Microarray profiling revealsCXCR4ais downregulated by blood flow in vivo and mediates collateral formation in zebrafish embryos

The response to hemodynamic force is implicated in a number of pathologies including collateral vessel development. However, the transcriptional effect of hemodynamic force is extremely challenging to examine in vivo in mammals without also detecting confounding processes such as hypoxia and ischemia. We therefore serially examined the transcriptional effect of preventing cardiac contraction in zebrafish embryos which can be deprived of circulation without experiencing hypoxia since they obtain sufficient oxygenation by diffusion. Morpholino antisense knock-down of cardiac troponin T2 ( tnnt2) prevented cardiac contraction without affecting vascular development. Gene expression in whole embryo RNA from tnnt2 or control morphants at 36, 48, and 60 h postfertilization (hpf) was assessed using Affymetrix GeneChip Zebrafish Genome Arrays (>14,900 transcripts). We identified 308 differentially expressed genes between tnnt2 and control morphants. One such ( CXCR4a) was significantly more highly expressed in tnnt2 morphants at 48 and 60 hpf than controls. In situ hybridization localized CXCR4a upregulation to endothelium of both tnnt2 morphants and gridlock mutants (which have an occluded aorta preventing distal blood flow). This upregulation appears to be of functional significance as either CXCR4a knock-down or pharmacologic inhibition impaired the ability of gridlock mutants to recover blood flow via collateral vessels. We conclude absence of hemodynamic force induces endothelial CXCR4a upregulation that promotes recovery of blood flow.

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A blood flow–dependent klf2a-NO signaling cascade is required for stabilization of hematopoietic stem cell programming in zebrafish embryos

Blood ◽

10.1182/blood-2011-05-353235 ◽

2011 ◽

Vol 118 (15) ◽

pp. 4102-4110 ◽

Cited By ~ 61

Author(s):

Lu Wang ◽

Panpan Zhang ◽

Yonglong Wei ◽

Ya Gao ◽

Roger Patient ◽

...

Keyword(s):

Blood Flow ◽

Signaling Cascade ◽

Zebrafish Embryos ◽

Hematopoietic Stem ◽

Hemodynamic Forces ◽

No Signaling ◽

Vessel Development ◽

And Function ◽

Chip Analysis

Abstract Blood flow has long been thought to be important for vessel development and function, but its role in HSC development is not yet fully understood. Here, we take advantage of zebrafish embryos with circulation defects that retain relatively normal early development to illustrate the combinatorial roles of genetic and hemodynamic forces in HSC development. We show that blood flow is not required for initiation of HSC gene expression, but instead is indispensable for its maintenance. Knockdown of klf2a mimics the silent heart (sih/tnnt2a) phenotype while overexpression of klf2a in tnnt2a morphant embryos can rescue HSC defects, suggesting that klf2a is a downstream mediator of blood flow. Furthermore, the expression of NO synthase (nos) was reduced in klf2a knockdown embryos, and ChIP analysis showed that endogenous Klf2a is bound to the promoters of nos genes in vivo, indicating direct gene regulation. Finally, administration of the NO agonist S-nitroso N-acetylpenicillamine (SNAP) can restore HSC development in tnnt2a and klf2a morphants, suggesting that NO signaling is downstream of Klf2a which is induced by hemodynamic forces. Taken together, we have demonstrated that blood flow is essential for HSC development and is mediated by a klf2a-NO signaling cascade in zebrafish.

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Inhibitory effect of cardiac contraction on coronary collateral blood flow

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.1977.233.5.h541 ◽

1977 ◽

Vol 233 (5) ◽

pp. H541-H546 ◽

Cited By ~ 3

Author(s):

R. E. Russell ◽

R. W. Chagrasulis ◽

J. M. Downey

Keyword(s):

