Trypsin and calcium ions elicit changes of the membrane potential in pig blood platelets

1978 ◽  
Vol 85 (3) ◽  
pp. 1233-1238 ◽  
Author(s):  
Ľudovít Varečka ◽  
Ladislav Kováč ◽  
Jozef Pogády
Keyword(s):  
Membrane Potential ◽  
Calcium Ions ◽  
Blood Platelets

On the Mechanism by which Cell Contact Induces the Release Reaction of Blood Platelets; the Effect of Cationic Polymers

1972 ◽  
Vol 27 (01) ◽  
pp. 121-133 ◽  
Author(s):  
P Massini ◽  
E. F Lüscher
Keyword(s):  
Human Blood ◽  
Calcium Ions ◽  
Blood Platelets ◽  
Cell Contact ◽  
Second Phase ◽  
Cationic Polymers ◽  
Release Reaction ◽  
Per Se ◽  
Human Blood Platelets

SummaryHuman blood platelets are aggregated by the basic polymers polylysine and DEAE- dextran. Under certain conditions a second phase of aggregation, concomitant with the release reaction, is elicited. The presence of ADP, calcium ions and a plasmatic cofactor within the primary aggregates are necessary for the induction of the release reaction. These experiments demonstrate that cell contact per se does not lead to a release reaction ; in order to become effective it must take place in the presence of ADP.

scholarly journals Alterations in The Trans-Membrane Potential of Human Blood Platelets in Response to Aggregating Stimuliow

1977 ◽  
Author(s):  
W. C. Horne ◽  
N. E. Larsen ◽  
E. R. Simons
Keyword(s):  
Membrane Potential ◽  
Blood Platelets ◽  
Human Platelets ◽  
Cyanine Dye ◽  
Secretory Cells ◽  
Coupling Mechanism ◽  
Stimulus Response ◽  
Low Concentrations ◽  
Dye Aggregation ◽  
Coupling Mechanisms

It has been suggested that the mechanism of response of platelets to aggregating stimuli is analogous to the stimulus-response coupling mechanisms of muscle and secretory cells. Because the coupling mechanisms of both types of systems involve changes in the trans-membrane potential of the stimulated cell, we have examined the membrane potential of human platelets to determine if the potential changes in response to aggregating agents. The membrane potential of gel-filtered platelets was monitored using a fluorescent cyanine dye. Aggregation was prevented to minimize artifacts due to changes in light scattering. The effects of ADP, thrombin, and collagen on the potential were examined. In response to ADP, the membrane rapidly became more negatively polarized. The response was concentration dependent, the minimum response occurring with 3x10-5M ADP. The response to thrombin was more complex. Low concentrations (0.01 U/ml) produced a change similar to that caused by ADP. Higher concentration (1–10 U/ml) led to a rapid decrease in the polarization of the membrane. When pre-formed collagen fibrils were added, in the presence of creatine Phosphokinase to destroy released ADP, no changein the potential was observed.Thus the platelet membrane potential changes in response to aggregating stimuli, supporting the hypothesis that stimulus of platelet aggregation is analogous to other stimulus-response coupling mechanisms. The change in potential is not a necessary step in the coupling mechanism. The different responses to specific agents indicate that the agents may trigger aggregation through different mechanisms.

VASOCONSTRICTION IN RESPONSE TO HUMAN PLATELET-VESSEL WALL INTERACTIONS

1987 ◽  
Author(s):  
J M Van Nueten ◽  
W J Janssens ◽  
F De Clerck
Keyword(s):  
Calcium Ions ◽  
Vessel Wall ◽  
Human Platelet ◽  
Blood Platelets ◽  
Thromboxane A2 ◽  
Period 2 ◽  
Acting In Concert ◽  
Human Blood Platelets ◽  
Serotonergic Antagonist ◽  
Wall Interactions

Human blood platelets, stimulated with thrombin, induced contractions of isolated basilar artery segments of the dog. These platelet-mediated vascular contractions were inhibited in a concentration-dependent way by flunarizine, a Ca2+-entry blocker, selective for vascular tissues. This inhibition increased gradually as a function of time after contact with flunarizine to reach its maximum after 60-90 min. Biochemical and pharmacological analyses, using the 5-HT2-serotonergic antagonist ritanserin, the thromboxane A2/prostaglandin endo-peroxide antagonist BM 13.177 and the fatty acid cyclo-oxygenase inhibitor suprofen, showed that 5-hydroxytryptamine and prostanoids (thromboxane A2, prostaglandine endoperoxides) were the main mediators involved. They further suggested amplification between 5-hydroxytryptamine and prostanoids at the vascular level.(1) Incubation period; (2) Inhibition of platelet-mediated vascular contractions.This study demonstrates that 5-hydroxytryptamine, acting in concert with thromboxane A2 and/or prostaglandine-endoper-oxides, is responsible for the vasoconstrictor effects of aggregating platelets. It further indicates that influx of calcium ions is involved in these vasoconstrictor responses.

Membrane potentials in an acanthocephalan worm (Macracanthorhynchus hirudinaceus)

Parasitology ◽  
1981 ◽  
Vol 83 (1) ◽  
pp. 33-41 ◽  
Author(s):  
D. M. Miller ◽  
B. S. Wong ◽  
T. T. Dunagan
Keyword(s):  
Smooth Muscle ◽  
Membrane Potential ◽  
Calcium Ions ◽  
Potassium Concentration ◽  
Sodium Concentration ◽  
Calcium Flux ◽  
Resting Membrane Potential ◽  
Free Medium ◽  
External Potassium ◽  
Macracanthorhynchus Hirudinaceus

SUMMARYThe resting membrane potential of the acanthocephalan rete system in Macracanthorhynchus hirudinaceus was −35±1·5 mV (n = 20) and was dependent upon the external potassium concentration. The membrane potential reached 0 mV when the external potassium concentration was 160 mM. Spontaneous spike potentials of 45 mV ± 10 were dependent on calcium flux. The membrane potential was depolarized by acetylcholine, potassium-free medium, calcium ions and chloride-free medium but not by changes in the external sodium concentration. Spontaneous potentials were increased in number by acetylcholine and calcium at concentrations above 3 mM, but were decreased in number by chloride- and calcium-free medium. Hence the rete system potentials are very similar to smooth muscle potentials in many respects.

