bluuebunny/crossref_metadata_2025_split huggingface dataset:
Role Of Gamma‐Adducin Gene In Cerebral Vascular Myogenic Response
Authors: Pabbidi Mallikarjuna , Ge Ying , Harder David R , Roman Richard J , Fan Fan 
Published: November 2023

Previous studies suggest that middle cerebral arteries (MCA) isolated from FHH rat exhibit impaired myogenic response (MR) that is associated with elevation in large conductance potassium (BK) channel function. Impaired MR is restored in FHH.1BN congenic strain in which 2.4‐Mbp region containing 15 genes including Gamma‐adducin (Add3) in chromosome 1 from BN rats is transferred onto FHH rat. The present study tested the hypothesis that a mutation in Add3 gene, is responsible for the elevation of BK channel function that contribute to impaired vascular MR in FHH rats. We used 27‐mer Dicer‐Substrate RNAi (DsiRNA) to silence Add3 gene in cerebral vessels and HEK293 cells that are permanently transfected with BKα subunit to measure vascular function and BK channel function respectively using arteriomyography, patch clamp and western blot methods. MCA transfected with Add3 DsiRNA and cultured for 36hrs reduced mRNA expression in a dose‐dependent manner (50±0.2% reduction; n=3). MCA transfected with Add3 DsiRNA exhibited impaired MR when luminal pressure is increased from 50 to 150 mmHg (112±1 to 121±2μm; n=3). In contrast, the MR is intact in vessels treated with scrambled DsiRNA (50mmHg: 131±16 to 150mmHg: 91±5 μm; n=3). Total outward K channel currents were ~3 fold higher in smooth muscle cells freshly isolated from MCA that were transfected with Add3 DsiRNA compared with non‐transfected cells (DsiRNA:141±18 pA/pF; non‐ transfected: 44±10 pA/pF; n=10–11). Similarly, BK channel current was ~3 fold higher in HEK293 cells expressing BKα that were transfected with Add3 DsiRNA (+120mV; DsiRNA: 334±8 pA/pF; non‐ transfected: 109±17 pA/pF; n=3–4). Finally, expression of BKα protein is ~2 fold greater in the membrane of cerebral vessels isolated from FHH compared to FHH.1BN rats (FHH: 2.6±0.5; FHH.1BN: 1.3±0.1; n=3). In conclusion, these results indicate that Add3 is a viable candidate gene that may play a causal role in impaired MR by elevation of BK channel activity in FHH rats.Support or Funding InformationThis research has received funding support from the American Heart Association, Scientist Development Grant (13SDG14000006) to Pabbidi and NIH 1R01DK104184‐01 to Richard J. Roman.
Effects of Muscle Stretching on Skeletal Muscle Microcirculation in Old Rats
Authors: Hotta Kazuki , Behnke Bradley J , Ghosh Payal , Chen Bei , Churchill Alexandra , Elam Marcus L , Pourafshar Shirin , Arjmandi Bahram H , Maher Patrick , Kurien Daniel , Verma Rahul , Christou Demetra , Muller‐Delp Judy M 
Published: November 2023

Skeletal muscle blood flow during exercise declines with age, in part, due to impaired microvascular dysfunction of skeletal muscle. Mechanical stretch alters morphology and function of vascular endothelial cells; however, little is known about the effect of muscle stretching on endothelium‐dependent vasodilation and skeletal muscle microcirculation. We tested the hypothesis that daily passive muscle stretching enhances endothelium‐dependent vasodilation of skeletal muscle arterioles and increases skeletal muscle blood flow in old rats. Old (n=45, 20 months old) male Fischer 344 rats underwent daily muscle stretching or remained cage controls. The left hindlimb was passively stretched by placing a splint on the left ankle (30 min/day, 5d/wk for 4 wks). The right hindlimb served as a contralateral control limb. At the end of the muscle stretching, soleus muscle blood flow was measured at rest and during treadmill exercise. The relaxation responses to acetylcholine was assessed in isolated soleus muscle arterioles. Three dimensional images of the microvasculature in soleus muscle were obtained using a high‐resolution microcomputed tomography. Exercising blood flow and relaxation responses to acetylcholine were greater in soleus muscle of the stretched hindlimb as compared with the contralateral hindlimb and cage control rats. Microcomputed tomography imaging of vessel connectivity, which is defined as the number of vessel branches, was greater in soleus muscle of the stretched hindlimb than the contralateral hindlimb. These results suggest that muscle stretching enhances microvascular endothelial function and induces angiogenesis, likely contributing to increased exercising blood flow in skeletal muscle of old rats.Support or Funding InformationNIH 1R 21AG044858‐01A1 and Japan Heart Foundation
Acute Reduction of Ambient Air Pressure Enhances Arterial Vasodilation in Murine Resistance Arteries Independently of Endothelial Factors
Authors: Shahid Anmol , Morton Jude S , Davidge Sandra T , McMurtry Michael Sean 
Published: November 2023

