Quantification of the adhesion of platelets in hamster venules in vivo

1982 ◽  
Vol 215 (1199) ◽  
pp. 135-145 ◽  
Keyword(s):  
Platelet Rich Plasma ◽  
Fluorescein Isothiocyanate ◽  
Adenosine Diphosphate ◽  
Cheek Pouch ◽  
Video Tape ◽  
Flow Through ◽  
Platelet Aggregates ◽  
The Mean ◽  
Adhesion Of Platelets

(i) Citrated platelet-rich plasma freshly prepared from golden hamsters was mixed with fluorescein isothiocyanate (FITC) which made the platelets fluorescent. These platelets were injected intravenously into anaesthetized hamsters with exteriorized cheek pouch preparations superfused at 37 °C with Krebs-bicarbonate solution. The exposed microcirculation was observed microscopically by bright field or fluores­cent illumination. The flowing and sticking of fluorescent platelets was recorded on video tape for quantitative analysis. (ii) In four experiments 22–36%, mean 28%, of fluorescent platelets were circulating 2-3 h after their injection. In seven experiments the fluorescent platelets accounted for 0.6–3.3 %, mean 1.7 %, of circulating platelets. (iii) In venules 20–60 μm in diameter small proportions, mean 5.4%, of circulating fluorescent platelets stopped moving by sticking to the vessel walls. About 80 % of these platelets stuck for up to 1 s, a further 10-15% for up to 5 s, and only about 2% for longer than 2 min. There was an inverse relation between size of venule and proportion of platelets sticking in them. (iv) There was a direct relation between the mean velocities at which platelets flowed through the venules and the sizes of the venules. In the smaller venules the velocity distribution of the platelets had a clear maximum which was not as evident in larger venules. (v) In a few observations on arterioles, flowing platelets could not be seen, and arrested platelets only in a dilatation and at a capillary branch. (vi) Ethylenediamine tetraacetate in the superfusing fluid decreased platelet sticking in venules but did not abolish it. (vii) Adenosine diphosphate in the superfusing fluid caused the appear­ance of platelet aggregates in venules and of sticking platelets in arterioles during progressive diminution in blood flow through both types of vessel. (viii) The observations make it improbable that the release of platelet constituents affects normal venules or arterioles except, possibly, where haemodynamic conditions are affected by wall irregularities such as dilations or branching.

Quantification of Platelet Adsesion in vivo

1979 ◽  
Author(s):  
H. Kortenhaus ◽  
G.V.R. Bom
Keyword(s):  
Fluorescence Microscopy ◽  
Small Proportion ◽  
Platelet Rich Plasma ◽  
Fluorescein Isothiocyanate ◽  
Cheek Pouch ◽  
Golden Hamsters ◽  
Cardiac Blood ◽  
Acid Citrate Dextrose ◽  
Citrate Dextrose

Golden hamsters (80-100g) were anaesthetised with pentobarbital and cardiac blood was collected into acid-citrate dextrose. Platelet-rich plasma brought to pH 6.2 was incubated at 37° with fluorescein-isothiocyanate (FITC: 100 μg/ml) for 10 min (Kortenhaus , Webelmann and Schroer: to be published). The platelets were injected i.v. into another hamster and observed in the cheek pouch circulation by fluorescence microscopy at x 500.In venules a small proportion of platelets were arrested, most for less than one sec., about 20% for up to 2 min and about 3% for longer. There was no correlation with rolling granulocyte frequencies (A therton & Born, 1972, Journal of Fhysiology, 222, 447).

scholarly journals Do patients with thromboembolic disease have circulating platelet aggregates?