Blood Flow ◽

Left Coronary Artery ◽

Constant Pressure ◽

Inhibitory Effect ◽

Cardiac Contraction ◽

Collateral Blood Flow ◽

Ischemic Region ◽

Perfusion Apparatus ◽

Collateral Vessels ◽

Coronary Collateral Blood Flow

The present study was undertaken to determine the effect of contraction on overall flow in an area supplied by collateral vessels. Changes in the distribution of blood flow across the wall of ischemic and normally perfused regions of the left ventricle were observed during normal beating and during vagal arrest. The main left coronary artery was cannulated and perfused at constant pressure (125 mmHg) using a servo pump apparatus. An ischemic area supplied by collaterals was created by ligating the left anterior descending artery. Radiomicrospheres (15 micrometer) were injected into the perfusion apparatus during beating. Then spheres with a different label were administered to the same heart during arrest. The results revealed that beating caused a gradient of blood flow inhibition from near zero at the epicardium to about 50% at the endocardium in both zones. Inhibition to flow at the mid wall of the ischemic zone, 71%, was significantly greater than that seen at the corresponding depth in the normally perfused region, 33%. These results indicate that contraction not only inhibits collateral blood flow to an ischemic region, but also that the inhibition is actually magnified at the mid wall.

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Cessation of contraction induces cardiomyocyte remodeling during zebrafish cardiogenesis

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.00721.2013 ◽

2014 ◽

Vol 306 (3) ◽

pp. H382-H395 ◽

Cited By ~ 6

Author(s):

Jingchun Yang ◽

Katherine A. Hartjes ◽

Timothy J. Nelson ◽

Xiaolei Xu

Keyword(s):

Signaling Pathways ◽

Heart Development ◽

Myosin Ii ◽

Cardiac Contraction ◽

Zebrafish Embryos ◽

Mechanical Forces ◽

In Vivo Animal Model ◽

Lateral Fusion ◽

Phosphoinositide 3 Kinase

Contraction regulates heart development via a complex mechanotransduction process controlled by various mechanical forces. Here, we exploit zebrafish embryos as an in vivo animal model to discern the contribution from different mechanical forces and identify the underlying mechanotransductive signaling pathways of cardiogenesis. We treated 2 days postfertilization zebrafish embryos with Blebbistatin, a myosin II inhibitor, to stop cardiac contraction, which induces a response termed cessation of contraction-induced cardiomyocyte (CM) enlargement (CCE). Accompanying the CCE, lateral fusion of myofibrils was attenuated within CMs. The CCE can be blunted by loss of blood in tail-docked zebrafish but not in cloche mutant fish, suggesting that transmural pressure rather than shear stress is accountable for the chamber enlargement. By screening a panel of small molecule inhibitors, our data suggested essential functions of phosphoinositide 3-kinase signaling and protein synthesis in CCE, which are independent of the sarcomere integrity. In summary, we defined a unique CCE response in genetically tractable zebrafish embryos. A panel of assays was established to verify the contribution from extrinsic forces and interrogate underlying signaling pathways.

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Mechanical determinants of coronary blood flow during dynamic alterations in myocardial contractility

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.1993.265.4.h1112 ◽

1993 ◽

Vol 265 (4) ◽

pp. H1112-H1118 ◽

Cited By ~ 1

Author(s):

L. J. Mulligan ◽

D. Escobedo ◽

G. L. Freeman

Keyword(s):

Blood Flow ◽

Coronary Blood Flow ◽

Average Rate ◽

Left Ventricular ◽

Cardiac Contraction ◽

Ventricular Elastance ◽

Pulsus Alternans ◽

Pressure Development ◽

Maximal Pressure ◽

And Control

Recently it has been proposed that the decrease in coronary blood flow (CBF) resulting from cardiac contraction referred to as systolic flow impediment (SFI) is dependent on the level of left ventricular elastance (Ees). The average rate of LV relaxation (Ravg) has been shown to be major determinant of diastolic flow development (DFD). We tested these hypotheses using the unique hemodynamic condition of pulsus alternans (PA) where end-systolic LV pressure and instantaneous Ees vary on beat-to-beat basis. In six mongrel dogs instrumented with LV and aortic manometers, ultrasonic dimension crystals, and Doppler coronary flow probes we measured phasic CBF and Ees during PA and control conditions. Maximal pressure development over time (dP/dtmax) and SFI were significantly different between weak (WB) and strong beats (SB) as were Ravg and DFD. Minimum CBF (Qmin) was not different between SB and WB; however, Qmin and peak Ees occurred nearly simultaneously in the WB. Qmin occurred much earlier than peak Ees in the strong and control beats. Plots of instantaneous LV elastance and CBF showed that for control beats and for the strong beats of PA CBF was similar during systole and diastole, suggesting elastance is a unique determinant of CBF. This was quantified as CBF at the time in either systole or diastole when elastance was half-maximal for that beat (E50). During the WB of PA, however, CBF at E50 was significantly higher during systole than during diastole. We conclude that while SFI and DFD are highly dependent on the dP/dt and Ravg, Ees is not a unique determinant of CBF under all conditions.

