Congenital Deficiency of Alpha-2-Adrenoceptors on Human Platelets : Description of Two Cases

1987 ◽  
Vol 58 (04) ◽  
pp. 1012-1016 ◽  
Author(s):  
Giacomo Tamponi ◽  
Antonella Pannocchia ◽  
Carlo Arduino ◽  
Mario Bazzan ◽  
Nadine Della Dora ◽  
...  
Keyword(s):  
Radioligand Binding ◽  
Adenine Nucleotides ◽  
Thromboxane A2 ◽  
Inhibitory Effect ◽  
Human Platelets ◽  
Platelet Factor ◽  
Congenital Deficiency ◽  
Normal Limits ◽  
Flux Aggregation ◽  
Induced Aggregation

SummaryThe biochemistry and functionality of platelets from two related subjects (mother and son) with alpha-2-adrenoceptor-deficient platelets has been evaluated. Radioligand binding experimentes with the specific alpha-2-adrenergic-receptor antagonist, 3H-yohimbine, showed a drastic reduction of alpha-2-adrenoceptors in platelets from both subjects in comparison with the control values. Electron microscopy studies revealed a normal morphology and a normal number of alpha granules and dense bodies. Levels of adenine nucleotides; 5-hydroxytryptamine; B-thromboglobulin; platelet-factor-4 and thromboxane A2 production were within normal limits.Platelet aggregation and 5-hydroxytryplamine production in response to adrenalin (at concentrations up to 50 μM) were absent, whereas ADP, AA, PAF, collagen and thrombin-induced aggregation, secretion, Ca++ flux and thromboxane A2 production were normal.The inhibitory effect caused by different concentrations of prostacyclin on Ca++ flux, aggregation, secretion and thromboxane A2 production of platelet functionally lacking of alpha-2-adrenoceptor was not distinguishable from control platelets and platelets preincubated with yohimbine.

scholarly journals Human group II 14 kDa phospholipase A2 activates human platelets

1997 ◽  
Vol 327 (1) ◽  
pp. 259-265 ◽  
Author(s):  
János POLGÁR ◽  
Ruth M. KRAMER ◽  
Suzane L. UM ◽  
Joseph A. JAKUBOWSKI ◽  
Kenneth J. CLEMETSON
Keyword(s):  
Phospholipase A2 ◽  
Platelet Activation ◽  
Heparan Sulphate ◽  
Thromboxane A2 ◽  
Inhibitory Effect ◽  
Human Platelets ◽  
Time Dependent ◽  
Human Group ◽  
Group Ii ◽  
Induced Aggregation

Recombinant human group II phospholipase A2 (sPLA2) added to human platelets in the low μg/ml range induced platelet activation, as demonstrated by measurement of platelet aggregation, thromboxane A2 generation and influx of intracellular free Ca2+ concentration and by detection of time-dependent tyrosine phosphorylation of platelet proteins. The presence of Ca2+ at low millimolar concentrations is a prerequisite for the activation of platelets by sPLA2. Mg2+ cannot replace Ca2+. Mg2+, given in addition to the necessary Ca2+, inhibits sPLA2-induced platelet activation. Pre-exposure to sPLA2 completely blocked the aggregating effect of a second dose of sPLA2. Albumin or indomethacin inhibited sPLA2-induced aggregation, similarly to the inhibition of arachidonic acid-induced aggregation. Platelets pre-treated with heparitinase or phosphatidylinositol-specific phospholipase C lost their ability to aggregate in response to sPLA2, although they still responded to other agonists. This suggests that a glycophosphatidylinositol-anchored platelet-membrane heparan sulphate proteoglycan is the binding site for sPLA2 on platelets. Previous reports have stated that sPLA2 is unable to activate platelets. The inhibitory effect of albumin and Mg2+, frequently used in aggregation studies, and the fact that isolated platelets lose their responsiveness to sPLA2 relatively quickly, may explain why the platelet-activating effects of sPLA2 have not been reported earlier.

