CONTRACTIONS TO PLATELETS IN AORTAS OF CONTROL AND CHOLESTEROL-FED RABBITS

1987 ◽  
Author(s):  
T J Verbeuren ◽  
M J Van Diest ◽  
A G Herman
Keyword(s):  
Serotonin Receptor ◽  
Isometric Tension ◽  
Luminal Surface ◽  
Cholesterol Diet ◽  
Low Concentrations ◽  
Rabbit Platelets ◽  
Serotonin Receptor Antagonist ◽  
Evoked Contractions ◽  
New Zealand Rabbits

Atherosclerotic aortas obtained from cholesterol-fed rabbits show a decreased responsiveness to noradrenaline, an increased responsiveness to low concentrations of serotoninand an unaltered responsiveness to prostaglandins. In vitro contractions induced by aggregating platelets are largely due to serotonin liberated during the aggregation. The present study was designed to compare the contractile responses to aggregating platelets inaortas obtained from control and cholesterol-fed rabbits.Male New Zealand rabbits were fed either a control or a 0.3% cholesterol diet during 16 weeks. Macroscopic and microscopic examination of the luminal surface of the aortas obtained from these animals revealed a substantial amount of fatty streaks in the tissuesobtained from the cholesterol-fed rabbits. Segments of the aortic arch of the rabbits were then mounted in organ chambers for isometric tension recording.In both the control and the atherosclerotic aortas increasing concentrations of platelets evoked contractions; the contractions obtained with the lower concentrations of platelets were significantly greater in the atherosclerotic tissues. The maximal responses and the ED50-values were comparable in both groups of blood vessels. No significant differences were observed when platelets obtained from control or hypercholesterolemic rabbits were compared. In the control and the atherosclerotic aortas the thromboxane receptorantagonist BM13505 at 2 x 10-5M did not significantly affect the contractionsto platelets obtained from either control or cholesterol-fed rabbits. The serotonin receptor antagonist ketanserin at 5 x 10-8M nearly abolished the responses to platelets in bothgroups of aortas.These experiments illustrate that (1) thecontractions induced by rabbit platelets in control and atherosclerotic aortas are mediated by serotonin and (2) the responses to platelets, as those to serotonin, are augmented in the atherosclerotic preparations.

In Vitro Effects of Ethanol on Rabbit Platelet Aggregation, Secretion of Granule Contents, and Cyclic AMP Levels in the Presence of Prostacyclin

1989 ◽  
Vol 61 (02) ◽  
pp. 254-258 ◽  
Author(s):  
Margaret L Rand ◽  
Peter L Gross ◽  
Donna M Jakowec ◽  
Marian A Packham ◽  
J Fraser Mustard
Keyword(s):  
Cyclic Amp ◽  
Inhibitory Effect ◽  
Rabbit Platelet ◽  
Inhibitory Effects ◽  
Low Concentrations ◽  
Rabbit Platelets ◽  
High Concentrations ◽  
In Vitro Effects ◽  
Aggregation Of Platelets

SummaryEthanol, at physiologically tolerable concentrations, inhibits platelet responses to low concentrations of collagen or thrombin, but does not inhibit responses of washed rabbit platelets stimulated with high concentrations of ADP, collagen, or thrombin. However, when platelet responses to high concentrations of collagen or thrombin had been partially inhibited by prostacyclin (PGI2), ethanol had additional inhibitory effects on aggregation and secretion. These effects were also observed with aspirin- treated platelets stimulated with thrombin. Ethanol had no further inhibitory effect on aggregation of platelets stimulated with ADP, or the combination of ADP and epinephrine. Thus, the inhibitory effects of ethanol on platelet responses in the presence of PGI2 were very similar to its inhibitory effects in the absence of PGI2, when platelets were stimulated with lower concentrations of collagen or thrombin. Ethanol did not appear to exert its inhibitory effects by increasing cyclic AMP above basal levels and the additional inhibitory effects of ethanol in the presence of PGI2 did not appear to be brought about by further increases in platelet cyclic AMP levels.