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Precise, 3-D optogenetic control of the diameter of single arterioles

10.1101/2021.01.29.428609 ◽

2021 ◽

Author(s):

Philip J. O’Herron ◽

David A. Hartmann ◽

Kun Xie ◽

Prakash Kara ◽

Andy Y. Shih

Keyword(s):

Blood Flow ◽

Neural Activity ◽

Light Modulator ◽

Spatiotemporal Resolution ◽

Two Photon ◽

Light Pulses ◽

All Optical ◽

Health And Disease ◽

And Control

AbstractModulation of brain arteriole diameter is critical for maintenance of cerebral blood pressure and control of hyperemia during regional neural activity. However, studies of hemodynamic function in health and disease have lacked a method to control and monitor blood flow with high spatiotemporal resolution. Here, we describe a new all-optical approach to precisely control and monitor arteriolar contractility in vivo using combined two-photon optogenetics and imaging. The expression of the excitatory opsin, ReaChR, in vascular smooth muscle cells enabled rapid and repeated vasoconstriction following brief light pulses. Targeted two-photon activation of ReaCHR using a spatial light modulator (SLM) produced highly localized constrictions when targeted to individual arteries within the neocortex. We demonstrate the utility of this method for examining arteriole contractile dynamics and creating transient blood flow reductions. Additionally, we show that optogenetic constriction can offset or completely block sensory stimulus evoked vasodilation, providing a valuable tool to dissociate blood flow changes from neural activity.

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Up-regulation of endometrial oxytocin receptor is associated with the timing of luteolysis in heifers with two and three follicular waves†

Biology of Reproduction ◽

10.1093/biolre/ioz165 ◽

2019 ◽

Vol 102 (2) ◽

pp. 316-326 ◽

Cited By ~ 1

Author(s):

Rafael R Domingues ◽

O J Ginther ◽

Victor E Gomez-León ◽

Milo C Wiltbank

Keyword(s):

Blood Flow ◽

Steroid Receptors ◽

Progesterone Receptors ◽

Oxytocin Receptor ◽

Control Group ◽

Follicular Waves ◽

Receptor Mrna ◽

Estradiol Receptors ◽

And Control

Abstract Initiation of luteolysis in ruminants is variable due to ill-defined mechanisms. Cycles of two follicular waves are shorter and have earlier luteolysis than three-wave cycles. This study validated a cytobrush technique for evaluating dynamics of endometrial gene expression and associated changes in mRNA with timing of luteolysis, based on circulating progesterone and ultrasound-determined changes in blood flow and volume of corpus luteum (CL). On day 8 (ovulation = day 0), Holstein heifers were randomized into two groups: cytobrush group (n = 9) had an endometrial sample collected every 48 h from day 8 until end of luteolysis (CL blood flow ≤ 20%) and control group was sampled only once either before (day 12; n = 4) or at the end of luteolysis (n = 5). Concentrations of progesterone, CL blood flow, CL volume, and the frequency of two and three-wave cycles were similar between groups. Endometrial mRNA for progesterone receptors and estradiol receptors 1 and 2 was greater on day 8 and decreased thereafter similarly in two and three-wave cycles. Oxytocin receptor mRNA increased earlier in two vs three-wave cycles (day 14 vs 18), and the increase was associated with the onset of luteolysis. In conclusion, the cytobrush technique allowed in vivo collection of multiple endometrial samples during the estrous cycle. Endometrial mRNA expression of steroid receptors did not explain the variability in timing of onset of luteolysis in heifers while the later onset of luteolysis in three-wave cycles was associated with later up-regulation of oxytocin receptor mRNA.