IntroductionEpidemiological studies have found populations living at higher elevations are at lower risk for acute myocardial infarction (MI) than those at lower elevations, even after adjustments for confounders. The mechanism for this observation is not known. Since atmospheric air pressure varies inversely with elevation, and air pressure exerts compressive force on vascular structures, reduced compressive force on arteries due to elevation‐related reductions in atmospheric pressure might alter arterial function. This could be a potential mechanism. We hypothesized that acute exposure to lower air pressure will dilate arteries and increase arterial vasodilation to reduce peripheral vascular resistance.MethodsSecond order mesenteric arteries (n=7) were isolated from C57BL/6 male mice (n=7, age 3.2±0.9 months) and perfused with Ca2+‐free saline solution to assess passive properties of the vessels in a pressure myograph. This system was placed in a custom‐designed hypobaric chamber and arterial function was studied ex‐vivo at acute exposure to three barometric pressure steps: 754 mmHg (room pressure or control), 714 mmHg (p1) and 674 mmHg (p2). Active vessel responses in the presence of L‐NAME, a nitric oxide inhibitor, and Meclofenamate, a cyclooxygenase inhibitor, were assessed with mechanical manipulation of perfusion pressure (4–140 mmHg) or flow rate (0–70 μL/min). Lumen diameter was measured using a micrometer, with manometers for measurement of pressure drop across the vessel.ResultsUnder static conditions, vessel diameters at p1 and p2 increased by 20.9±9.3% and 28.2±8.6% compared to baseline diameter at room pressure (p<0.01 vs. control for p1 and p2). Flow‐mediated vasodilation contributed little additional dilation. At a fixed flow rate of 70 μLmin−1, vessels reached maximum diameters of 108.6 ±13.6μm at p1 and 120.5±13.0 at p2 versus 106.0±4.0 μm for the control condition. This observed vasodilation was not diminished in the presence of L‐NAME and Meclofenamate. Vascular resistance was significantly reduced at p2 compared to control (2.14±0.60 mmHg*min/μL vs. 3.21±0.49 mmHg*min/μL, p < 0.05).ConclusionWe conclude that acute exposure to reduced barometric pressure increases artery diameter and decreases resistance across vessels ex‐vivo in an endothelium‐independent manner.
Comprehensive Hemodynamic Analysis of Arteriolar Networks in the Rat Gluteus Maximus Muscle
Authors: Al Tarhuni Mohammed , Jackson Dwayne N , Goldman Daniel 
Published: November 2023

IntroductionTheoretical blood flow models enable comprehensive analysis of blood flow, pressure, resistance, and hematocrit distribution within microvascular networks. However, the validity of data produced by such models is dependent on the detail of its experimentally derived inputs. Currently, many theoretical models of skeletal muscle hemodynamics are limited to incorporating experimental inputs from small network segments or trees, or from non‐locomotive tissues such as the mesentery. Thus, the objective of this study was to utilize recently collected experimental (geometric and topological) data from complete arteriolar networks of locomotive skeletal muscle as inputs for our computational blood flow model. Using outputs from theoretical simulations, we evaluated inter‐network hemodynamic variability in an effort to describe the level of functional homology among skeletal muscle arteriolar networks.MethodsThe rat GM provides the ideal experimental model to study locomotive skeletal muscle. Its planar geometry and uniform thinness enable access (within a single focal plane) to its entire microcirculation for microscopic imaging and perturbation. Using intravital videomicroscopy, the GM (n=4) was scanned under baseline conditions and photomontages were compiled (~400 images per network). Photomontages were registered to a MATLAB x–y coordinate system and scaled digital networks were generated. Approximately 1500 discrete nodes were used to mathematically model each network, with an average length of approximately 100 μm between each node, resulting in 179 to 239 vessel segments per network. A previously established two‐phase blood flow model (MATLAB) was used to simulate and assess the hemodynamic properties of each arteriolar network including heterogeneity within each network and variability between networks.ResultsBlood flow rate in each vessel segment decayed exponentially with increasing (1A to 9A) arteriolar order for each network (Exponential Decay fit: R2 0.71 to 0.88). Additionally, the coefficients of variation (a measure of blood flow distribution) at each order ranged from 30.24% to 86.79%. Log‐log plots between blood flow and arteriolar diameter showed a strong correlation for each network (Linear Regression, R2 0.65 to 0.86) with similar slopes of regression lines (3.08 to 3.81).ConclusionSimulation results show strong homology in blood flow properties between all the networks considered. Other hemodynamic properties such as RBC flow and hematocrit, as well as overall resistance, are now being analyzed with respect to both arteriolar order and diameter. This analysis allows detailed comparison of the hemodynamic properties of the different arteriolar networks studied, including the extent to which observed topological and geometric homologies result in similar hemodynamic outcomes.Support or Funding InformationNSERC
Endothelial Dysfunction in Children after Cardiopulmonary Bypass
Authors: Krispinsky Luke , Lamb Fred , Stark Ryan , Parra David 
Published: November 2023