scholarly journals ADP and epinephrine-induced release of platelet fibrinogen

Blood ◽  
1981 ◽  
Vol 58 (4) ◽  
pp. 797-802 ◽  
Author(s):  
KL Kaplan ◽  
MJ Dauzier ◽  
S Rose
Keyword(s):  
Platelet Aggregation ◽  
Bovine Serum Albumin ◽  
Adenine Nucleotides ◽  
Adenosine Diphosphate ◽  
Human Platelets ◽  
Dense Granule ◽  
Fibrinogen Concentration ◽  
Platelet Factor ◽  
Granule Proteins ◽  
Induced Aggregation

Abstract Human platelets gel-filtered into Tyrode's buffer containing 1 mM Mg++ and 0.35% bovine serum albumin were studied to determine whether they would undergo biphasic aggregation and release of alpha-granule proteins in response to adenosine diphosphate (ADP) or epinephrine without addition of exogenous fibrinogen. Fibrinogen concentration in the supernatant of unaggregated gel-filtered platelets was less than 1 pmole/ml. With addition of ADP or epinephrine, biphasic aggregation was seen, with release of platelet fibrinogen, beta-thromboglobulin, and platelet factor 4. Fibrinogen concentration in the supernatant after aggregation ranged from 15 to 70 pmole/ml. Release of the alpha-granule proteins by epinephrine was coincidental with release of the dense granule adenine nucleotides. Aggregation and alpha-granule protein release by both ADP and epinephrine were inhibited by added Ca++ at 1-- 2 mM. The ability of gel-filtered platelets to undergo ADP- and epinephrine-induced aggregation and release in the absence of exogenous fibrinogen suggests that released platelet fibrinogen may be able to fulfill the requirement for fibrinogen in ADP- and epinephrine-induced platelet aggregation and release.

Effects of amiloride analogues on AVP binding and activation of V1-receptor-expressing cells

1992 ◽  
Vol 262 (1) ◽  
pp. E76-E86 ◽  
Author(s):  
M. Thibonnier ◽  
A. L. Bayer ◽  
M. S. Simonson ◽  
J. G. Douglas
Keyword(s):  
Intracellular Calcium ◽  
Radioligand Binding ◽  
Mesangial Cells ◽  
Receptor Site ◽  
Inhibitory Effect ◽  
Human Platelets ◽  
Dependent Manner ◽  
Glomerular Mesangial Cells ◽  
Cell Contraction ◽  
Induced Aggregation

We tested the interactions between amiloride analogues and V1 vascular arginine vasopressin (AVP) receptors of human platelets, rat glomerular mesangial cells, and A7r5 smooth muscle cells by using radioligand binding techniques, intracellular calcium monitoring, platelet aggregation, and cell contraction techniques. Amiloride analogues were competitive inhibitors of both the agonist [3H]AVP and the tritiated V1 antagonist [1-(beta-mercapto-beta,beta-cyclopentamethylenepropionic acid), 2-O-methyl)tyrosine]AVP ([3H]d(CH2)5Tyr(Me)AVP) binding to V1 AVP receptors in the three different cell types used. The order of potency was ethylisopropyl amiloride (EIPA) greater than Benzamil greater than amiloride. AVP mobilization of intracellular calcium was blocked by the V1 antagonist d(CH2)5Tyr(Me)AVP and was reduced by EIPA in a dose-dependent manner. Moreover, EIPA also inhibited prostaglandin F2 alpha mobilization of intracellular calcium. Alkalinization of the intracellular pH with ammonium chloride reversed the inhibitory effect of EIPA but not that of the V1 antagonist on AVP-induced calcium mobilization. Both amiloride and EIPA blocked AVP-induced aggregation of human platelets and contraction of mesangial cells and glomeruli preparations independently of receptor site antagonism. In conclusion, amiloride analogues interfere with activation of V1 vascular receptors by AVP at different levels including binding to the receptor site, mobilization of intracellular calcium, cell contraction or aggregation, and presumably alteration of intracellular ion transports.

scholarly journals ADP and epinephrine-induced release of platelet fibrinogen

Blood ◽  
1981 ◽  
Vol 58 (4) ◽  
pp. 797-802
Author(s):  
KL Kaplan ◽  
MJ Dauzier ◽  
S Rose
Keyword(s):  
Platelet Aggregation ◽  
Bovine Serum Albumin ◽  
Adenine Nucleotides ◽  
Adenosine Diphosphate ◽  
Human Platelets ◽  
Dense Granule ◽  
Fibrinogen Concentration ◽  
Platelet Factor ◽  
Granule Proteins ◽  
Induced Aggregation

