scholarly journals Collateral Vessels Have Unique Endothelial and Smooth Muscle Cell Phenotypes

2019 ◽  
Vol 20 (15) ◽  
pp. 3608 ◽  
Author(s):  
Hua Zhang ◽  
Dan Chalothorn ◽  
James E Faber
Keyword(s):  
Shear Stress ◽  
Smooth Muscle ◽  
Primary Cilia ◽  
Wall Stress ◽  
Continuous Exposure ◽  
Collateral Vessels ◽  
Oscillatory Shear Stress ◽  
Cell Phenotypes ◽  
Alternate Routes ◽  
Vessel Axis

Collaterals are unique blood vessels present in the microcirculation of most tissues that, by cross-connecting a small fraction of the outer branches of adjacent arterial trees, provide alternate routes of perfusion. However, collaterals are especially susceptible to rarefaction caused by aging, other vascular risk factors, and mouse models of Alzheimer’s disease—a vulnerability attributed to the disturbed hemodynamic environment in the watershed regions where they reside. We examined the hypothesis that endothelial and smooth muscle cells (ECs and SMCs, respectively) of collaterals have specializations, distinct from those of similarly-sized nearby distal-most arterioles (DMAs) that maintain collateral integrity despite their continuous exposure to low and oscillatory/disturbed shear stress, high wall stress, and low blood oxygen. Examination of mouse brain revealed the following: Unlike the pro-inflammatory cobble-stoned morphology of ECs exposed to low/oscillatory shear stress elsewhere in the vasculature, collateral ECs are aligned with the vessel axis. Primary cilia, which sense shear stress, are present, unexpectedly, on ECs of collaterals and DMAs but are less abundant on collaterals. Unlike DMAs, collaterals are continuously invested with SMCs, have increased expression of Pycard, Ki67, Pdgfb, Angpt2, Dll4, Ephrinb2, and eNOS, and maintain expression of Klf2/4. Collaterals lack tortuosity when first formed during development, but tortuosity becomes evident within days after birth, progresses through middle age, and then declines—results consistent with the concept that collateral wall cells have a higher turnover rate than DMAs that favors proliferative senescence and collateral rarefaction. In conclusion, endothelial and SMCs of collaterals have morphologic and functional differences from those of nearby similarly sized arterioles. Future studies are required to determine if they represent specializations that counterbalance the disturbed hemodynamic, pro-inflammatory, and pro-proliferative environment in which collaterals reside and thus mitigate their risk factor-induced rarefaction.

scholarly journals Influence of TGF-β1 expression in endothelial cells on smooth muscle cell phenotypes and MMP production under shear stress in a co-culture model

2019 ◽  
Vol 71 (2) ◽  
pp. 489-496 ◽  
Author(s):  
Xiaobo Han ◽  
Naoya Sakamoto ◽  
Noriko Tomita ◽  
Hui Meng ◽  
Masaaki Sato ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Shear Stress ◽  
Smooth Muscle ◽  
Smooth Muscle Cell ◽  
Muscle Cell ◽  
Culture Model ◽  
Cell Phenotypes ◽  
Tgf Β1

scholarly journals The Role of P53 in Transdifferentiation of EPCs into Smooth Muscle Cells Induced by Oscillatory Shear Stress

2019 ◽  
Vol 16 (s1) ◽  
pp. 93-93
Author(s):  
Yu Gao ◽  
Meiyue Wang ◽  
Yanting He ◽  
Lanlan Li ◽  
Xiaodong Cui ◽  
...  
Keyword(s):  
Shear Stress ◽  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Muscle Cells ◽  
Oscillatory Shear ◽  
Oscillatory Shear Stress

Abstract 561: Dysregulation of miR-155 in Acute Oscillatory Shear Stress (OSS)-mediated Oxidative Stress, Inflammation and Endothelial Dysfunction