Blood ◽  
1984 ◽  
Vol 64 (1) ◽  
pp. 205-209 ◽  
Author(s):  
FH Kohanna ◽  
MH Smith ◽  
EW Salzman
Keyword(s):  
Platelet Rich Plasma ◽  
Venous Blood ◽  
Adenosine Diphosphate ◽  
Normal Subjects ◽  
Thromboembolic Disease ◽  
Circulating Platelet Aggregates ◽  
Platelet Aggregates ◽  
Lower Ratio

Reports of circulating platelet aggregates (ie, microemboli) in thromboembolism and other vascular disorders are based on a method (Wu and Hoak , 1974) in which venous blood is collected via scalp vein needle and tubing into either formaldehyde, which fixes aggregates, or EDTA, which disperses them. The ratio of platelet counts in platelet- rich plasma (PRP) from the two blood samples after centrifugation is interpreted as a measure of platelet aggregates in the circulation in vivo. We compared this standard Wu and Hoak technique with a modified one, in which blood was drawn directly into a syringe, and with a third method that avoided centrifugation by counting single platelets in whole blood. Both modified techniques could detect aggregates generated in vitro with adenosine diphosphate (ADP). In 12 normal subjects, the three methods were equivalent, but in 37 patients with thromboembolic disorders, the standard Wu and Hoak method gave a lower ratio than the other methods. Similar results were found in a subset of eight patients with myocardial infarction. Heparin treatment of patients did not influence the results. The data suggest that formation of platelet aggregates occurred during venipuncture. Platelets may be hyperactive in patients with thromboembolic disease and may form aggregates in vitro during collection, but the concept of chronic microembolism in such patients should be reassessed.

scholarly journals Do patients with thromboembolic disease have circulating platelet aggregates?

Blood ◽  
1984 ◽  
Vol 64 (1) ◽  
pp. 205-209 ◽  
Author(s):  
FH Kohanna ◽  
MH Smith ◽  
EW Salzman
Keyword(s):  
Platelet Rich Plasma ◽  
Venous Blood ◽  
Adenosine Diphosphate ◽  
Normal Subjects ◽  
Thromboembolic Disease ◽  
Circulating Platelet Aggregates ◽  
Platelet Aggregates ◽  
Lower Ratio

Abstract Reports of circulating platelet aggregates (ie, microemboli) in thromboembolism and other vascular disorders are based on a method (Wu and Hoak , 1974) in which venous blood is collected via scalp vein needle and tubing into either formaldehyde, which fixes aggregates, or EDTA, which disperses them. The ratio of platelet counts in platelet- rich plasma (PRP) from the two blood samples after centrifugation is interpreted as a measure of platelet aggregates in the circulation in vivo. We compared this standard Wu and Hoak technique with a modified one, in which blood was drawn directly into a syringe, and with a third method that avoided centrifugation by counting single platelets in whole blood. Both modified techniques could detect aggregates generated in vitro with adenosine diphosphate (ADP). In 12 normal subjects, the three methods were equivalent, but in 37 patients with thromboembolic disorders, the standard Wu and Hoak method gave a lower ratio than the other methods. Similar results were found in a subset of eight patients with myocardial infarction. Heparin treatment of patients did not influence the results. The data suggest that formation of platelet aggregates occurred during venipuncture. Platelets may be hyperactive in patients with thromboembolic disease and may form aggregates in vitro during collection, but the concept of chronic microembolism in such patients should be reassessed.

Accutin, a New Disintegrin, Inhibits Angiogenesis In Vitro and In Vivo by Acting as Integrin vβ3 Antagonist and Inducing Apoptosis

Blood ◽  
1998 ◽  
Vol 92 (9) ◽  
pp. 3268-3276 ◽  
Author(s):  
Chia Hsin Yeh ◽  
Hui-Chin Peng ◽  
Tur-Fu Huang
Keyword(s):  
Endothelial Cells ◽  
Umbilical Vein ◽  
Fluorescein Isothiocyanate ◽  
Adenosine Diphosphate ◽  
Tube Formation ◽  
Platelet Glycoprotein ◽  
Dependent Manner ◽  
Antiangiogenic Effect