Human platelets gel-filtered into Tyrode's buffer containing 1 mM Mg++ and 0.35% bovine serum albumin were studied to determine whether they would undergo biphasic aggregation and release of alpha-granule proteins in response to adenosine diphosphate (ADP) or epinephrine without addition of exogenous fibrinogen. Fibrinogen concentration in the supernatant of unaggregated gel-filtered platelets was less than 1 pmole/ml. With addition of ADP or epinephrine, biphasic aggregation was seen, with release of platelet fibrinogen, beta-thromboglobulin, and platelet factor 4. Fibrinogen concentration in the supernatant after aggregation ranged from 15 to 70 pmole/ml. Release of the alpha-granule proteins by epinephrine was coincidental with release of the dense granule adenine nucleotides. Aggregation and alpha-granule protein release by both ADP and epinephrine were inhibited by added Ca++ at 1-- 2 mM. The ability of gel-filtered platelets to undergo ADP- and epinephrine-induced aggregation and release in the absence of exogenous fibrinogen suggests that released platelet fibrinogen may be able to fulfill the requirement for fibrinogen in ADP- and epinephrine-induced platelet aggregation and release.

Effect of PGI2 and Its Derivatives on Platelet Adherence Aggregation and PF3 Availability

1979 ◽  
Author(s):  
L. Fésüs ◽  
I. Stadler ◽  
J. Hársfalvi ◽  
M. Balogh ◽  
E. Kovács ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Inhibitory Effect ◽  
Human Platelets ◽  
Glass Beads ◽  
Ionophore A23187 ◽  
Inhibit Platelet Aggregation ◽  
Platelet Factor ◽  
Platelet Adherence ◽  
Induced Aggregation ◽  
Higher Doses

10-8M PGI2-Na completely inhibited collagen induced aggregation of human platelets and the concomitant appearance of platelet factor 3 activity, but did not affect the adherence of platelets to collagen fibrils. At the same time, the presence of PGI2-Na could prevent the retention of platelets by glass beads.Comparing to the inhibition of ADP induced aggregation a higher dose of PGI2-Na was needed to inhibit platelet aggregation by ionophore A23187. Furthermore, unlike ADP aggregation, increasing dose of ionophore could counteract the inhibitory effect of PGI2-Na. The shift of platelet actin from G to F from during ionophore aggregation could be prevented by appropriate dose of PGI2-Na. PGI2 derivatives (Chinoin, Hungary) with increased stability, although in higher doses, exerted activities similar to PGI2-Na.

Opposite Effect of Lysine on Platelet Aggregation Induced by Arachidonate and by Other Aggregants

1982 ◽  
Vol 48 (01) ◽  
pp. 078-083 ◽  
Author(s):  
C Ts'ao ◽  
S J Hart ◽  
D V Krajewski ◽  
P G Sorensen
Keyword(s):  
Platelet Aggregation ◽  
Secondary Phase ◽  
Aminocaproic Acid ◽  
Adenosine Diphosphate ◽  
Inhibitory Effect ◽  
Human Platelets ◽  
Primary Phase ◽  
High Doses ◽  
The Many ◽  
Induced Aggregation

SummaryEarlier, we found that ε-aminocaproic acid (EACA) inhibited human platelet aggregation induced by adenosine diphosphate (ADP) and collagen, but not aggregation by arachidonic acid (AA). Since EACA is structurally similar to lysine, yet these two agents exhibit vast difference in their antifibrinolytic activities, we chose to study the effect of lysine on platelet aggregation. We used L-lysine-HCl in these studies because of its high solubility in aqueous solutions while causing no change in pH when added to human plasma. With lysine, we repeatedly found inhibition of ADP-, collagen- and ristocetin-induced aggregation, but potentiation of AA-induced aggregation. Both the inhibitory and potentiation effects were dose-dependent. Low doses of lysine inhibited the secondary phase of aggregation; high doses of it also inhibited the primary phase of aggregation. Potentiation of AA-induced aggregation was accompanied by increased release of serotonin and formation of malondialdehyde. These effects were not confined to human platelets; rat platelets were similarly affected. Platelets, exposed to lysine and then washed and resuspended in an artificial medium not containing lysine, remained hypersensitive to AA, but no longer showed decreased aggregation by collagen. Comparing the effects of lysine with equimolar concentrations of sucrose, EACA, and α-amino-n-butyric acid, we attribute the potent inhibitory effect of lysine to either the excess positive charge or H+ and C1− ions. The -NH2 group on the α-carbon on lysine appears to be the determining factor for the potentiation effect; the effect seems to be exerted on the cyclooxygenase level of AA metabolism. Lysine and other chemicals with platelet-affecting properties similar to lysine may be used as a tool for the study of the many aspects of a platelet aggregation reaction.