scholarly journals The Whisking Rhythm Generator: A Novel Mammalian Network for the Generation of Movement

2007 ◽  
Vol 97 (3) ◽  
pp. 2148-2158 ◽  
Author(s):  
Nathan P. Cramer ◽  
Ying Li ◽  
Asaf Keller
Keyword(s):  
Firing Rate ◽  
Serotonin Receptor ◽  
Central Pattern Generators ◽  
Rhythm Generator ◽  
Low Concentrations ◽  
Rhythmic Firing ◽  
Pattern Generators ◽  
Cortical Inputs

Using the rat vibrissa system, we provide evidence for a novel mechanism for the generation of movement. Like other central pattern generators (CPGs) that underlie many movements, the rhythm generator for whisking can operate without cortical inputs or sensory feedback. However, unlike conventional mammalian CPGs, vibrissa motoneurons (vMNs) actively participate in the rhythmogenesis by converting tonic serotonergic inputs into the patterned motor output responsible for movement of the vibrissae. We find that, in vitro, a serotonin receptor agonist, α-Me-5HT, facilitates a persistent inward current (PIC) and evokes rhythmic firing in vMNs. Within each motoneuron, increasing the concentration of α-Me-5HT significantly increases the both the magnitude of the PIC and the motoneuron's firing rate. Riluzole, which selectively suppresses the Na+ component of PICs at low concentrations, causes a reduction in both of these phenomena. The magnitude of this reduction is directly correlated with the concentration of riluzole. The joint effects of riluzole on PIC magnitude and firing rate in vMNs suggest that the two are causally related. In vivo we find that the tonic activity of putative serotonergic premotoneurons is positively correlated with the frequency of whisking evoked by cortical stimulation. Taken together, these results support the hypothesized novel mammalian mechanism for movement generation in the vibrissa motor system where vMNs actively participate in the rhythmogenesis in response to tonic drive from serotonergic premotoneurons.

scholarly journals Azologization of serotonin 5-HT3 receptor antagonists

2019 ◽  
Vol 15 ◽  
pp. 780-788 ◽  
Author(s):  
Karin Rustler ◽  
Galyna Maleeva ◽  
Piotr Bregestovski ◽  
Burkhard König
Keyword(s):  
Serotonin Receptor ◽  
Antagonistic Activity ◽  
Ionotropic Receptor ◽  
Photochromic Properties ◽  
Spatiotemporal Resolution ◽  
Chemical Structures ◽  
In Vitro Characterization ◽  
Serotonin Receptor Antagonist ◽  
G Protein Coupled

The serotonin 5-hydroxytryptamine 3 receptor (5-HT3R) plays a unique role within the seven classes of the serotonin receptor family, as it represents the only ionotropic receptor, while the other six members are G protein-coupled receptors (GPCRs). The 5-HT3 receptor is related to chemo-/radiotherapy provoked emesis and dysfunction leads to neurodevelopmental disorders and psychopathologies. Since the development of the first serotonin receptor antagonist in the early 1990s, the range of highly selective and potent drugs expanded based on various chemical structures. Nevertheless, on-off-targeting of a pharmacophore’s activity with high spatiotemporal resolution as provided by photopharmacology remains an unsolved challenge bearing additionally the opportunity for detailed receptor examination. In the presented work, we summarize the synthesis, photochromic properties and in vitro characterization of azobenzene-based photochromic derivatives of published 5-HT3R antagonists. Despite reported proof of principle of direct azologization, only one of the investigated derivatives showed antagonistic activity lacking isomer specificity.

