ATP induces contraction of cultured brain capillary pericytes, via activation of P2Y type purinergic receptors

2020 ◽  
Author(s):  
Sofie Hørlyck ◽  
Changsi Cai ◽  
Hans C Helms ◽  
Martin Lauritzen ◽  
Birger Brodin
Keyword(s):  
Intracellular Calcium ◽  
Purinergic Receptors ◽  
Calcium Release ◽  
Purinergic Receptor ◽  
Cytosolic Calcium ◽  
Receptor Activation ◽  
Confocal Imaging ◽  
Inositol Triphosphate ◽  
Brain Capillary

Brain capillary pericytes have been suggested to play a role in the regulation of cerebral blood-flow under physiological and pathophysiological conditions. ATP has been shown to cause constriction of capillaries under ischemic conditions and suggested to be involved in the "no-reflow" phenomenon. In order to investigate the effects of extracellular ATP on pericyte cell contraction, we studied purinergic receptor activation of cultured bovine brain capillary pericytes. We measured [Ca2+]i-responses to purinergic agonists with the fluorescent indicators fura-2 and Cal-520 and estimated contraction of pericytes as relative change in cell area, using real-time confocal imaging. Addition of ATP caused an increase in cytosolic calcium and contraction of the brain capillary pericytes, both reversible and inhibited by a purinergic receptor antagonist PPADS. Furthermore, we demonstrated that ATP-induced contraction could be eliminated by intracellular calcium-chelation with BAPTA, indicating that the contraction was mediated via purinergic P2 -type receptor-mediated [Ca2+]i-signaling. ATP stimulation induced inositol triphosphate signaling, consistent with the notion of P2Y receptor activation. Receptor profiling studies demonstrated presence of P2Y1 and P2Y2 receptors, using ATP, UTP, ADP and the subtype specific agonists MRS2365 (P2Y1) and 2-thio-UTP (P2Y2)). Addition of specific P2X agonists only caused a [Ca2+]i increase at high concentrations, attributed to activation of inositol triphosphate signaling. Our results suggest that contraction of brain capillary pericytes in vitro by activation of P2Y type purinergic receptors is caused by intracellular calcium release. This adds more mechanistic understanding to the role of pericytes in vessel constriction, and points towards P2Y receptors as potential therapeutic targets.

Adenosine nucleotides in bile

1996 ◽  
Vol 270 (2) ◽  
pp. G246-G252 ◽  
Author(s):  
R. S. Chari ◽  
S. M. Schutz ◽  
J. E. Haebig ◽  
G. H. Shimokura ◽  
P. B. Cotton ◽  
...  
Keyword(s):  
Purinergic Receptors ◽  
Purinergic Receptor ◽  
Receptor Activation ◽  
Hepatoma Cells ◽  
Human Bile ◽  
Nucleotide Release ◽  
Cholangiocarcinoma Cell ◽  
Adenosine Nucleotides ◽  
Vitro Model

Activation of purinergic receptors by ATP stimulates Cl- efflux in biliary epithelial cells. To determine whether purinergic agonists are present under physiological conditions, we have assayed mammalian bile for nucleotides and assessed whether hepatoma and cholangiocarcinoma cell lines are capable of nucleotide release. Bile samples were collected from human, rat, and pig donors and assayed for nucleotide concentrations by luminometry. ATP, ADP, and AMP were present in bile from each species, and the average total nucleotide concentration in human bile was 5.21 +/- 0.91 microM (n = 16). In an in vitro model of HTC rat hepatoma cells or Mz-ChA-1 cholangiocarcinoma cells on a superfused column, nucleotides were present in the effluent from each cell type. Addition of alpha, beta-methyleneadenosine 5'-diphosphate (50 microM) to inhibit 5'-nucleotidase activity increased AMP concentrations two- to threefold. Exposure to forskolin (100 microM) or ionomycin (2 microM) stimulated nucleotide release from cholangiocarcinoma but not hepatoma cells. These studies indicate that adenosine nucleotides are present in bile in concentrations sufficient to activate purinergic receptors. Purinergic receptor activation by local nucleotide release might constitute an autocrine and/or paracrine mechanism for modulation of biliary secretion.

