-is similar to that of red blood cells (1). ATP also is present in high concentration within platelets (2) and is considered to provide the energy necessary for clot retraction, a process that requires metabolically active platelets (3). Unlike other cells, platelets are uniquely susceptible to the effects of thrombin, a proteolytic enzyme formed during clotting of blood. During coagulation, the platelets undergo a complex series of morphologic and biochemical changes (4), and there is a decrease in the concentration of some of the constituents of platelets, including potassium (1) and ATP (5). The present studies were designed to investigate some of the factors that influence changes in potassium and ATP within platelets. MethodsAll glassware with which platelets had contact was coated with silicone.' Blood was drawn from normal human donors through 15-gauge, uncoated, disposable metal needles attached to plastic tubing and was collected in tubes containing an aqueous solution of the disodium * Submitted for publication February 26, 1964; accepted July 7, 1964. This investigation was carried out under contract salt of EDTA as an anticoagulant (1 part EDTA: 9 parts blood). The final concentration of EDTA in blood was 0.005 M. Platelet-rich plasma was obtained by differential centrifugation (6). Unless specified otherwise, platelets from 3-ml portions of platelet-rich plasma were sedimented (6) and washed twice with and finally resuspended in 1.8 ml of Tris-buffered saline, pH 7.5 (6), containing potassium chloride (0.004 M), glucose (0.0055 M), and EDTA (0.0013 M). The washing procedures were performed at 40 C and required approximately 30 minutes. Platelet counts were performed on these suspensions by the method of Brecher and Cronkite (7). The final concentration of platelets was approximately 250,000 per mm'. The washed platelets then were incubated without agitation at 370 C under various experimental conditions. After incubation, the platelets to be analyzed for potassium and ATP were washed once with Tris-buffered saline containing EDTA but no potassium or glucose. Those to be analyzed for sodium were washed once with Tris-buffered potassium chloride (0.155 M) containing EDTA. The final washing procedure was performed at 40 C and required approximately 10 minutes. The platelets then were sedimented by centrifugation at 22,000 g for 5 minutes at 40 C and lysed in 3 ml of a 3% solution of trichloroacetic acid. Potassium and sodium in the lysates were measured by use of a flame photometer employing an internal lithium standard. ATP, in most experiments, was measured after fractionation of the lysate on a Dowex-1 anion exchange column by use of a Beckman model DU spectrophotometer reading at 260 mg (8). In other experiments ATP was measured either by the firefly luminescence method or e...

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Section: Discussionmentioning

confidence: 99%

Effects of Thrombin on the Potassium and ATP Content of Platelets *

Zieve¹,

Gamble²,

Jackson³

1964

J. Clin. Invest.

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“…The mechanism by which a lowered pH reduces platelet adhesiveness, permitting platelets to be centrifuged and resuspended, is unclear. At a low pH platelets do not readily undergo "viscous metamorphosis" (26) and are less sensitive to thrombin-induced aggregation (27). The latter effect may in part account for the decreased adhesiveness of platelets in citrate plasma at pH 6.5.…”

mentioning

confidence: 99%

Platelet Sequestration in Man. I. Methods*

Aster¹,

Jandl²

1964

J. Clin. Invest.

806

179

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“…This reaction does not consist simply of the coagulation of fibrinogen with entrapment of platelets in the fibrin mesh. Under usual conditions divalent cations are required for thrombin-induced platelet aggregation but not for clotting of fibrinogen (5,6). Electron photomicrographs of platelet aggregates show no striated fibrin strands between adherent platelets (7).…”

mentioning

confidence: 99%

Role of Platelet Fibrinogen in the Reactions of Platelets to Thrombin*

Morse¹,

Jackson²,

Conley³

1965

J. Clin. Invest.

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Washed human blood platelets contain a clottable protein that is similar to, if not identical with, plasma fibrinogen (1-4). After incubation with trypsin under appropriate conditions, platelets remain morphologically intact but no longer contain clottable protein (5). Trypsinized platelets, unlike normal platelets, are not aggregated by fresh serum or by a solution of thrombin and calcium chloride. When resuspended in plateletfree plasma or in a buffered solution of fibrinogen containing glucose, trypsinized platelets produce retraction of clots formed by thrombin; during the formation of the clot and its subsequent retraction, trypsinized platelets aggregate and undergo the usual changes of viscous metamorphosis (5). These observations suggest that fibrinogen on the surface of platelets is involved in the reaction of platelets to thrombin. This reaction does not consist simply of the coagulation of fibrinogen with entrapment of platelets in the fibrin mesh. Under usual conditions divalent cations are required for thrombin-induced platelet aggregation but not for clotting of fibrinogen (5, 6). Electron photomicrographs of platelet aggregates show no striated fibrin strands between adherent

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Studies on Thrombin-Induced Platelet Agglutination

Cited by 41 publications

References 27 publications

Effects of Thrombin on the Potassium and ATP Content of Platelets *

Effects of Thrombin on the Potassium and ATP Content of Platelets *

Platelet Sequestration in Man. I. Methods*

Role of Platelet Fibrinogen in the Reactions of Platelets to Thrombin*

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