Selective Targeting of Leukemic Over Normal Stem Cells by the Serotonin Receptor Antagonist SB-216641

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 1884-1884
Author(s):  
Alissa R. Kahn ◽  
Kimberly A. Hartwell ◽  
Peter G. Miller ◽  
Benjamin L. Ebert ◽  
Todd R. Golub ◽  
...  
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Cell Lines ◽  
Serotonin Receptor ◽  
Leukemic Cells ◽  
Leukemic Stem Cells ◽  
Nsg Mice ◽  
Cell Kill ◽  
Serotonin Receptor Antagonist

Abstract Abstract 1884 Acute myeloid leukemia (AML) is a common and aggressive hematologic malignancy affecting both children and adults which continues to have high mortality rates as well as high morbidity from toxic therapies. New treatments are needed to improve cure rates and decrease morbidity. A niche-based high throughput screen done in a murine system identified candidate small molecules potentially toxic to leukemic stem cells (LSCs) while sparing normal hematopoietic stem cells (HSCs) and bone marrow stroma (Hartwell KA, Miller, PG et al., in preparation). One such compound, SB-216641, demonstrated dose-dependent activity against leukemia in both a cell autonomous and non-autonomous manner, by modifying niche–based support. SB-216641 is a selective serotonin receptor antagonist specific for the 5-HT1B receptor, highlighting a pathway not previously investigated in the context of AML or leukemia stem cell biology. We examined the effects of this candidate small molecule on 7 human primary AML samples. CD34+ cells were isolated from these samples with immunomagnetic beads. Using the colony forming assay to assess kill of progenitor cells, all samples had ≥99% cell kill at 25 μM (10 times the IC-50 found in the murine system). We then assessed the compound's effect on LSCs using the cobblestone area forming cell (CAFC) assay, a standard in vitro stem cell assay. The leukemic cells were pulse treated for 18 hours and washed to remove residual SB-216641 prior to placement on MS-5 murine stroma and therefore only the direct effect on the leukemic cells was measured in this assay. CAFCs were read out at week 5, or week 2 when the sample was FLT3-ITD+ (Chung KY et al, Blood 2005, Vol 105, 77–84). We first tested five samples at 25 μM. All samples formed cobblestone areas in the control setting (46–200 CAFCs/106 cells plated). Four samples had no CAFC formation with SB-216641 and the remaining sample had >95% decrease in CAFC formation. We then performed serial dilutions using the CAFC assay in the human primary samples as well as in HSCs derived from cord blood to obtain the IC-50 for human AML and to ensure that our differential cell kill of LSCs versus normal HSCs held true in the human samples. IC-50 for the human primary leukemias was found to be 630 nanomolar and at 10 μM all leukemic samples were fully killed with 100% survival of normal human HSCs [see figure 1]. As a confirmatory study, using HL60 and U937 human AML cell lines transduced with GFP-luciferase, 500 cells were preincubated with SB-216641 at 25 μM or DMSO control and then injected IV into Nod Scid IL2R-gamma null (NSG) mice and imaged at 5 weeks. In both cell lines, the control mice had engraftment and the mice that received treated cells had no engraftment. HL60 cells were then preincubated with SB-216641 at lower doses (10 and 5 μM) and injected into NSG mice and imaged at 3 weeks. Again, the control mice had engraftment and the mice that received treated cells had no engraftment.Figure 1.Figure 1. 5-HT1B receptor antagonists have not previously been known to be active against AML or leukemic stem cells. Some hematopoietic cells including platelets express serotonin receptors and T-cells specifically have been found to express the 5-HT1b receptor. Selective 5-HT1B receptor antagonists have found to have apoptotic effects in vitro against cell lines of other cancers and may be involved in MAP kinase and P13K/Akt signaling pathways. SB-216641 is a highly promising compound which warrants further investigation. Its high toxicity to LSCs and sparing of normal HSCs make it appealing for possible clinical use in the future. Disclosures: No relevant conflicts of interest to declare.

