Shear stress and 17β-estradiol modulate cerebral microvascular endothelial Na-K-Cl cotransporter and Na/H exchanger protein levels

2008 ◽  
Vol 294 (1) ◽  
pp. C363-C371 ◽  
Author(s):  
Elaine Chang ◽  
Martha E. O'Donnell ◽  
Abdul I. Barakat
Keyword(s):  
Endothelial Cells ◽  
Blood Flow ◽  
Shear Stress ◽  
Ischemic Stroke ◽  
Edema Formation ◽  
Protein Levels ◽  
Prominent Component ◽  
17Β Estradiol ◽  
Microvascular Endothelial ◽  
Brain Edema Formation

Ion transporters of blood-brain barrier (BBB) endothelial cells play an important role in regulating the movement of ions between the blood and brain. During ischemic stroke, reduction in cerebral blood flow is accompanied by transport of Na and Cl from the blood into the brain, with consequent brain edema formation. We have shown previously that a BBB Na-K-Cl cotransporter (NKCC) participates in ischemia-induced brain Na and water uptake and that a BBB Na/H exchanger (NHE) may also participate. While the abrupt reduction of blood flow is a prominent component of ischemia, the effects of flow on BBB NKCC and NHE are not known. In the present study, we examined the effects of changes in shear stress on NKCC and NHE protein levels in cerebral microvascular endothelial cells (CMECs). We have shown previously that estradiol attenuates both ischemia-induced cerebral edema and CMEC NKCC activity. Thus, in the present study, we also examined the effects of estradiol on NKCC and NHE protein levels in CMECs. Exposing CMECs to steady shear stress (19 dyn/cm2) increased the abundance of both NKCC and NHE. Estradiol abolished the shear stress-induced increase in NHE but not NKCC. Abrupt reduction of shear stress did not alter NKCC or NHE abundance in the absence of estradiol, but it decreased NKCC abundance in estradiol-treated cells. Our results indicate that changes in shear stress modulate BBB NKCC and NHE protein levels. They also support the hypothesis that estradiol attenuates edema formation in ischemic stroke in part by reducing the abundance of BBB NKCC protein.

scholarly journals Ischemia-induced stimulation of Na-K-Cl cotransport in cerebral microvascular endothelial cells involves AMP kinase

2011 ◽  
Vol 301 (2) ◽  
pp. C316-C326 ◽  
Author(s):  
Breanna K. Wallace ◽  
Shahin Foroutan ◽  
Martha E. O'Donnell
Keyword(s):  
Endothelial Cells ◽  
Ischemic Stroke ◽  
Brain Slices ◽  
Glucose Deprivation ◽  
Artery Occlusion ◽  
Microvascular Endothelial Cells ◽  
Edema Formation ◽  
Compound C ◽  
Microvascular Endothelial ◽  
Stimulation Of

Increased blood-brain barrier (BBB) Na-K-Cl cotransporter activity appears to contribute to cerebral edema formation during ischemic stroke. We have shown previously that inhibition of BBB Na-K-Cl cotransporter activity reduces edema and infarct in the rat middle cerebral artery occlusion (MCAO) model of ischemic stroke. We have also shown that the BBB cotransporter is stimulated by the ischemic factors hypoxia, aglycemia, and arginine vasopressin (AVP), although the mechanisms responsible are not well understood. AMP-activated protein kinase (AMPK), a key mediator of cell responses to stress, can be activated by a variety of stresses, including ischemia, hypoxia, and aglycemia. Previous studies have shown that the AMPK inhibitor Compound C significantly reduces infarct in mouse MCAO. The present study was conducted to evaluate the possibility that AMPK participates in ischemic factor-induced stimulation of the BBB Na-K-Cl cotransporter. Cerebral microvascular endothelial cells (CMEC) were assessed for Na-K-Cl cotransporter activity as bumetanide-sensitive86Rb influx. AMPK activity was assessed by Western blot analysis and immunofluorescence methods using antibodies that detect total versus phosphorylated (activated) AMPK. We found that hypoxia (7% and 2% O2), aglycemia, AVP, and oxygen-glucose deprivation (5- to 120-min exposures) increase activation of AMPK. We also found that Compound C inhibition of AMPK reduces hypoxia-, aglycemia-, and AVP-induced stimulation of CMEC Na-K-Cl cotransporter activity. Confocal immunofluorescence of perfusion-fixed rat brain slices revealed the presence of AMPK, both total and phosphorylated kinase, in BBB in situ of both control and ischemic brain. These findings suggest that ischemic factor stimulation of the BBB Na-K-Cl cotransporter involves activation of AMPK.