ObjectivesCardiopulmonary bypass (CPB) is required for surgical repair of congenital heart defects; however, CBP causes an inflammatory response which profoundly impacts post‐operative management. CBP‐induced endothelial dysfunction has been inferred by changes in pulmonary vascular resistance, changes in biomarkers, and the presence of capillary leak. However, peripheral vascular endothelial dysfunction has never been quantified in children. We used laser Doppler perfusion monitoring (LDPM) coupled with iontophoresis of vasoactive compounds to assess endothelial function in cutaneous arterioles in infants undergoing CPB.Study DesignEnrollment criteria included age less than 1 year and a congenital heart lesion requiring use of CPB. Timing of assessment of endothelial function included pre‐operatively, 2–4 hours and 24 hours after CPB. Trans‐cutaneous iontophoresis of acetylcholine (ACh, endothelium‐dependent vasodilator) was used to trigger increases in local perfusion and LDPM signals were quantified as peak perfusion and area under the curve (AUC). Sodium nitroprusside (NP) provided an endothelium independent control vasodilator. With each assessment of endothelial function, estimates of extracellular water were obtained using bioelectrical impedance analysis. Clinical markers of the severity of postoperative illness were obtained through chart review. Peak serum lactate, total colloid and crystalloid replacement volume, urine output, and peak vasoactive inotrope score will be correlated with the degree of endothelial impairment. Means and standard error of the mean were calculated for peak perfusion and AUC to determine if there was significant change between pre and post‐CPB values.Results15 patients have completed the study protocol. Comparing pre‐bypass LDPM responses to ACh with initial (2–4 hour) post‐bypass measurements, we observed a significant decrease in both the peak perfusion values (75.6 ± 10.7 vs. 32.3 ± 7.7 perfusion units (PU), p < 0.05) as well as the AUC (19,417 ± 3286 vs. 6980 ± 2197 PU, p < 0.05). The percent change from baseline responses to ACh at 2–4 hours post‐CPB was −56% ± 8.8% for peak values and −61% ± 11% for AUC. Responses to ACh 24 hours after CBP remained impaired, but this effect was not statistically significant. In contrast, responses to NP were not significantly altered at 2–4 or 24 hours post‐CPB. Analysis of LDPM correlation to biochemical and clinical outcomes is ongoing.ConclusionProfound cutaneous vasomotor endothelial dysfunction is present in infants 2–4 hours after separating from CPB. This effect may persist for at least 24 hours. The clinical significance of this finding remains to be determined.Support or Funding InformationDr. Fred Lamb's Laboratory at Vanderbilt Children's Hospital
Effects of Hydrogen Sulfide on Renal and Mesenteric Blood Flow
Authors: Barrera Adelaeda , Naik Jay , Kanagy Nancy L. 
Published: November 2023