Human thoracic duct in vitro: diameter-tension properties, spontaneous and evoked contractile activity

2010 ◽  
Vol 299 (3) ◽  
pp. H811-H818 ◽  
Author(s):  
Niklas Telinius ◽  
Nanna Drewsen ◽  
Hans Pilegaard ◽  
Henrik Kold-Petersen ◽  
Marc de Leval ◽  
...  
Keyword(s):  
Thoracic Duct ◽  
Contractile Activity ◽  
Isometric Tension ◽  
Lymph Vessel ◽  
Internal Diameter ◽  
Activity Maximum ◽  
Low Concentrations ◽  
Wide Range ◽  
Tension Properties

The current study characterizes the mechanical properties of the human thoracic duct and demonstrates a role for adrenoceptors, thromboxane, and endothelin receptors in human lymph vessel function. With ethical permission and informed consent, portions of the thoracic duct (2–5 cm) were resected and retrieved at T7–T9 during esophageal and cardia cancer surgery. Ring segments (2 mm long) were mounted in a myograph for isometric tension (N/m) measurement. The diameter-tension relationship was established using ducts from 10 individuals. Peak active tension of 6.24 ± 0.75 N/m was observed with a corresponding passive tension of 3.11 ± 0.67 N/m and average internal diameter of 2.21 mm. The equivalent active and passive transmural pressures by LaPlace's law were 47.3 ± 4.7 and 20.6 ± 3.2 mmHg, respectively. Subsequently, pharmacology was performed on rings from 15 ducts that were normalized by stretching them until an equivalent pressure of 21 mmHg was calculable from the wall tension. At low concentrations, norepinephrine, endothelin-1, and the thromboxane-A2 analog U-46619 evoked phasic contractions (analogous to lymphatic pumping), whereas at higher contractions they induced tonic activity (maximum tension values of 4.46 ± 0.63, 5.90 ± 1.4, and 6.78 ± 1.4 N/m, respectively). Spontaneous activity was observed in 44% of ducts while 51% of all the segments produced phasic contractions after agonist application. Acetylcholine and bradykinin relaxed norepinephrine preconstrictions by ∼20% and ∼40%, respectively. These results demonstrate that the human thoracic duct can develop wall tensions that permit contractility to be maintained across a wide range of transmural pressures and that isolated ducts contract in response to important vasoactive agents.

Kinetics of Various 99mTc-Sn-Pyrophosphate Compounds in the Rat

1977 ◽  
Vol 16 (04) ◽  
pp. 157-162 ◽  
Author(s):  
C. Schümichen ◽  
B. Mackenbrock ◽  
G. Hoffmann
Keyword(s):  
Normal Saline ◽  
Half Life ◽  
Compound A ◽  
Short Half Life ◽  
Low Concentrations ◽  
The Stability ◽  
Kinetics Of ◽  
In Vitro Stability

SummaryThe bone-seeking 99mTc-Sn-pyrophosphate compound (compound A) was diluted both in vitro and in vivo and proved to be unstable both in vitro and in vivo. However, stability was much better in vivo than in vitro and thus the in vitro stability of compound A after dilution in various mediums could be followed up by a consecutive evaluation of the in vivo distribution in the rat. After dilution in neutral normal saline compound A is metastable and after a short half-life it is transformed into the other 99mTc-Sn-pyrophosphate compound A is metastable and after a short half-life in bone but in the kidneys. After dilution in normal saline of low pH and in buffering solutions the stability of compound A is increased. In human plasma compound A is relatively stable but not in plasma water. When compound B is formed in a buffering solution, uptake in the kidneys and excretion in urine is lowered and blood concentration increased.It is assumed that the association of protons to compound A will increase its stability at low concentrations while that to compound B will lead to a strong protein bond in plasma. It is concluded that compound A will not be stable in vivo because of a lack of stability in the extravascular space, and that the protein bond in plasma will be a measure of its in vivo stability.