scholarly journals Pro- and anti-inflammatory macrophages express a sub-type specific purinergic receptor profile

2021 ◽  
Author(s):  
J. Merz ◽  
A. Nettesheim ◽  
S. von Garlen ◽  
P. Albrecht ◽  
B. S. Saller ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Purinergic Receptors ◽  
Purinergic Receptor ◽  
Receptor Activation ◽  
Extracellular Nucleotides ◽  
M1 Macrophages ◽  
Murine Bone Marrow ◽  
Receptor Profile ◽  
Anti Inflammatory

AbstractExtracellular nucleotides act as danger signals that orchestrate inflammation by purinergic receptor activation. The expression pattern of different purinergic receptors may correlate with a pro- or anti-inflammatory phenotype. Macrophages function as pro-inflammatory M1 macrophages (M1) or anti-inflammatory M2 macrophages (M2). The present study found that murine bone marrow-derived macrophages express a unique purinergic receptor profile during in vitro polarization. As assessed by real-time polymerase chain reaction (PCR), Gαs-coupled P1 receptors A2A and A2B are upregulated in M1 and M2 compared to M0, but A2A 15 times higher in M1. The ionotropic P2 receptor P2X5 is selectively upregulated in M1- and M2-polarized macrophages. P2X7 is temporarily expressed in M1 macrophages. Metabotropic P2Y receptors showed a distinct expression profile in M1 and M2-polarized macrophages: Gαq coupled P2Y1 and P2Y6 are exclusively upregulated in M2, whereas Gαi P2Y13 and P2Y14 are overexpressed in M1. This consequently leads to functional differences between M1 and M2 in response to adenosine di-phosphate stimulation (ADP): In contrast to M1, M2 showed increased cytoplasmatic calcium after ADP stimulation. In the present study we show that bone marrow-derived macrophages express a unique repertoire of purinergic receptors. We show for the first time that the repertoire of purinergic receptors is highly flexible and quickly adapts upon pro- and anti-inflammatory macrophage differentiation with functional consequences to nucleotide stimulation.

scholarly journals Orientia tsutsugamushi Inhibits Apoptosis of Macrophages by Retarding Intracellular Calcium Release

2002 ◽  
Vol 70 (8) ◽  
pp. 4692-4696 ◽  
Author(s):  
Mee-Kyung Kim ◽  
Seung-Yong Seong ◽  
Ju-Young Seoh ◽  
Tae-Hee Han ◽  
Hyeon-Je Song ◽  
...  
Keyword(s):  
Intracellular Calcium ◽  
Calcium Concentration ◽  
Calcium Release ◽  
Cytosolic Calcium ◽  
Orientia Tsutsugamushi ◽  
Cytosolic Calcium Concentration ◽  
Infected Cells ◽  
Intracellular Calcium Release ◽  
Calcium Redistribution ◽  
In Cells

ABSTRACT Orientia tsutsugamushi shows both pro- and antiapoptotic activities in infected vertebrate cells. Apoptosis of THP-1 cells induced by beauvericin was inhibited by O. tsutsugamushi infection. Beauvericin-induced calcium redistribution was significantly reduced and retarded in cells infected with O. tsutsugamushi. Antiapoptotic activities of O. tsutsugamushi in infected cells are most probably due to inhibition of the increase in the cytosolic calcium concentration.

scholarly journals Protein kinase C- and calcium-regulated pathways independently synergize with Gi pathways in agonist-induced fibrinogen receptor activation

2002 ◽  
Vol 368 (2) ◽  
pp. 535-543 ◽  
Author(s):  
Todd M. QUINTON ◽  
Soochong KIM ◽  
Carol DANGELMAIER ◽  
Robert T. DORSAM ◽  
Jianguo JIN ◽  
...  
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Intracellular Calcium ◽  
Phospholipase C ◽  
Calcium Release ◽  
Receptor Activation ◽  
Dense Granule ◽  
Fibrinogen Receptor ◽  
Kinase C ◽  
Induced Aggregation

