Endothelial cell calcium increases during flow-induced dilation in isolated arterioles

1993 ◽  
Vol 264 (2) ◽  
pp. H653-H659 ◽  
Author(s):  
J. C. Falcone ◽  
L. Kuo ◽  
G. A. Meininger
Keyword(s):  
Endothelial Cells ◽  
Endothelial Cell ◽  
Endothelial Function ◽  
Intracellular Calcium ◽  
Digital Image ◽  
Calcium Concentration ◽  
Strong Support ◽  
Fluorescence Microscope ◽  
Fura 2 ◽  
Flow Through

The influence of flow on endothelial intracellular calcium concentration ([Ca2+]i) was determined in intact, isolated arterioles by selectively loading endothelial cells with the calcium-sensitive fluorescent dye fura-2. A fluorescence microscope coupled to a digital image processor was used to simultaneously measure fura-2 fluorescence and microvessel diameter. Flow through the arteriole significantly increased endothelial [Ca2+]i and dilated arterioles. Acetylcholine also increased in endothelial [Ca2+]i and caused vasodilation. In comparison, adenosine did not alter endothelial [Ca2+]i but dilated arterioles. Removal of the endothelium abolished the responses to flow and acetylcholine but not adenosine. These results provide strong support for the involvement of calcium in endothelium-dependent dilation of isolated arterioles by flow and agonists and emphasize the importance of studying endothelial function in intact vessels.

scholarly journals Sickle erythrocytes inhibit human endothelial cell DNA synthesis

Blood ◽  
1990 ◽  
Vol 76 (10) ◽  
pp. 2146-2152 ◽  
Author(s):  
R Weinstein ◽  
MA Zhou ◽  
A Bartlett-Pandite ◽  
K Wenc
Keyword(s):  
Endothelial Cells ◽  
Endothelial Cell ◽  
Endothelial Function ◽  
Dna Synthesis ◽  
Sickle Cell ◽  
Sickle Cell Anemia ◽  
Inhibitory Effect ◽  
Human Endothelial Cell ◽  
Endothelial Monolayers ◽  
Sickle Erythrocytes

Abstract Patients with sickle cell anemia experience severe vascular occlusive phenomena including acute pain crisis and cerebral infarction. Obstruction occurs at both the microvascular and the arterial level, and the clinical presentation of vascular events is heterogeneous, suggesting a complex etiology. Interaction between sickle erythrocytes and the endothelium may contribute to vascular occlusion due to alteration of endothelial function. To investigate this hypothesis, human vascular endothelial cells were overlaid with sickle or normal erythrocytes and stimulated to synthesize DNA. The erythrocytes were sedimented onto replicate monolayers by centrifugation for 10 minutes at 17 g to insure contact with the endothelial cells. Incorporation of 3H-thymidine into endothelial cell DNA was markedly inhibited during contact with sickle erythrocytes. This inhibitory effect was enhanced more than twofold when autologous sickle plasma was present during endothelial cell labeling. Normal erythrocytes, with or without autologous plasma, had a modest effect on endothelial cell DNA synthesis. When sickle erythrocytes in autologous sickle plasma were applied to endothelial monolayers for 1 minute, 10 minutes, or 1 hour and then removed, subsequent DNA synthesis by the endothelial cells was inhibited by 30% to 40%. Although adherence of sickle erythrocytes to the endothelial monolayers was observed under these experimental conditions, the effect of sickle erythrocytes on endothelial DNA synthesis occurred in the absence of significant adherence. Hence, human endothelial cell DNA synthesis is partially inhibited by contact with sickle erythrocytes. The inhibitory effect of sickle erythrocytes occurs during a brief (1 minute) contact with the endothelial monolayers, and persists for at least 6 hours of 3H-thymidine labeling. These results indicate that interaction between sickle erythrocytes and the endothelium may result in altered endothelial function. This altered endothelial function may contribute to the development of vascular occlusive phenomena in patients with sickle cell anemia.