2016 ◽  
Vol 36 (suppl_1) ◽  
Author(s):  
Islam Mohamed ◽  
Sheena Thomas ◽  
Kimberly Rooney ◽  
Roy Sutliff ◽  
Nick Willett ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Shear Stress ◽  
Barrier Function ◽  
Oscillatory Shear ◽  
Blue Dye ◽  
Down Regulation ◽  
Inflammatory Stress ◽  
Cytoskeleton Organization ◽  
Oscillatory Shear Stress

Introduction: Shear stress forces play an integral role in dictating the endothelial cell (EC) response to changes in blood flow, pro-inflammatory response and hence development of atherosclerosis. Previously, our group has identified EC microRNA-155 (miR-155) as one of the key signature dysregulated miRNAs in areas of chronic low magnitude oscillatory shear stress (OSS) in vasculature and OSS models of in-vitro. Hypothesis: we hypothesized that acute induction of OSS mediates EC oxidative stress, inflammation and dysfunction, via dysregulation of EC miR-155. Methods: 12-week old C57B/6J mice were subjected to abdominal aortic coarctation (AAC), a unique model of acute induction of OSS, for 3 days and downstream segments of acute OSS were compared to upstream unidirectional shear stress (USS) segments of the thoracic aorta. Results: Acute OSS resulted in down regulation of EC miR-155 expression and inverse upregulation of EC RhoA and Myosin light chain kinase (MYLK), known targets of miR-155-mediated EC cytoskeleton organization, in OSS segments compared with USS. This was associated with impaired EC dependent relaxation, differential contractile response to phenylephrine, and loss of EC barrier function as evaluated by extravasation of Evans-blue dye assay. In parallel, En-face immunohistochemical staining also showed increased expression of EC nitric oxide synthase (eNOS) along with increased levels of reactive oxygen species (ROS) and nitrotyrosine (NY) formation in OSS segments compared with USS. Conclusions: Together, our studies shed light on the early changes in EC response to acute induction of OSS and resulting down-regulation of EC mir-155, including; oxidative/inflammatory stress, EC dysfunction, loss of barrier function and cytoskeletal changes. Despite the early upregulation of eNOS, it could also potentially synergize with the activation of the RhoA-MYLK pathway in EC oxidative (ROS/NY)/inflammatory stress and associated EC dysfunction. Further studies are in progress to dissect the interplay between these different pathways and their causal relationships as downstream targets of EC miR-155.

Length-tension relationship of vascular smooth muscle in single arterioles

1989 ◽  
Vol 256 (3) ◽  
pp. H630-H640 ◽  
Author(s):  
M. J. Davis ◽  
R. W. Gore
Keyword(s):  
Smooth Muscle ◽  
Vascular Smooth Muscle ◽  
Wall Stress ◽  
Physiological Saline ◽  
Intraluminal Pressure ◽  
Cheek Pouch ◽  
Hamster Cheek Pouch ◽  
Longitudinal Response ◽  
Physiological Saline Solution ◽  
Relationship Of

Longitudinal response gradients in the microcirculation may in part be explained in terms of the length-tension relationship of vascular smooth muscle at different points along the vascular tree. To test this hypothesis, four branching orders of arterial vessels (20-80 microns ID) were dissected from the hamster cheek pouch and cannulated with concentric micropipettes. Intraluminal pressure was monitored with a servo-null micropipette, and arteriolar dimensions were measured using a videomicrometer. All arterioles developed spontaneous tone in physiological saline solution. Pressure-diameter curves were recorded for maximally activated vessels and for passive vessels. Maximal active wall tension varied nearly threefold, but maximal active medial wall stress (approximately 4 x 10(6) dyn/cm2) varied only approximately 20% between the different vessel orders. These data support the concept that smooth muscle cells from vessels of different sizes are mechanically similar but do not completely explain the longitudinal response gradients reported in the cheek pouch microcirculation. An analysis of the effect of arteriolar wall buckling suggests that the luminal folds that develop at short vessel radii may broaden the peak of the active stress-length curve and extend the pressure range over which arterioles are most sensitive to physical and chemical stimuli.