Enzymes and Blood Clotting. II. Autoprothrombin C, Russell’s Viper Venom (Stypven), and Trypsin

1963 ◽  
Vol 09 (01) ◽  
pp. 062-073 ◽  
Author(s):  
John H Ferguson ◽  
Ella Gray Wilson Ennis
Keyword(s):  
Human Blood ◽  
Calcium Ions ◽  
Present Status ◽  
Blood Clotting ◽  
Blood Platelets ◽  
Accessory Factor ◽  
Russell’S Viper ◽  
Autoprothrombin C ◽  
Human Blood Platelets ◽  
Lipid Requirement

SummaryIn its dependence upon prothromboplastic phosphatide and calcium ions, in the conversion of prothrombin to thrombin, Autoprothrombin C is a thromboplastic enzyme. The only other demonstrated accessory factor is V, and any needs for VII, X, XI, or XII are ruled out by the present experiments, as were VIII or IX formerly. The lipid requirement may be satisfied by either phosphatidylserine (PS) or phosphatidylethanolamine (PE), purified from human blood platelets. Comparisons are made with Russell’s viper venom (“stypven”), and with trypsin. The trypsin potentiation of factors VII and X is prevented by pancreatic inhibitor (PI). However, when PI is added after this maximal potentiation, it is no longer inhibitory. The present status of knowledge concerning enzymes in relation to blood coagulation is discussed.

Binding of calcium ions to cell membrane isolated from bullfrog skeletal muscle

1964 ◽  
Vol 207 (2) ◽  
pp. 509-512 ◽  
Author(s):  
K. Koketsu ◽  
R. Kitamura ◽  
R. Tanaka
Keyword(s):  
Skeletal Muscle ◽  
Membrane Potential ◽  
Cell Membrane ◽  
Membrane Permeability ◽  
Calcium Ions ◽  
Cytoplasmic Membrane ◽  
Muscle Fibers ◽  
Potassium Ions ◽  
Chloroform Methanol ◽  
Sodium And Potassium

The membrane fragments of bullfrog skeletal muscle fibers were isolated by a modification of the method of Kono and Colowick (1961). Radiocalcium ions were bound to these isolated membrane fragments, and the binding of calcium ions was impeded by both sodium and potassium ions. The extractable portion of the isolated membrane fragments with chloroform-methanol mixture bound calcium ions whereas no appreciable binding of calcium ions was observed with the extracted residue. The results suggested that the binding of calcium ions takes place on the lipid or lipoprotein of the so-called cytoplasmic membrane which plays an important role in regulating the membrane permeability and the membrane potential.

scholarly journals Oxidative Damage of Blood Platelets Correlates with the Degree of Psychophysical Disability in Secondary Progressive Multiple Sclerosis

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Angela Dziedzic ◽  
Agnieszka Morel ◽  
Elzbieta Miller ◽  
Michal Bijak ◽  
Tomasz Sliwinski ◽  
...  
Keyword(s):  
Multiple Sclerosis ◽  
Membrane Potential ◽  
Mrna Expression ◽  
Mitochondrial Membrane Potential ◽  
Mitochondrial Membrane ◽  
Blood Platelets ◽  
Fold Increase ◽  
Past Research ◽  
Progressive Multiple Sclerosis ◽  
Nitrative Stress

The results of past research studies show that platelets are one of the main sources of reactive oxygen species (ROS) and reactive nitrogen species (RNS) to be found in the course of many pathological states. The aim of this study was to determine the level of oxidative/nitrative stress biomarkers in blood platelets obtained from multiple sclerosis (MS) patients (n=110) and to verify their correlation with the clinical parameters of the psychophysical disability of patients. The mitochondrial metabolism of platelets was assessed by measuring the intracellular production of ROS using the fluorescence method with DCFH-DA dye and by identification of changes in the mitochondrial membrane potential of platelets using the JC-1 dye. Moreover, we measured the mRNA expression for the gene encoding the cytochrome c oxidase subunit I (MTCO-1) and glyceraldehyde 3-phosphate dehydrogenase (GAPDH) in platelets and megakaryocytes using the RT-qPCR method, as well as the concentration of NADPH oxidase (NOX-1) by the ELISA method. Our results proved an increased level of oxidative/nitrative damage of proteins (carbonyl groups, 3-nitrotyrosine) (p<0.0001) and decreased level of -SH in MS (p<0.0001) and also a pronounced correlation between these biomarkers and parameters assessed by the Expanded Disability Status Scale and the Beck’s Depression Inventory. The application of fluorescence methods showed mitochondrial membrane potential disruption (p<0.001) and higher production of ROS in platelets from MS compared to control (p<0.0001). Our research has also confirmed the impairment of red-ox metabolism in MS, which was achieved by increasing the relative mRNA expression in platelets for the genes studied (2-fold increase for the MTCO-1 gene and 1.5-fold increase in GAPDH gene, p<0.05), as well as the augmented concentration of NOX-1 compared to control (p<0.0001). Our results indicate that the oxidative/nitrative damage of platelets is implicated in the pathophysiology of MS, which reflects the status of the disease.

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