scholarly journals Loss of 111Indium as indicator of platelet injury

Blood ◽  
1981 ◽  
Vol 58 (2) ◽  
pp. 350-353 ◽  
Author(s):  
JH Joist ◽  
RK Baker
Keyword(s):  
Small Molecules ◽  
Adenine Nucleotides ◽  
Human Platelets ◽  
Metabolic Energy ◽  
Platelet Factor ◽  
Platelet Protein ◽  
Threshold Rate ◽  
Immune Injury ◽  
Triton X

Abstract We previously demonstrated that platelets can be labeled with 111Inoxine with high labeling efficiency and that 111In is not liberated from labeled platelets during the platelet release reaction or prolonged in vitro storage. In view of these findings, we examined the potential usefulness of loss of 111In from labeled platelets as an indicator or platelet damage by comparing the loss of 111In with that of 51Cr and LDH (in some experiments also with platelet factor 3 availability) under different conditions of platelet injury. When washed human platelets labeled with either 51Cr-chromate or 111In-oxine were exposed to increasing concentrations of detergents (Triton X-100, lysolecithin), threshold, rate, and extent of loss of 111In, 51Cr and, LDH were similar. In contrast, when labeled platelets were depleted of metabolic energy by incubation in glucose-free Tyrode albumin solution or glucose-depleted plasma in the presence of antimycin A and 2-deoxy-D- glucose, loss of 51Cr (and PF3a) occurred earlier and progressed at a faster rate than that of 111In or LDH. Similar results were obtained when platelets were exposed to increasing concentrations of PlA1 antibody, causing complement-mediated immune injury. The findings indicate that with certain agents that cause rapid platelet disruption (lysis), different platelet constituents are lost at similar rates. However, under conditions of more subtle or slowly progressive platelet injury, small molecules such as adenine nucleotides (51Cr) may escape earlier and at faster rates than larger molecules such as LDH or 111In- binding platelet protein. Thus, neither 111In loss nor LDH loss appear to be suitable indicators for sublytic or prelytic platelet injury.

Effect Of Solvents On Indium-111 Oxine Transport In Human Platelets And On Platelet Function In Vitro

1981 ◽  
Author(s):  
T Tsukada
Keyword(s):  
Platelet Function ◽  
Kinetic Constant ◽  
Inhibitory Effect ◽  
Human Platelets ◽  
Polysorbate 80 ◽  
Autologous Plasma ◽  
Indium 111 ◽  
Induced Aggregation ◽  
Water Space