Axotomy induces a transient and localized elevation of the free intracellular calcium concentration to the millimolar range

1995 ◽  
Vol 74 (6) ◽  
pp. 2625-2637 ◽  
Author(s):  
N. E. Ziv ◽  
M. E. Spira
Keyword(s):  
Intracellular Calcium ◽  
Calcium Concentration ◽  
Intracellular Calcium Concentration ◽  
Concentration Gradients ◽  
Fura 2 ◽  
Direct Demonstration ◽  
Free Intracellular Calcium ◽  
Axonal Transection ◽  
Transient Elevation

1. Axonal transection triggers a cascade of pathological processes that frequently lead to the degeneration of the injured neuron. It is generally believed that the degenerative process is triggered by an overwhelming influx of calcium through the cut end of the axon. 2. Theoretical considerations and indirect observations suggest that axotomy is followed by an increase in the free intracellular calcium concentration ([Ca2+]i) to the millimolar level. In contrast, only relatively modest and transient elevation in [Ca2+]i to the micromolar level was revealed by recent fura-2 studies. 3. In the current study we used the low-affinity Ca2+ indicator mag-fura-2 to reexamine the spatiotemporal distribution pattern of Ca2+ after axotomy and to map the free intracellular Mg2+ concentration gradients. 4. We report that axotomy elevates [Ca2+]i well beyond the "physiological" range of calcium concentrations, to levels > 1 mM near the tip of the cut axon and to hundreds of micromolars along the axon further away from the cut end. Nevertheless, [Ca2+]i recovers to the control levels within 2-3 min after the resealing of the cut end. 5. A comparison of the behavior of fura-2 and mag-fura-2 in the cytosol of the axotomized neurons reveals that the determination of [Ca2+]i by fura-2 largely underestimates the actual intracellular Ca2+ concentrations. 6. Experiments in which one branch of a bifurcated axon was transected revealed that the elevation in [Ca2+]i is confined to the transected axonal branch and does not spread beyond the bifurcation point. 7. After axotomy, the intracellular Mg2+ concentration equilibrates rapidly with the external concentration and then recovers at a rate somewhat slower than that of [Ca2+]i. 8. To the best of our knowledge, this study is the first direct demonstration that axotomy elevates [Ca2+]i to the millimolar range and that neurons are able to recover from these extreme calcium concentrations.

Hypotonic stress-induced dual Ca2+ responses in bovine aortic endothelial cells

2000 ◽  
Vol 279 (2) ◽  
pp. H630-H638 ◽  
Author(s):  
Masahiro Oike ◽  
Chiwaka Kimura ◽  
Tetsuya Koyama ◽  
Miyuki Yoshikawa ◽  
Yushi Ito
Keyword(s):  
Endothelial Cells ◽  
Arachidonic Acid ◽  
Receptor Antagonist ◽  
Intracellular Calcium ◽  
Calcium Concentration ◽  
Luciferase Assay ◽  
Aortic Endothelial Cells ◽  
Hypotonic Stress ◽  
Bovine Aortic Endothelial Cells ◽  
Aortic Endothelial

We have investigated the effects of hypotonic stress on intracellular calcium concentration ([Ca2+]i) in bovine aortic endothelial cells. Reducing extracellular osmolarity by 5% to 40% elicited a steep Ca2+ transient both in normal Krebs and Ca2+-free solutions. The hypotonic stress-induced Ca2+ transient was inhibited by phospholipase C inhibitors (neomycin and U-73122), a P2-receptor antagonist (suramin), and an ATP-hydrolyzing enzyme (apyrase), suggesting that the hypotonic stress-induced Ca2+ transient is mediated by ATP. A luciferin-luciferase assay confirmed that 40% hypotonic stress released 91.0 amol/cell of ATP in 10 min. When the hypotonic stress-induced fast Ca2+ transient was inhibited by neomycin, suramin, or apyrase, a gradual [Ca2+]i increase was observed instead. This hypotonic stress-induced gradual [Ca2+]iincrease was inhibited by a phospholipase A2 inhibitor, 4-bromophenacyl bromide. Furthermore, exogenously applied arachidonic acid induced a gradual [Ca2+]i increase with an ED50 of 13.3 μM. These observations indicate that hypotonic stress induces a dual Ca2+ response in bovine aortic endothelial cells, i.e., an ATP-mediated fast Ca2+transient and an arachidonic acid-mediated gradual Ca2+increase, the former being the predominant response in normal conditions.