Platelet fibrinogen receptor activation is a critical step in platelet plug formation. The fibrinogen receptor (integrin αIIbβ3) is activated by agonist-mediated Gq stimulation and resultant phospholipase C activation. We investigated the role of downstream signalling events from phospholipase C, namely the activation of protein kinase C (PKC) and rise in intracellular calcium, in agonist-induced fibrinogen receptor activation using Ro 31-8220 (a PKC inhibitor) or dimethyl BAPTA [5,5′-dimethyl-bis-(o-aminophenoxy)ethane-N,N,N′,N′-tetra-acetic acid], a high-affinity calcium chelator. All the experiments were performed with human platelets treated with aspirin, to avoid positive feedback from thromboxane A2. In the presence of Ro 31-8220, platelet aggregation caused by U46619 was completely inhibited while no effect or partial inhibition was seen with ADP and the thrombin-receptor-activating peptide SFLLRN, respectively. In the presence of intracellular dimethyl BAPTA, ADP- and U46619-induced aggregation and anti-αIIbβ3 antibody PAC-1 binding were completely abolished. However, similar to the effects of Ro 31-8220, dimethyl BAPTA only partially inhibited SFLLRN-induced aggregation, and was accompanied by diminished dense-granule secretion. When either PKC activation or intracellular calcium release was abrogated, aggregation and fibrinogen receptor activation with U46619 or SFLLRN was partially restored by additional selective activation of the Gi signalling pathway. In contrast, when both PKC activity and intracellular calcium increase were simultaneously inhibited, the complete inhibition of aggregation that occurred in response to either U46619 or SFLLRN could not be restored with concomitant Gi signalling. We conclude that, while the PKC- and calcium-regulated signalling pathways are capable of inducing activating fibrinogen receptor independently and that each can synergize with Gi signalling to cause irreversible fibrinogen receptor activation, both pathways act synergistically to effect irreversible fibrinogen receptor activation.

A mathematical model of cytosolic calcium dynamics in human umbilical vein endothelial cells

1996 ◽  
Vol 270 (5) ◽  
pp. C1556-C1569 ◽  
Author(s):  
T. F. Wiesner ◽  
B. C. Berk ◽  
R. M. Nerem
Keyword(s):  
Mathematical Model ◽  
Endothelial Cells ◽  
Calcium Release ◽  
Umbilical Vein ◽  
Kinetic Equations ◽  
Cytosolic Calcium ◽  
Receptor Activation ◽  
Free Calcium ◽  
Human Umbilical Vein ◽  
Umbilical Vein Endothelial Cells

Important among the responses of endothelial cells are cytosolic free calcium transients. These transients are mediated by several factors, including blood-borne agonists, extracellular calcium, and fluid-imposed shear forces. The transients are characterized by a rapid rise followed by a plateau phase. A base mathematical model is presented that reasonably reproduces the measured calcium transient in cultured human umbilical vein endothelial cells responding to thrombin. Kinetic equations for receptor activation and calcium mobilization comprise the model. A graded response of intracellular free calcium to increasing concentrations of agonist is predicted. Also predicted is the elevation of the peak value and the plateau level by steady nonspecific leak of calcium across the plasma membrane. The influences of capacitative calcium entry, calcium-induced calcium release, and buffering by cytosolic proteins are investigated parametrically. The model predicts significant depletion of cellular calcium in response to agonist stimulation.