Abstract Endothelial integrins play an essential role in angiogenesis and cell survival. Accutin, a new member of disintegrin family derived from venom of Agkistrodon acutus, potently inhibited human platelet aggregation caused by various agonists (eg, thrombin, collagen, and, adenosine diphosphate [ADP]) through the blockade of fibrinogen binding to platelet glycoprotein IIb/IIIa (ie, integrin IIbβ3). In this report, we describe that accutin specifically inhibited the binding of monoclonal antibody (MoAb) 7E3, which recognizes integrin vβ3, to human umbilical vein endothelial cells (HUVECs), but not those of other anti-integrin MoAbs such as 2β1, 3β1, and 5β1. Moreover, accutin, but not the control peptide GRGES, dose-dependently inhibited the 7E3 interaction with HUVECs. Both 7E3 and GRGDS, but not GRGES or Integrelin, significantly blocked fluorescein isothiocyanate-conjugated accutin binding to HUVEC. In functional studies, accutin exhibited inhibitory effects on HUVEC adhesion to immobilized fibrinogen, fibronectin and vitronectin, and the capillary-like tube formation on Matrigel in a dose- and RGD-dependent manner. In addition, it exhibited an effective antiangiogenic effect in vivo when assayed by using the 10-day-old embryo chick CAM model. Furthermore, it potently induced HUVEC apoptotic DNA fragmentation as examined by electrophoretic and flow cytometric assays. In conclusion, accutin inhibits angiogenesis in vivo and in vitro by blocking integrin vβ3 of endothelial cells and by inducing apoptosis. The antiangiogenic activity of disintegrins might be explored as the target of developing the potential antimetastatic agents. © 1998 by The American Society of Hematology.

scholarly journals The Induction of Platelet Aggregates in Healthy Subjects by Venousocclusion

1977 ◽  
Author(s):  
D.A. F. Chamone ◽  
J. Vermylen
Keyword(s):  
Healthy Subjects ◽  
Light Transmission ◽  
Diastolic Pressure ◽  
Platelet Rich Plasma ◽  
In Vivo Evaluation ◽  
Modified Method ◽  
Circulating Platelet Aggregates ◽  
Platelet Aggregates ◽  
Set Up

Circulating platelet aggregates have been observed in various clinical conditions (Wu and Hoak, Lancet, 1974, ii, 924). Using a slightly modified method, we have found that platelet aggregates can be induced in vivo in healthy subjects.Nine volunteers (7 males, 2 females, age 23-38 years) were studied. Blood was drawn from an antecubital vein of one arm immediately before and of the other arm after twenty minutes of occlusion midway between systolic and diastolic pressure. The ratio of the platelet count in platelet-rich plasma (PRP) obtained from blood collected on forma lin-EDTA to that from blood collected on EDTA only was 0.934 + 0.028 (mean ± S.E .) before and 0.768 ± 0.033 after occlusion (p < 0.001 ). Spontaneous aggregation in PRP, measured as percent increase in light transmission during 10 minutes of stirring in the a gg re gome ter, was 4 .20 ± 1.17 before and 3 .80 + I .69 after occlusion (p > 0 .1).This system may help elucidate some of the mechanisms involved in the generation of circulating platelet aggregates. It may also constitute a simple set-up for the in vivo evaluation of drugs affecting platelet function.

Tannic acid elicits neurogenic plasma exudation from the in situ hamster cheek pouch

1998 ◽  
Vol 274 (1) ◽  
pp. R237-R242
Author(s):  
Xiao-Pei Gao
Keyword(s):  
Tannic Acid ◽  
Biosynthetic Pathway ◽  
Fluorescein Isothiocyanate ◽  
Cheek Pouch ◽  
Site Formation ◽  
Hamster Cheek Pouch ◽  
Plasma Exudation ◽  
Synthase Inhibitor

The purpose of this study was to determine whether tannic acid elicits neurogenic plasma exudation from the oral mucosa in vivo and, if so, whether this response is transduced in part by thel-arginine-nitric oxide (NO) biosynthetic pathway. Using intravital microscopy, we found that suffusion of tannic acid elicits significant concentration-dependent leaky site formation and increase in clearance of fluorescein isothiocyanate-dextran (molecular mass 70 kDa) from the in situ hamster cheek pouch ( P < 0.05). These effects are significantly attenuated by two selective, but structurally distinct, nonpeptide neurokinin-1 (NK1) receptor antagonists, CP-96,345 and RP-67580, but not by CP-96,344, the 2R,3R enantiomer of CP-96,345. N G-nitrol-arginine methyl ester (l-NAME), an NO synthase inhibitor, but notd-NAME, significantly attenuates tannic acid-induced responses.l-Arginine, but notd-arginine, reverses the attenuating effects of l-NAME. We conclude that tannic acid elicitsl-arginine-NO biosynthetic pathway-dependent neurogenic plasma exudation from the in situ hamster cheek pouch.