Effect of hypoxia upon intracellular calcium concentration of human endothelial cells

1992 ◽  
Vol 152 (1) ◽  
pp. 215-221 ◽  
Author(s):  
Thierry Arnould ◽  
Carine Michiels ◽  
Isabelle Alexandre ◽  
Jos� Remacle
Keyword(s):  
Endothelial Cells ◽  
Intracellular Calcium ◽  
Calcium Concentration ◽  
Intracellular Calcium Concentration ◽  
Human Endothelial Cells

Albumin modulation of capillary permeability: role of endothelial cell [Ca2+]i

1993 ◽  
Vol 265 (1) ◽  
pp. H74-H82 ◽  
Author(s):  
P. He ◽  
F. E. Curry
Keyword(s):  
Endothelial Cells ◽  
Endothelial Cell ◽  
Calcium Concentration ◽  
Capillary Permeability ◽  
Common Mechanism ◽  
Cytoplasmic Calcium ◽  
Adsorption Model ◽  
Endothelial Cell Surface ◽  
Mesenteric Microvessels

Albumin is required in vascular perfusates to maintain the normal permeability of microvessel walls. The most common mechanism proposed for action of albumin involves binding to the endothelial cell surface to increase the resistance to water and solute flows through hydraulic pathways across the capillary wall. The results of the present experiments do not conform to this simple adsorption model. Ringer perfusion increased the hydraulic conductivity (Lp) of the wall of single perfused frog mesenteric microvessels by 4.0 +/- 0.5-fold. The increase in Lp was associated with an increase of cytoplasmic calcium concentration ([Ca2+]i) from 59 +/- 5 nM when albumin was in the perfusate to a transient peak of 181 +/- 13 nM, 1–2 min after Ringer perfusion. [Ca2+]i then fell back to close to 100 nM. Processes that reduced Ca2+ influx into endothelial cells (removal of extracellular Ca2+, membrane depolarization) reduced Ca2+ influx and attenuated the increase in [Ca2+]i. The same processes abolished the increase in Lp after Ringer perfusion and restored Lp to close to control values during Ringer perfusion. Thus Ca2+ entry into endothelial cells is required to initiate and maintain the increased permeability during Ringer perfusion.

Heterogeneous response of microvascular endothelial cells to shear stress

2006 ◽  
Vol 290 (6) ◽  
pp. H2498-H2508 ◽  
Author(s):  
D. Hong ◽  
D. Jaron ◽  
D. G. Buerk ◽  
K. A. Barbee
Keyword(s):  
Endothelial Cells ◽  
Shear Stress ◽  
Intracellular Calcium ◽  
Purinergic Receptors ◽  
Calcium Concentration ◽  
Intracellular Calcium Concentration ◽  
Calcium Signal ◽  
Calcium Waves ◽  
Aortic Endothelial Cells ◽  
Atp Concentration

We investigated changes in calcium concentration in cultured bovine aortic endothelial cells (BAECs) and rat adrenomedulary endothelial cells (RAMECs, microvascular) in response to different levels of shear stress. In BAECs, the onset of shear stress elicited a transient increase in intracellular calcium concentration that was spatially uniform, synchronous, and dose dependent. In contrast, the response of RAMECs was heterogeneous in time and space. Shear stress induced calcium waves that originated from one or several cells and propagated to neighboring cells. The number and size of the responding groups of cells did not depend on the magnitude of shear stress or the magnitude of the calcium change in the responding cells. The initiation and the propagation of calcium waves in RAMECs were significantly suppressed under conditions in which either purinergic receptors were blocked by suramin or extracellular ATP was degraded by apyrase. Exogenously applied ATP produced similarly heterogeneous responses. The number of responding cells was dependent on ATP concentration, but the magnitude of the calcium change was not. Our data suggest that shear stress stimulates RAMECs to release ATP, causing the increase in intracellular calcium concentration via purinergic receptors in cells that are heterogeneously sensitive to ATP. The propagation of the calcium signal is also mediated by ATP, and the spatial pattern suggests a locally elevated ATP concentration in the vicinity of the initially responding cells.

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