Biomechanical and biochemical regulation of cathepsin K expression in endothelial cells converge at AP-1 and NF-κB

2016 ◽  
Vol 397 (5) ◽  
pp. 459-468 ◽  
Author(s):  
Philip M. Keegan ◽  
Suhaas Anbazhakan ◽  
Baolin Kang ◽  
Betty S. Pace ◽  
Manu O. Platt
Keyword(s):  
Endothelial Cells ◽  
Blood Flow ◽  
Shear Stress ◽  
Cathepsin K ◽  
Mrna Levels ◽  
Arterial Remodeling ◽  
Aortic Endothelial Cells ◽  
Protein Levels ◽  
Biomechanical Stimuli ◽  
Factor Α

Abstract Cathepsins K and V are powerful elastases elevated in endothelial cells by tumor necrosis factor-α (TNFα) stimulation and disturbed blood flow both of which contribute to inflammation-mediated arterial remodeling. However, mechanisms behind endothelial cell integration of biochemical and biomechanical cues to regulate cathepsin production are not known. To distinguish these mechanisms, human aortic endothelial cells (HAECs) were stimulated with TNFα and exposed to pro-remodeling or vasoprotective shear stress profiles. TNFα upregulated cathepsin K via JNK/c-jun activation, but vasoprotective shear stress inhibited TNFα-stimulated cathepsin K expression. JNK/c-jun were still phosphorylated, but cathepsin K mRNA levels were significantly reduced to almost null indicating separate biomechanical regulation of cathepsin K by shear stress separate from biochemical stimulation. Treatment with Bay 11-7082, an inhibitor of IκBα phosphorylation, was sufficient to block induction of cathepsin K by both pro-remodeling shear stress and TNFα, implicating NF-κB as the biomechanical regulator, and its protein levels were reduced in HAECs by vasoprotective shear stress. In conclusion, NF-κB and AP-1 activation were necessary to activate cathepsin K expression in endothelial cells, highlighting integration of biochemical and biomechanical stimuli to control cathepsins K and V, powerful elastases implicated for arterial remodeling due to chronic inflammation and disturbed blood flow.

Stimulation of Tetrahydrobiopterin Synthesis by 17β-Estradiol in Brain Microvascular Endothelial Cells

Pteridines ◽  
2000 ◽  
Vol 11 (4) ◽  
pp. 129-132
Author(s):  
Kazuhiro Shiota ◽  
Masakazu Ishii ◽  
Toshinori Yamamoto ◽  
Shunichi Shimizu ◽  
Yuji Kiuchi
Keyword(s):  
Endothelial Cells ◽  
De Novo ◽  
Vascular Endothelial Cells ◽  
Mrna Level ◽  
Microvascular Endothelial Cells ◽  
No Production ◽  
Brain Microvascular Endothelial Cells ◽  
Protective Effects ◽  
17Β Estradiol ◽  
Microvascular Endothelial

Abstract The purpose of this study was to examine whether 17β-estradiol stimulates the synthesis of tetrahydrobiopterin : BH4), which is one of the cofactors of nitric oxide (NO) synthase, in mouse brain microvascular endothelial cells. Addition of 17()-estradiol to endothelial cells time- and concentration-dependently increased intracellular BH4 level. 17β-Estradiol also stimulated the mRNA level of GTP-cyclohydrolase I (GTPCH), which is a rate-limiting enzyme of the de novo BH4 synthetic pathway. In addition, the 17β-estradiol-induced expression of GTPCH mRNA was strongly attenuated by treatment with an inhibitor of 17β-estradiol receptor 4-hydroxy-tamoxlfen. These results suggest that 17β-estradiol stimulates BH4 synthesis through the induction of GTPCH by tamoxifensensitive receptor in vascular endothelial cells. The 17β-estradiol-induced increase in BH4 level might be implicated in not only NO production, but also protective effects of 17β-estradiol against ischemic brain damage and atherosclerosis, since BH4 is an intracellular antioxidant.