Mechanism of Indium-111 oxine(In) transport in human platelets in buffered saline and the effect of In-labeling on platelet function were studied using In dissolved in 25% of ethanol in saline (In-ES) or 0.01% of polysorbate 80 in HEPES buffer(In-PH). Increase in temperature up to 37° C progressively enhanced the transport of In-ES, while transport of In-PH reached to plateau at 15°C. A states of equilibrium was not reached during 2 hr incubation at 22°C in In-ES. Uptake of In-PH reached to plateau after only 15 min of incubation. Distribution of In taken up by platelets in InES was 57% in cytosol and 27% in stroma, while in In-PH 69% in stroma and 22% in cytosol. 88% of In in cytosol was bound to lipids(46% in cholesterol and 27% in PS+PI). 82% of In in stroma was found in PS+PI fraction.The fact that the ratio of free In between the platelet water space and the outside medium after 30 min of incubation at up to 0.1 uM of In exceeded unity, suggests satura- , ble component of In transport prevails at this concentration in In-ES and In-PH. Kinetic constant could be calculated, Kt= 2nM, Vmax= 2.5 pmol/min/ml in In-ES, and Kt= InM, Vmax=0.7 pmol/min/ml in In-PH.Elution of In from radiolableled platelets in autologous plasma incubated at 37°C for 5 hr was less than 10% in the case of In-ES and 56% in the case of In-PH. Less than 3% of labeled-In was eluated from platelets in collagen-induced aggregation and 4-7% of In was eluated in thrombin-induced aggregation.Although 0.3% of ethanol and/or 6nM of oxine have no inhibitory effect of platelet aggregation, collagen-induced aggregation and release reaction of In-labeled platelet was impaired. 0.003% of polysorbate 80 itself abolished completely the aggregability of platelets by collagen or thrombin.It is concluded In-PH is unsuitable for platelet labeling. In-111 oxine also seems to have problems which Cr-51 has, i.e. inhomogenous distribution of In in a platelet population, elution of In from labeled platelets in circulation.

scholarly journals Pathways of Thrombin-Induced Aggregation and Release with Human and Rabbit Platelets

1977 ◽  
Author(s):  
R.L. Kinlough-Rathbone ◽  
D.W. Perry ◽  
M.A. Packham ◽  
J.F. Mustard
Keyword(s):  
Platelet Aggregation ◽  
Direct Effect ◽  
Thromboxane A2 ◽  
Human Platelets ◽  
The Third ◽  
Rabbit Platelets ◽  
Induced Aggregation

There are at least 3 mechanisms involved in thrombin-induced aggregation and release: (1) released ADP, (2) formation of thromboxane A2 and (3) a third mechanism(s). We have examined whether the third pathway is due to formation or release of a substance from platelets which affects other platelets. Washed human platelets were exposed to thrombin (2.5 u/ml) for 15 min at 37°C in the presence of indomethacin to block thromboxane A2 formation. Platelets were removed by centrifugation and the thrombin neutralized with hirudin or DFP. Addition of the superna te to washed human platelets prelabeled with 14C-serotonin caused platelet aggregation but release did not occur. Treatment of the supernate with apyrase, CP/CPK or dialysis abolished aggregation, indicating that the material was ADP. Thus, the mechanism by which thrombin induces aggregation and release with human platelets in the presence of agents which destroy ADP and block the formation of thromboxane A2 is a direct effect of thrombin on platelets and does not involve a substance freed from platelets. In contrast, when washed rabbit platelets were treated with thrombin in the presence of indomethacin and the released ADP was removed, material remained in the supernate which caused aggregation and release from washed rabbit platelets but was without effect on washed human platelets. The activity of this material (MW > 10,000) was not abolished by dialysis or boiling. Therefore rabbit platelets differ from human platelets because they have a mechanism in addition to released ADP, thromboxane A2 and the direct effect of thrombin on platelets that can cause aggregation and release.

Mariannaeapyrone -a New Inhibitor of Thromboxane A2 Induced Platelet Aggregation

2001 ◽  
Vol 56 (1-2) ◽  
pp. 106-110 ◽  
Author(s):  
Kerstin Fabian ◽  
Timm Anke ◽  
Olov Sterner
Keyword(s):  
Platelet Aggregation ◽  
Chemical Structure ◽  
Thromboxane A2 ◽  
Human Platelets ◽  
Selective Inhibitor ◽  
Spectroscopic Techniques ◽  
Fungal Metabolite ◽  
Antimicrobial Effects ◽  
The Common ◽  
Induced Aggregation

Abstract Mariannaeapyrone ((E)-2-(1,3,5,7-tetramethyl-5-nonenyl)-3,5-dimethyl-6-hydroxy-4H-pyran-4-one) is a new fungal metabolite isolated from fermentations of the common mycophilic deuteromycete Mariannaea elegans. The chemical structure of the 4-pyrone was determined by spectroscopic techniques. Mariannaeapyrone is a selective inhibitor of the thromboxane A2 induced aggregation of human platelets, whereas only weak cytotoxic and antimicrobial effects could be observed.

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