LY53857, a 5HT2 Receptor Antagonist, Delays Occlusion and Inhibits Platelet Aggregation in a Rabbit Model of Carotid Artery Occlusion

1991 ◽  
Vol 66 (03) ◽  
pp. 355-360 ◽  
Author(s):  
Harve C Wilson ◽  
William Coffman ◽  
Anne L Killam ◽  
Marlene L Cohen
Keyword(s):  
Electrical Stimulation ◽  
Platelet Aggregation ◽  
Carotid Artery ◽  
Receptor Antagonist ◽  
Artery Occlusion ◽  
Carotid Artery Occlusion ◽  
Rabbit Platelet ◽  
Rabbit Platelets ◽  
5Ht2 Receptor

SummaryThe present study was designed to evaluate the effectiveness of the ergoline 5HT2 receptor antagonist, LY53857 in a rabbit model of vascular arterial occlusion. LY53857 (1 and 10 εM) inhibited serotonin amplified platelet aggregation responses to threshold concentrations of ADP in rabbit platelets in vitro. LY53857 (1 εM) not only inhibited the serotonin component of rabbit platelet aggregation, but also inhibited in vitro aggregation induced by ADP (48.7 ± 16.7% inhibition), collagen (76.1 ± 15.9% inhibition) and U46619 (65.2 ± 12.3% inhibition). The effectiveness of this ergoline 5HT2 receptor antagonist in blocking aggregation to ADP, collagen and U46619 may be related to its ability to inhibit a serotonin component of platelet aggregation since rabbit platelets possess high concentrations of serotonin that may be released during aggregation produced by other agents. Based on the effectiveness of LY53857 to inhibit rabbit platelet aggregation, we explored the ability of LY53857 to extend the time to carotid artery occlusion in rabbits following electrical stimulation of the artery. Reproducible carotid artery occlusion was induced in rabbits by moderate stenosis coupled to arterial cross clamping, followed by electrical stimulation. With this procedure, occlusion occurred at 47.0 ± 7 min (n = 30) after initiation of the electrical stimulation. Animals pretreated with LY53857 (50 to 500 εg/kg i.v.) showed a delay in the time to carotid artery occlusion (at 100 εg/kg i.v. occlusion time extended to 164 ± 16 min). Furthermore, ex vivo platelet aggregation from animals treated with LY53857 (300 εg/kg i.v.) resulted in 40.5% inhibition of platelet aggregation in response to the combination of ADP (1 εM) and serotonin (1 εM). These studies document the ability to obtain reproducible arterial occlusion in the rabbit and showed that intravenously administered LY53857 prolonged the time to carotid artery occlusion. Prolongation of carotid artery occlusion time was accompanied by inhibition of serotonin-amplified ADP-induced aggregation in rabbit platelets, an effect observed both in vitro and ex vivo. Thus, the rabbit is a useful model for studying the effectiveness of 5HT2 receptor antagonists in prolonging vascular occlusion induced by insult of the carotid artery.

Effects of Bupranolol, a New β-Blocker, on Platelet Functions of Rabbit and Human in Vitro

1976 ◽  
Vol 36 (02) ◽  
pp. 376-387 ◽  
Author(s):  
Teruhiko Umetsu ◽  
Kazuko Sanai ◽  
Tadakatsu Kato
Keyword(s):  
Platelet Aggregation ◽  
Platelet Adhesion ◽  
Human Platelets ◽  
Rabbit Platelet ◽  
Rabbit Platelets ◽  
Β Blocker ◽  
Platelet Aggregates ◽  
Induced Aggregation ◽  
Platelet Functions