Shear stress increases expression of a KATP channel in rat and bovine pulmonary vascular endothelial cells

2003 ◽  
Vol 285 (4) ◽  
pp. C959-C967 ◽  
Author(s):  
Shampa Chatterjee ◽  
Abu-Bakr Al-Mehdi ◽  
Irena Levitan ◽  
Troy Stevens ◽  
Aron B. Fisher
Keyword(s):  
Endothelial Cells ◽  
Shear Stress ◽  
Membrane Depolarization ◽  
Microvascular Endothelial Cells ◽  
Adaptation Period ◽  
Pulmonary Microvascular Endothelial Cells ◽  
Channel Expression ◽  
Microvascular Endothelial ◽  
Flow Adaptation ◽  
Expression And Activity

We have shown previously that acute ischemia leads to depolarization of pulmonary microvascular endothelial cells that is prevented with cromakalim, suggesting the presence of ATP-sensitive K+ (KATP) channels in these cells. Thus KATP channel expression and activity were evaluated in rat pulmonary microvascular endothelial cells (RPMVEC) by whole cell current measurements, dot blot (mRNA), and immunoblot (protein) for the inwardly rectifying K+ channel (KIR) 6.2 subunit and fluorescent ligand binding for the sulfonylurea receptor (SUR). Low-level expression of a KATP channel was detected in endothelial cells in routine (static) culture and led us to examine whether its expression is inducible when endothelial cells are adapted to flow. Channel expression (mRNA and both KIR6.2 and SUR proteins) and inwardly rectified membrane current by patch clamp increased significantly when RPMVEC were adapted to flow at 10 dyn/cm2 for 24 h in either a parallel plate flow chamber or an artificial capillary system. Induction of the KATP channel with flow adaptation was also observed in bovine pulmonary artery endothelial cells. Flow-adapted but not static RPMVEC showed cellular plasma membrane depolarization upon stop of flow that was inhibited by a KATP channel opener and prevented by addition of cycloheximide to the medium during the flow adaptation period. These studies indicate the induction of KATP channels by flow adaptation in pulmonary endothelium and that the expression and activity of this channel are essential for the endothelial cell membrane depolarization response with acute decrease in shear stress.

scholarly journals Human brain microvascular endothelial cells resist elongation due to shear stress

2015 ◽  
Vol 99 ◽  
pp. 8-18 ◽  
Author(s):  
Adam Reinitz ◽  
Jackson DeStefano ◽  
Mao Ye ◽  
Andrew D. Wong ◽  
Peter C. Searson
Keyword(s):  
Endothelial Cells ◽  
Shear Stress ◽  
Human Brain ◽  
Microvascular Endothelial Cells ◽  
Brain Microvascular Endothelial Cells ◽  
Microvascular Endothelial

Microvascular dilation in response to occlusion: a coordinating role for conducted vasomotor responses

2000 ◽  
Vol 279 (1) ◽  
pp. H279-H284 ◽  
Author(s):  
Kim A. Dora ◽  
David N. Damon ◽  
Brian R. Duling
Keyword(s):  
Endothelial Cells ◽  
Blood Flow ◽  
Shear Stress ◽  
Smooth Muscle ◽  
Third Order ◽  
Vasomotor Responses ◽  
Vasodilatory Response ◽  
Flow Through ◽  
Stress Dependent ◽  
Dependent Mechanism

In rat cremasteric microcirculation, mechanical occlusion of one branch of an arteriolar bifurcation causes an increase in flow and vasodilation of the unoccluded daughter branch. This dilation has been attributed to the operation of a shear stress-dependent mechanism in the microcirculation. Instead of or in addition to this, we hypothesized that the dilation observed during occlusion is the result of a conducted signal originating distal to the occlusion. To test this hypothesis, we blocked the ascending spread of conducted vasomotor responses by damaging the smooth muscle and endothelial cells in a 200-μm segment of second- or third-order arterioles. We found that a conduction blockade eliminated or diminished the occlusion-associated increase in flow through the unoccluded branch and abolished or strongly attenuated the vasodilatory response in both vessels at the branch. We also noted that vasodilations induced by ACh (10−4 M, 0.6 s) spread to, but not beyond, the area of damage. Taken together, these data provide strong evidence that conducted vasomotor responses have an important role in coordinating blood flow in response to an arteriolar occlusion.

Flow Induced Vasodilation in Porcine Carotid Arteries

2012 ◽  
Author(s):  
Renate W. Boekhoven ◽  
Tatjana Maas ◽  
Marcel C. M. Rutten ◽  
Frans N. van de Vosse
Keyword(s):  
Endothelial Cells ◽  
Blood Flow ◽  
Shear Stress ◽  
Carotid Arteries ◽  
Physiological Flow ◽  
Vasoactive Substances ◽  
Cardiovascular Pathologies

Endothelial cells play an important role in the autoregulation of the vascular diameter for maintaining physiological flow and shear stress. An increase in blood flow causes an increase in shear stress, which is sensed by the endothelial cells, resulting in the release of vasoactive substances. An impaired endothelial mediated vasomotive response seems reflective for several cardiovascular pathologies, such as failure of atherosclerosis and arterio-venous fistulas (AVF).

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