scholarly journals Fibrinogen-independent aggregation and deaggregation of human platelets: studies in two afibrinogenemic patients

Blood ◽  
1987 ◽  
Vol 70 (1) ◽  
pp. 221-226 ◽  
Author(s):  
M Cattaneo ◽  
RL Kinlough-Rathbone ◽  
A Lecchi ◽  
C Bevilacqua ◽  
MA Packham ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Plasma Proteins ◽  
Platelet Rich Plasma ◽  
Platelet Activating Factor ◽  
Adenosine Diphosphate ◽  
Human Platelets ◽  
Human Fibrinogen ◽  
Control Subjects ◽  
Platelet Aggregates ◽  
And Control

Abstract Platelets from two afibrinogenemic patients were used to determine whether fibrinogen is essential for platelet aggregation and to examine whether released fibrinogen contributes to the stabilization of platelet aggregates when platelets have been induced to aggregate and release their granule contents by stimulation with thrombin. The addition of adenosine diphosphate (ADP) to platelet-rich plasma (PRP) or to suspensions of washed platelets from the afibrinogenemic patients caused the formation of small aggregates, which was either not inhibited or only slightly inhibited by the F(ab')2 fragments of an antibody to fibrinogen but was inhibited by an antibody (10E5) to glycoprotein IIb/IIIa. Thus there is a component of ADP-induced platelet aggregation that is not dependent on fibrinogen or other plasma proteins but is dependent on glycoprotein IIb/IIIa. There was little difference in the extent of aggregation and the release of granule contents of normal and afibrinogenemic platelets in response to the release-inducing agents collagen, platelet-activating factor (PAF), sodium arachidonate, or thrombin. With normal or afibrinogenemic platelets, aggregation by thrombin (0.2 U/mL or higher) was not inhibited by the F(ab')2 fragments of an antibody to human fibrinogen. Deaggregation by combinations of inhibitors of platelets aggregated by 1 U/mL thrombin showed no difference between platelets from afibrinogenemic and control subjects, indicating that released fibrinogen does not make a major contribution to the stabilization of platelet aggregates formed by thrombin stimulation.

scholarly journals Dexamethasone attenuates acute macromolecular efflux increase evoked by smokeless tobacco extract

1999 ◽  
Vol 87 (2) ◽  
pp. 619-625 ◽  
Author(s):  
Xiao-Pei Gao ◽  
Syed R. Akhter ◽  
Hiroyuki Ikezaki ◽  
Dennis Hong ◽  
Israel Rubinstein
Keyword(s):  
Oral Mucosa ◽  
Smokeless Tobacco ◽  
Fluorescein Isothiocyanate ◽  
Cheek Pouch ◽  
Site Formation ◽  
Hamster Cheek Pouch ◽  
Acute Increase ◽  
Tobacco Extract

The purpose of this study was to determine whether dexamethasone attenuates the acute increase in macromolecular efflux from the oral mucosa elicited by an aqueous extract of smokeless tobacco (STE) in vivo, and, if so, whether this response is specific. Using intravital microscopy, we found that 20-min suffusion of STE elicited significant, concentration-related leaky site formation and an increase in clearance of fluorescein isothiocyanate-labeled dextran (FITC-dextran; mol mass 70 kDa) from the in situ hamster cheek pouch ( P < 0.05). This response was significantly attenuated by dexamethasone (10 mg/kg iv). Dexamethasone also attenuated the bradykinin-induced leaky site formation and the increase in clearance of FITC-dextran from the cheek pouch. However, it had no significant effects on adenosine-induced responses. Dexamethasone had no significant effects on baseline arteriolar diameter and on bradykinin-induced vasodilation in the cheek pouch. Collectively, these data indicate that dexamethasone attenuates, in a specific fashion, the acute increase in macromolecular efflux from the in situ oral mucosa evoked by short-term suffusion of STE. We suggest that corticosteroids mitigate acute oral mucosa inflammation elicited by smokeless tobacco.