O-152 Investigation of the relationship of sperm motility and Kisspeptin in subfertile men

2021 ◽  
Vol 36 (Supplement_1) ◽  
Author(s):  
A Kocaman ◽  
B Ayas
Keyword(s):  
Gene Expression ◽  
Intracellular Calcium ◽  
Sperm Motility ◽  
Laser Scanning ◽  
Calcium Release ◽  
Expression Levels ◽  
Significant Difference ◽  
Motility Parameters ◽  
Gene Expression Levels

Abstract Study question Does kisspeptin administration affect the motility parameters in sperm samples of subfertile cases? Summary answer Kisspeptin administration significantly increased gene expression levels related with sperm motility as well as intracellular calcium concentrations. What is known already Sperm motility problems are among the most important causes of male infertility. In recent years, a peptide named kisspeptin has been discovered that may have effects on sperm motility. Kisspeptin is known to trigger calcium release in hypothalamic neurons. In addition, kisspeptin administration increased sperm progressive motility in studies conducted on normozoospermic individuals. Furthermore, it is suggested that kisspeptin protein in seminal plasma is positively associated with semen quality. However, there is no evidence that how kisspeptin can affect sperm in men with infertility problems. Study design, size, duration This basic research study was an in vitro experimental approach involving the use of semen samples from an infertil cases between September to December in 2020. 40 men were included in both control and experimental groups. Participants/materials, setting, methods All analyses were performed on semen samples from 10 normozoospermic (NZ), 10 asthenozoospermic (AZ), 10 oligoasthenozoospermic (OAZ) and 10 oligoastenoteratozoospermic (OATZ) men, aging between (21-40) years. Basal serum and seminal kisspeptin levels were analyzed by ELISA. Sperm were divided into two groups. Kisspeptin-13 administered in vitro. KISS1, KISS1R, CATSPER1, AKAP4 gene expressions analyzed by qRT-PCR using 2−ΔΔCt algorithm. Intracellular calcium concentration was determined with floresence spectroflurometer and laser scanning confocal microscope. Main results and the role of chance The serum kisspeptin level of NZ was significantly higher than other groups (p < 0.05). The semen kisspeptin level was significantly higher than OAZ and OATZ (p < 0.05), but not in NZ (p > 0.05). Also, KISS1 gene expression was higher in AZ compared to other groups (p < 0.05). Biochemical and gene expression analysis of kisspeptin were consistent with each other. There was a significant increase in the expression of CATSPER1 gene in AZ compared to other groups (p < 0.05). Also, AKAP4 gene expression was significantly higher in OATZ compared to other groups (p < 0.05). No significant difference was documented for the expression of KISS1R (p > 0.05). Intracellular calcium was significantly increased in AZ and NZ after kisspeptin administration. The intracellular calcium increase is consistent with increased CATSPER1 gene expression levels in AZ. Kisspeptin administration may have a significant effect on sperm motility parameters. Limitations, reasons for caution The biochemical and gene expression levels of KISS1 were consistent. However, gene expression was explored at the mRNA level for CATSPER1 and AKAP4. The protein expression analyses of these genes may confirm the results. Also, using kisspeptin antagonists may strength the results of intracellular calcium analysis. Wider implications of the findings Kisspeptin treatment for individuals diagnosed with asthenozoospermia may have therapeutic results. KISS1 quantitation may be a determining factor for the subfertility in routine semen analysis. Trial registration number OMU KAEK 2019/462

Oxygen increases ductus arteriosus smooth muscle cytosolic calcium via release of calcium from inositol triphosphate-sensitive stores

2005 ◽  
Vol 288 (5) ◽  
pp. L917-L923 ◽  
Author(s):  
Maggie Keck ◽  
Ernesto Resnik ◽  
Bradley Linden ◽  
Franklin Anderson ◽  
David J. Sukovich ◽  
...  
Keyword(s):  
Intracellular Calcium ◽  
Oxygen Tension ◽  
Ductus Arteriosus ◽  
Cytosolic Calcium ◽  
Extracellular Calcium ◽  
Inositol Triphosphate ◽  
Calcium Stores ◽  
Low Oxygen ◽  
Low Oxygen Tension ◽  
Pharmacological Blockade