SummaryThe effects of bupranolol, a new β-blocker, on platelet functions were investigated in vitro in rabbits and humans as compared with propranolol, a well-known β-blocker. At first, the effect of adrenaline on ADP-induced rabbit platelet aggregation was studied because adrenaline alone induces little or no aggregation of rabbit platelets. Enhancement of ADP-induced rabbit platelet aggregation by adrenaline was confirmed, as previously reported by Sinakos and Caen (1967). In addition the degree of the enhancement was proved to be markedly affected by the concentration of ADP and to increase with decreasing concentration of ADP, although the maximum aggregation (percent) was decreased.Bupranolol and propranolol inhibited the (adrenaline-ADP-)induced aggregation of rabbit platelets, bupranolol being approximately 2.4–3.2 times as effective as propranolol. Bupranolol stimulated the disaggregation of platelet aggregates induced by a combination of adrenaline and ADP, but propranolol did not. Platelet adhesion in rabbit was also inhibited by the β-blockers and bupranolol was more active than propranolol. With human platelets, aggregation induced by adrenaline was inhibited by bupranolol about 2.8–3.3 times as effectively as propranolol.From these findings. We would suggest that bupranolol might be useful for prevention or treatment of thrombosis.

Aggregation of Cat Platelets in Vitro

1970 ◽  
Vol 23 (03) ◽  
pp. 601-620 ◽  
Author(s):  
Th. B Tschopp
Keyword(s):  
Adenosine Monophosphate ◽  
Blood Collection ◽  
Base Line ◽  
Reversible Aggregation ◽  
Low Concentrations ◽  
Irreversible Aggregation ◽  
High Concentrations ◽  
Two Phases ◽  
Improved Technique

SummaryAggregation of cat platelets in the citrated plasma is examined by means of Born’s absorptiometer. A marked tendency of the platelets of this species to spontaneous aggregation necessitated first of all the development of an improved technique of blood collection.A hypothesis according to which 5-HT is released from the platelets, explains the absence of oscillations on the base line of the absorptiometer, the absence of platelet swelling, when ADP is added, and the effect of stirring on the aggregation curves in cat PRP. The average volume of cat platelets amounts to 10.46 μ3 when directly fixed in the blood, when fixed from PRP to 12.17 μ3, when fixed from stirred PRP to 13.51 μ3.In low concentrations (0.3-2 μM) ADP produce reversible aggregation; in narrowly restricted, individually dissimilar mean concentrations irreversible aggregation in two phases and in high concentrations, irreversible aggregation in one phase. Like ADP serotonin produces 2 phase irreversible aggregation in concentrations of 3-10 μM, but unlike ADP, the aggregation velocity decreases again with high 5-HT concentrations (>100 μM). Adrenaline does not produce aggregation and it is likely that adenosine and adenosine monophosphate inhibit the aggregation by serotonin but not by ADP. Species differences in the aggregation of human, rabbit and cat platelets are discussed.

DEVELOPMENT OF APPROACHES FOR DETECTION OF GENOME-INTEGRATED PROVIRAL DNA OF THE HUMAN IMMUNODEFICIENCY VIRUS (HIV-1) IN ULTRA LOW CONCENTRATIONS USING THE CRISPR/CAS SYSTEM

2020 ◽  
Author(s):  
M.A. Tyumentseva ◽  
◽  
A.I. Tyumentsev ◽  
V.G. Akimkin ◽  
◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Health Monitoring ◽  
Biological Samples ◽  
Proviral Dna ◽  
Guide Rnas ◽  
Ribonucleoprotein Complexes ◽  
Low Concentrations ◽  
Immunodeficiency Virus ◽  
Hiv 1

For the effective functioning of supervisory and health monitoring services, it is necessary to introduce modern molecular technologies into their practice. Therefore, the task of developing new effective methods for detecting pathogen, for example HIV, based on CRISPR/CAS genome editing systems, remains urgent. In the present work, guide RNAs and specific oligonucleotides were developed for preliminary amplification of highly conserved regions of the HIV-1 genome. The developed guide RNAs make it possible to detect single copies of HIV-1 proviral DNA in vitro as part of CRISPR/CAS ribonucleoprotein complexes in biological samples after preliminary amplification.

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