Nitric oxide accounts for histamine-induced increases in macromolecular extravasation

1994 ◽  
Vol 266 (6) ◽  
pp. H2369-H2373 ◽  
Author(s):  
W. G. Mayhan
Keyword(s):  
Nitric Oxide ◽  
Fluorescent Microscopy ◽  
Fluorescein Isothiocyanate ◽  
Cheek Pouch ◽  
Hamster Cheek Pouch ◽  
Before And After ◽  
Subsequent Activation ◽  
Ly 83583

The goal of this study was to determine the role of nitric oxide in histamine-induced increases in macromolecular extravasation in the hamster cheek pouch in vivo. We used intravital fluorescent microscopy and fluorescein isothiocyanate dextran (FITC-dextran; mol wt = 70,000 K) to examine extravasation from postcapillary venules in response to histamine before and after application of an enzymatic inhibitor of nitric oxide, NG-monomethyl-L-arginine (L-NMMA; 1.0 microM). Increases in extravasation of macromolecules were quantitated counting the number of venular leaky sites. Histamine (1.0 and 5.0 microM) increased the number of venular leaky sites from zero (basal conditions) to 11 +/- 1 and 21 +/- 2/0.11 cm2, respectively. Superfusion of L-NMMA (1.0 microM) and LY-83583 (1.0 microM) significantly decreased histamine-induced formation of venular leaky sites, whereas L-arginine (100 microM) potentiated histamine-induced formation of venular leaky sites. In contrast, superfusion of NG-monomethyl-D-arginine (1.0 microM) did not inhibit the formation of venular leaky sites in response to histamine. Thus the findings of the present study suggest that production of nitric oxide, and subsequent activation of guanylate cyclase, plays an important role in macromolecular efflux in vivo in response to histamine.

scholarly journals Zinc-induced platelet aggregation is mediated by the fibrinogen receptor and is not accompanied by release or by thromboxane synthesis

Blood ◽  
1985 ◽  
Vol 66 (1) ◽  
pp. 213-219 ◽  
Author(s):  
P Heyns A du ◽  
A Eldor ◽  
R Yarom ◽  
G Marx
Keyword(s):  
Platelet Aggregation ◽  
Dense Body ◽  
Platelet Rich Plasma ◽  
Adenosine Monophosphate ◽  
Adenosine Diphosphate ◽  
Creatine Phosphate ◽  
Calcium Flux ◽  
Fibrinogen Receptor ◽  
Induced Aggregation

Abstract We demonstrate that zinc (0.1 to 0.3 mmol/L) induces aggregation of washed platelet suspensions. Higher concentrations (1 to 3 mmol/L) of zinc were needed to aggregate platelets in platelet-rich plasma obtained from blood anticoagulated with low-molecular-weight heparin, probably due to the binding of zinc to the plasma proteins. Zinc- induced aggregation of normal washed platelets required added fibrinogen and no aggregation occurred with thrombasthenic platelets or with normal platelets pretreated with a monoclonal antibody (10E5) that blocks the platelet fibrinogen receptor. These data indicate that the platelet membrane fibrinogen receptor-glycoproteins IIb and IIIa mediate the effect of zinc. Zinc-induced aggregation was blocked by the agent TMB-8, which interferes with the internal calcium flux, and by prostacyclin, which elevates platelet cyclic adenosine monophosphate levels. Zinc-induced aggregation was not accompanied by thromboxane synthesis or by the secretion of dense-body serotonin and was not affected by preexposure of platelets to acetylsalicylic acid. Experiments with creatine phosphate/creatine phosphokinase showed that the zinc effect on platelets was independent of extracellular adenosine diphosphate (ADP). Zinc had an additive effect when platelet aggregation was stimulated with subthreshhold concentrations of collagen or ADP. Together with the known effects of nutritional zinc on in vivo bleeding, on platelet aggregation, and on lipid metabolism, the results suggest that zinc may have an important bearing on normal hemostasis, thrombosis, and atherosclerosis.

Sign in / Sign up

Export Citation Format

Share Document