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120 Blood flow is required for endothelial repair in a novel in vivo model using zebrafish embryos

Heart ◽

10.1136/heartjnl-2012-301877b.120 ◽

2012 ◽

Vol 98 (Suppl 1) ◽

pp. A68.1-A68

Author(s):

N M Quaife ◽

T J A Chico

Keyword(s):

Blood Flow ◽

In Vivo Model ◽

Zebrafish Embryos ◽

Endothelial Repair

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Lung antioxidant enzymes are regulated by development and increased pulmonary blood flow

AJP Lung Cellular and Molecular Physiology ◽

10.1152/ajplung.00449.2006 ◽

2007 ◽

Vol 293 (4) ◽

pp. L960-L971 ◽

Cited By ~ 24

Author(s):

Shruti Sharma ◽

Albert C. Grobe ◽

Dean A. Wiseman ◽

Sanjiv Kumar ◽

Manal Englaish ◽

...

Keyword(s):

Blood Flow ◽

Pulmonary Hypertension ◽

Antioxidant Enzymes ◽

Pulmonary Blood Flow ◽

Expression Patterns ◽

Antioxidant Systems ◽

Therapeutic Implications ◽

Protein Levels ◽

And Control

Increasing data suggest that oxidative stress, due to an increased production of reactive oxygen species and/or a decrease in antioxidants, is involved in the pathophysiology of pulmonary hypertension. Several antioxidant systems regulate the presence of oxidant species in vivo, and of primary interest are the superoxide dismutases (SOD) and catalase. However, little is known about the expression of antioxidant enzymes during the development of pulmonary hypertension. This study uses our lamb model of increased postnatal pulmonary blood flow, secondary to in utero aortopulmonary graft placement (shunt lambs), to investigate the expression patterns as well as activities of antioxidant enzymes during the early development of pulmonary hypertension. Protein levels of catalase, SOD1, SOD2, and SOD3 were evaluated by Western blot, and the activities of catalase and SOD were also quantified. In control lambs, protein expression and activities of catalase and SOD2 increased postnatally ( P < 0.05). However, SOD1 and SOD3 protein levels did not change. In shunt lambs, catalase, SOD1, and SOD2 protein levels all increased over the first 8 wk of life ( P < 0.05). However, SOD3 did not change. This was associated with an increase in the activities of catalase and SOD2 ( P < 0.05). Compared with control lambs, catalase and SOD2 protein levels were decreased in 2-wk-old shunt lambs and this was associated with increased levels of hydrogen peroxide (H2O2) and superoxide ( P < 0.05). Developmentally superoxide but not H2O2 levels significantly increased in both shunt and control lambs with levels being significantly higher in shunt compared with control lambs at 2 and 4 but not 8 wk. These data suggest that the antioxidant enzyme systems are dynamically regulated postnatally, and this regulation is altered during the development of pulmonary hypertension secondary to increased pulmonary blood flow. An increased understanding of these alterations may have important therapeutic implications for the treatment of pulmonary hypertension secondary to increased pulmonary blood flow.

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Microvascular features that suggest effectors of blood-flow regulation in the brain: Evidence by SEM of corrosion casts of intracerebral vessels

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100158923 ◽

1990 ◽

Vol 48 (3) ◽

pp. 274-275

Author(s):

Enrico D.F. Motti ◽

Hans-Georg Imhof ◽

Gazi M. Yasargil

Keyword(s):

Blood Flow ◽

Perfusion Pressure ◽

Corrosion Casts ◽

Cerebral Microcirculation ◽

Pial Arteries ◽

Random Occurrence ◽

Brain Arteries ◽

Homogeneous Network ◽

The Brain

Physiologists have devoted most attention in the cerebrovascular tree to the arterial side of the circulation which has been subdivided in three levels: 1) major brain arteries which keep microcirculation constant despite changes in perfusion pressure; 2) pial arteries supposed to be effectors regulating microcirculation; 3) intracerebral arteries supposed to be deprived of active cerebral blood flow regulating devices.The morphological search for microvascular effectors in the cerebrovascular bed has been elusive. The opaque substance of the brain confines in vivo investigation to the superficial pial arteries. Most morphologists had to limit their observation to the random occurrence of a favorable site in the practically two-dimensional thickness of diaphanized histological sections. It is then not surprising most investigators of the cerebral microcirculation refer to an homogeneous network of microvessels interposed between arterioles and venules.We have taken advantage of the excellent depth of focus afforded by the scanning electron microscope (SEM) to investigate corrosion casts obtained injecting a range of experimental animals with a modified Batson's acrylic mixture.

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