In utero, blood shunts away from the lungs via the ductus arteriosus (DA) and the foramen ovale. After birth, the DA closes concomitant with increased oxygen tension. The present experimental series tests the hypothesis that oxygen directly increases DA smooth muscle cell (SMC) cytosolic calcium ([Ca2+]i) through inactivation of a K+ channel, membrane depolarization, and entry of extracellular calcium. To test the hypothesis, DA SMC were isolated from late-gestation fetal lambs and grown to subconfluence in primary culture in low oxygen tension (25 Torr). DA SMC were loaded with the calcium-sensitive fluorophore fura-2 under low oxygen tension conditions and studied using microfluorimetry while oxygen tension was acutely increased (120 Torr). An acute increase in oxygen tension progressively increased DA SMC [Ca2+]i by 11.7 ± 1.4% over 40 min. The effect of acute normoxia on DA SMC [Ca2+]i was mimicked by pharmacological blockade of the voltage-sensitive K+ channel. Neither removal of extracellular calcium nor voltage-operated calcium channel blockade prevented the initial increase in DA SMC [Ca2+]i. Manganese quenching experiments demonstrated that acute normoxia initially decreases the rate of extracellular calcium entry. Pharmacological blockade of inositol triphosphate-sensitive, but not ryanodine-sensitive, intracellular calcium stores prevented the oxygen-induced increase in [Ca2+]i. Endothelin increased [Ca2+]i in acutely normoxic, but not hypoxic, DA SMC. Thus acute normoxia 1) increases DA SMC [Ca2+]i via release of calcium from intracellular calcium stores, and subsequent entry of extracellular calcium, and 2) potentiates the effect of contractile agonists. Prolonged patency of the DA may result from disordered intracellular calcium homeostasis.

scholarly journals P2Y2 purinergic receptor activation is essential for efficient hepatocyte proliferation in response to partial hepatectomy

2014 ◽  
Vol 307 (11) ◽  
pp. G1073-G1087 ◽  
Author(s):  
Bryan C. Tackett ◽  
Hongdan Sun ◽  
Yu Mei ◽  
Janielle P. Maynard ◽  
Sayuri Cheruvu ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Partial Hepatectomy ◽  
Cell Cycle Progression ◽  
Purinergic Receptors ◽  
Purinergic Receptor ◽  
Receptor Activation ◽  
Hepatocyte Proliferation ◽  
Receptor Subtypes ◽  
Cycle Progression ◽  
The Impact

Extracellular nucleotides via activation of P2 purinergic receptors influence hepatocyte proliferation and liver regeneration in response to 70% partial hepatectomy (PH). Adult hepatocytes express multiple P2Y (G protein-coupled) and P2X (ligand-gated ion channels) purinergic receptor subtypes. However, the identity of key receptor subtype(s) important for efficient hepatocyte proliferation in regenerating livers remains unknown. To evaluate the impact of P2Y2 purinergic receptor-mediated signaling on hepatocyte proliferation in regenerating livers, wild-type (WT) and P2Y2 purinergic receptor knockout (P2Y2−/−) mice were subjected to 70% PH. Liver tissues were analyzed for activation of early events critical for hepatocyte priming and subsequent cell cycle progression. Our findings suggest that early activation of p42/44 ERK MAPK (5 min), early growth response-1 (Egr-1) and activator protein-1 (AP-1) DNA-binding activity (30 min), and subsequent hepatocyte proliferation (24–72 h) in response to 70% PH were impaired in P2Y2−/− mice. Interestingly, early induction of cytokines (TNF-α, IL-6) and cytokine-mediated signaling (NF-κB, STAT-3) were intact in P2Y2−/− remnant livers, uncovering the importance of cytokine-independent and nucleotide-dependent early priming events critical for subsequent hepatocyte proliferation in regenerating livers. Hepatocytes isolated from the WT and P2Y2−/− mice were treated with ATP or ATPγS for 5–120 min and 12–24 h. Extracellular ATP alone, via activation of P2Y2 purinergic receptors, was sufficient to induce ERK phosphorylation, Egr-1 protein expression, and key cyclins and cell cycle progression of hepatocytes in vitro. Collectively, these findings highlight the functional significance of P2Y2 purinergic receptor activation for efficient hepatocyte priming and proliferation in response to PH.

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