In sleep apnea, recurrent obstruction of the upper airway leads to sleep fragmentation and intermittent hypoxia (IH) during sleep. In animal studies, IH causes wake‐time hypertension by elevating vascular resistance due in part to decreased production of the vasodilator, hydrogen sulfide (H2S). Inhibiting cystathionine γ‐lyase (CSE) to prevent H2S synthesis augments constriction in isolated mesenteric and renal arteries but H2S regulation of resistance in these vascular beds in vivo is unknown. The goal of this study was to evaluate CSE regulation of flow and resistance in the mesenteric and renal circulations of control rats and in rats made hypertensive by exposure to IH for 14 days. We hypothesized that inhibiting CSE would increase vascular resistance and mean arterial pressure (MAP) more in Sham than in IH exposed rats. Rats were anesthetized with inhaled isofluorane (2%) and instrumented with femoral artery and vein catheters and Doppler flow probes on the main mesenteric and renal arteries. Responses to phenylephrine and CSE inhibition (β‐cyanoalanine, BCA, 50 mg/kg/min infusion for 20 minutes) were evaluated. BCA infusion significantly increased MAP in both Sham and IH compared to saline infusion (Sham: 7.2±1.2 vs. −2.8±1.1; IH: 9.3±1.1 vs. 3.3±0.7, % change from baseline, p<0.05, n=6–8 rats per group) and augmented the press or response to phenylephrine (12 mg/kg, bolus) in Sham, but not IH rats. However, BCA did not alter either renal or mesenteric resistance in the Sham and IH groups. Thus, CSE is an important regulator of blood pressure and reduces sensitivity to adrenergic stimulation. However, since resistance arteries were not sensitive to CSE inhibition in anesthetized rats, future studies in conscious animals will determine if this was due to effects of anesthesia or lack of regulation of vascular tone by H2S in these vascular beds.Support or Funding InformationThis work was supported by the National Institutes of Health National Heart, Lung, and Blood Institute [Grants HL123301 and HL007736‐21] and institutional funding from the University of New Mexico.
Inhibition of TRPC3 Channels Underlies Hypoxia/Reoxygenation‐induced Endothelial KCa Channel Dysfunction
Authors: Wang Xiang‐Chong , Huang Jun‐Hao , Sun Wen‐Tao , Yu Cheuk‐Man , He Guo‐Wei , Yang Qin 
Published: November 2023

ObjectivesAlthough studies have shown that elevation of [Ca2+]i is essential for the activation of endothelial calcium‐activated potassium (KCa) channels and the importance of Ca2+‐permeable channels, such as canonical transient receptor potential channel (TRPC) in endothelial [Ca2+]i regulation, little information is available regarding the association of TRPC and KCa channels in endothelial function. Furthermore, it remains uninvestigated whether modulation of TRPC channels is involved in the compromised endothelial function related to IKCa and SKCa in ischemia/reperfusion injury.MethodsVasorelaxation was studied in porcine small coronary arteries (PCAs) in a myograph. IKCa and SKCa channel currents were recorded by patch‐clamp, and coimmunoprecipitation experiments were performed to examine the association of TRPC3 and KCa proteins in primary cultured porcine coronary arterial endothelial cells (PCAECs).ResultsThe IKCa and SKCa‐dependent, endothelium‐derived hyperpolarizing factor (EDHF)‐mediated relaxation in response to bradykinin was inhibited in PCAs pretreated with the TRPC3 specific inhibitor Pyr3. Pharmacological inhibition of TRPC3 with Pyr3 and TRPC3 gene silencing by siRNA both significantly suppressed bradykinin‐induced IKCa (6.71±0.85 in Pyr3‐treated cells, 9.46±1.12 in TRPC3 siRNA transfected cells, vs. 16.89±0.93 pA/pF in control) and SKCa (5.51±1.17 and 6.46±0.84, vs. 10.63±1.69 pA/pF) currents. No physical interactions between either TRPC3 and IKCa channels or TRPC3 and SKCa channels were observed. In hypoxia/reoxygenation (H/R)‐exposed PCAECs, bradykinin‐induced IKCa (10.24±1.96 pA/pF) and SKCa (4.62±0.43 pA/pF) currents were markedly suppressed and Pyr3 exhibited less inhibition on both components when compared with the cells without H/R exposure. Activation of TRPC3 channels with 1‐oleoyl‐2‐acetyl‐sn‐glycerol (OAG) restored H/R‐induced suppression of IKCa (15.08±0.99 pA/pF) and SKCa (9.62±0.89 pA/pF) currents and the current enhancement is associated with an improved EDHF response in PCAs.ConclusionsTRPC3 channels play an important role in IKCa and SKCa channel activation in coronary arterial endothelial cells. The functional association between TRPC3 and KCa channels does not involve physical interaction. Inhibition of TRPC3 channels contributes to H/R‐induced suppression of IKCa and SKCa channel activity, which serves as a mechanism underlying endothelial dysfunction under H/R condition and renders TRPC3 channels a potential target for endothelial protection in ischemic status.Support or Funding InformationSupported by RGC/GRF CUHK4774/12M & CUHK14118414; Lui Che Woo Institute of Innovative Medicine ‐ CARE theme 8303303, and CUHK Direct Grant 4054182.
Rapid Increases in Fluid Shear Stress Elicit Local Lamellipodia and Elevate Microvascular Endothelial Barrier Function
Authors: Spampinato Sara G , Breslin Jerome W 
Published: November 2023