Vascular smooth muscle cell stress as a determinant of cerebral artery myogenic tone

2002 ◽  
Vol 283 (6) ◽  
pp. H2210-H2216 ◽  
Author(s):  
Johan Fredrik Brekke ◽  
Natalia I. Gokina ◽  
George Osol
Keyword(s):  
Smooth Muscle ◽  
Vascular Smooth Muscle ◽  
Smooth Muscle Cell ◽  
Muscle Cell ◽  
Vascular Smooth Muscle Cell ◽  
Wall Stress ◽  
Cytosolic Calcium ◽  
Cell Stress ◽  
Myogenic Tone ◽  
Vessel Size

Although the level of myogenic tone (MT) varies considerably from vessel to vessel, the regulatory mechanisms through which the actual diameter set point is determined are not known. We hypothesized that a unifying principle may be the equalization of active force at the contractile filament level, which would be reflected in a normalization of wall stress or, more specifically, media stress. Branched segments of rat cerebral arteries ranging from <50 μm to >200 μm in diameter were cannulated and held at 60 mmHg with the objectives of: 1) evaluating the relationship between arterial diameter and the extent of myogenic tone, 2) determining whether differences in MT correlate with changes in cytosolic calcium ([Ca2+]i), and 3) testing the hypothesis that a normalization of wall or media stress occurs during the process of tone development. The level of MT increased significantly as vessel size decreased. At 60 mmHg, vascular smooth muscle [Ca2+]i concentrations were similar in all vessels studied (averaging 230 ± 9.2 nM) and not correlated with vessel size or the extent of tone. Wall tension increased with increasing arterial size, but wall stress and media stress were similar in large versus small arteries. Media stress, in particular, was quite uniform in all vessels studied. Both morphological and calcium data support the concept of equalization of media stress (and, hence, vascular smooth muscle cell stress and force) as an underlying mechanism in determining the level of tone present in any particular vessel. The equalization of active (vascular smooth muscle cell) stress may thus explain differences in MT observed in the different-sized vessels constituting the arterial network and provide a link between arterial structure and function, in both short- and long-term (hypertension) pressure adaptation.

scholarly journals Lysophosphatidyl choline modulates mechanosensitive L-type Ca2+ current in circular smooth muscle cells from human jejunum

2009 ◽  
Vol 296 (4) ◽  
pp. G833-G839 ◽  
Author(s):  
Robert E. Kraichely ◽  
Peter R. Strege ◽  
Michael G. Sarr ◽  
Michael L. Kendrick ◽  
Gianrico Farrugia
Keyword(s):  
Shear Stress ◽  
Smooth Muscle ◽  
Lipid Bilayer ◽  
Stress Perfusion ◽  
Inactivation Kinetics ◽  
Circular Smooth Muscle ◽  
Lysophosphatidyl Choline ◽  
Membrane Stretch ◽  
Circular Layer ◽  
Patch Configuration

The L-type Ca2+ channel expressed in gastrointestinal smooth muscle is mechanosensitive. Direct membrane stretch and shear stress result in increased Ca2+ entry into the cell. The mechanism for mechanosensitivity is not known, and mechanosensitivity is not dependent on an intact cytoskeleton. The aim of this study was to determine whether L-type Ca2+ channel mechanosensitivity is dependent on tension in the lipid bilayer in human jejunal circular layer myocytes. Whole cell currents were recorded in the amphotericin-perforated-patch configuration, and lysophosphatidyl choline (LPC), lysophosphatidic acid (LPA), and choline were used to alter differentially the tension in the lipid bilayer. Shear stress (perfusion at 10 ml/min) was used to mechanostimulate L-type Ca2+ channels. The increase in L-type Ca2+ current induced by shear stress was greater in the presence of LPC (large head-to-tail proportions), but not LPA or choline, than in the control perfusion. The increased peak Ca2+ current also did not return to baseline levels as in control conditions. Furthermore, steady-state inactivation kinetics were altered in the presence of LPC, leading to a change in window current. These findings suggest that changes in tension in the plasmalemmal membrane can be transmitted to the mechanosensitive L-type Ca2+ channel, leading to altered activity and Ca2+ entry in the human jejunal circular layer myocyte.

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