The microvascular endothelium serves as a barrier that controls exchange of fluid and solutes between the blood and tissues. This semipermeable barrier reacts to changes in frictional shear stress from the plasma as it flows over the luminal surfaces of endothelial cells. We tested the hypothesis that step increases in shear stress strengthen endothelial barrier function, due to spreading of endothelial cell membrane near junctions. We also tested the role of the shear stress‐sensing calcium channel Piezo1 in both baseline and mediating shear‐dependent changes in barrier function. An electrical cell substrate impedance sensor (ECIS) was used to determine the barrier function of cultured human cardiac microvascular endothelial cell (HCMEC) monolayers, with transendothelial electrical resistance (TER) serving as an index of barrier integrity. Shear stress was stepped from either 0 or 1 dynes/cm2 up to 10 dynes/cm2 using a computer‐controlled peristaltic pump system. Time‐lapse microscopic images of confluent HCMEC monolayers were obtained to observe junctions and spreading behavior of cells. The number of local lamellipodia per 100 microns of junctional distance over time, before and after step increases in shear stress, was quantified. The Piezo1 inhibitor, GSMTx4 was applied at 1.25 mM for at least 30 min under no‐flow conditions prior to testing step increases in shear stress. The results show that step increases in shear stress cause an increase in TER, that correlates with a robust increase in local lamellipodia. GSMTx4 caused a significant decrease in TER within the first few minutes of application. Step increases in shear stress applied after GSMTx4 still caused increases in TER, but usually not up to the level observed prior to GSMTx4 treatment. Combined, the data shows that rapid changes in fluid shear stress elicit a quick rise in the number of local lamellipodia that protrude from endothelial cells, that appear to tighten the junctions between cultured endothelial cells. The results also suggest that the Piezo1 channel has a role in maintaining basal barrier function of endothelial cells. However, endothelial cells can still enhance their barrier function when Piezo1 is blocked using GSMTx4. Because a compromised endothelial barrier is common in many diseases and after injury, our future goal will be to identify mechanisms that promote local lamellipodia as potential therapeutic targets.Support or Funding InformationSupported by NIH Grant R01HL098215‐S1
Lymphatic Vascular Integrity is Disrupted in a Mouse Model of Diabetes: Dual Regulation by Nitric Oxide
Authors: Scallan Joshua P , Hill Michael A , Davis Michael J 
Published: November 2023

Emerging studies support the idea that metabolic diseases such as hypercholesterolemia and obesity are associated with compromised lymphatic vessel function. Whether, or how, insulin‐resistant diabetes affects the lymphatic vasculature remains unexplored. To test the hypothesis that lymphatic vascular integrity is disrupted in diabetes, we developed an innovative approach to measure the permeability of collecting lymphatics from wild‐type (WT) and leptin receptor‐deficient (db/db) mice. Vessels were isolated and mounted on glass micropipettes that could switch repeatedly between perfusion of fluorescent‐labeled or unlabeled albumin solutions. The accumulation of fluorescent albumin outside the vessel was measured over time with photometry, while diameter was monitored simultaneously on a near infrared image. Since nitric oxide (NO) is crucial for maintaining blood vessel integrity and is impaired in diabetes, we first determined whether NO was capable of regulating lymphatic permeability (×10(−7) cm/s). WT lymphatic permeability (3.3±0.7, n=7) was significantly reduced by pharmacologic inhibition (0.6±0.2, n=7) or genetic deletion (0.6±0.1, n=6) of endothelial nitric oxide synthase (eNOS). Histamine, an agent known to elicit endogenous NO production (21±7, n=7), or sodium nitroprusside, an exogenous NO donor (20±5, n=6), both significantly elevated WT lymphatic permeability. Collecting lymphatics from db/db mice exhibited a dramatic increase in permeability compared to age‐matched 25‐week old controls (WT: 2.2±0.3, n=10; db/db: 299±56, n=23). Interestingly, restoration of NO production by acute exposure to L‐arginine rescued this endothelial barrier dysfunction, and could be reversed by pharmacologic inhibition of eNOS with L‐NAME (db/db: 321±84, L‐arginine: 14±5, L‐arginine+L‐NAME: 297±88; n=9). In summary, this approach enables quantitative measurement of lymphatic integrity in transgenic mice for the first time and identified a lymphatic defect in diabetic mice caused by reduced NO bioavailability.Support or Funding InformationThis work was supported by the National Heart, Lung, and Blood Institute at the National Institutes of Health (K99 HL124142 to J.P.S., R01 HL089784 and R01 HL120867 to M.J.D., P01 HL095486 to M.J.D. and M.A.H., and R01 HL085119 to M.A.H.)