bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract 496: Evaluation of Some Hemostatic Parameters in Patients With End-Stage Renal Disease: Relation to Dyslipidemia and Hemodialysis Therapy
Authors: Abousamra Nashwa , Sayed-Ahmed Nagy , Hegazy Asmaa , Selim Tarek , Azzam Hanan , ELShaarawy Solafa
Published: March 2022

Background:
Patients with end stage renal disease (ESRD) are prone to hemorrhagic complications and simultaneously at risk for a variety of thrombotic complications. Abnormal lipid metabolism and endothelial cell injury are considered as potential risk factors for atherothrombosis in these patients. This study assessed the status of some hemostatic parameters in ESRD patients and define their relation to lipid profile and hemodialysis therapy.

Patients and Methods:
Twenty-four patients with end-stage renal disease were selected for the study (Ten of them were under conservative treatment and fourteen were under regular hemodialysis therapy).Ten age-and gender-matched healthy subjects were recruited as a control group. All patients and controls were subjected to routine laboratory work up as well as measurement of plasma lipids, prothrombin time (PT), activated partial thromboplastin time (APTT), fibrinogen, soluble fibrin monomer, ADP-induced platelet aggregation, plasminogen and plasminogen activator inhibitor-1 (PAI-1).

Results:
We found statistically significant increase of triglycerides, LDL-C, fibrinogen and PAI-1 levels, prolongation of APTT and significant decrease of HDL-C level, platelet count, prothrombin activity and impairment of platelet aggregation response to ADP in ESRD patients compared to controls (P< 0.05). Furthermore, we demonstrated a significant increase of platelet count in dialyzed compared to undialyzed ESRD patients (P<0.05). Also we found a significant negative correlation between serum triglyceride level and plasminogen concentration (r = -0.644 ; P = 0.044) and between LDL-C levels and platelet count (r = - 0.709 ; P = 0.022) in undialyzed ESRD patients.

Conclusions:
Profound changes of hemostasis and plasma lipids do exist in ESRD patients and is not significantly corrected by hemodialysis therapy. Elevated fibrinogen level, low PAI-1 level and hypertriglyceridemia might contribute to hypercoagulability in ESRD patients which is not ameliorated significantly by the currently used hemodialysis therapy. Newer methods of dialysis or more biocompatible filters or techniques may offer potential benefits in these conditions.
Abstract 497: The Influence of Long Term Voluntary Exercise on Cardiac Autonomic Function in Conscious Chronic Kidney Disease Animals
Authors: Kandukuri Divya S , Hildreth Cara M , Goodchild Ann K , Nalivaiko Eugene , Phillips Jacqueline K
Published: March 2022

Background:
Chronic kidney disease (CKD) is associated with an increased risk of cardiovascular morbidity and mortality. Exercise has enduring cardio-protective effects that arise, in part, as a result of improved autonomic control of heart rate (HR). The aim of our study was to determine if voluntary exercise improves autonomic function in conscious animals with CKD, specifically examining the balance between sympathetic and parasympathetic cardiac tone.

Methods:
Mixed sex Lewis and Lewis polycystic kidney disease (LPK) rats were used. Animals were divided into four groups: sedentary Lewis (SL) (n=4); exercise Lewis (EL) (n=3); sedentary LPK (SLPK) (n=2); and exercise LPK (ELPK) (n=2). The exercise group was provided unlimited access to an activity wheel in their home cage from 5 weeks of age, and the sedentary group a locked activity wheel. At 10 weeks of age, rats were implanted with radio-telemetry probes. At 13 weeks, resting HR, mean blood pressure (MBP) and activity were determined over a 20 minute period during the day and changes in HR in response to atenolol (AT, 1 mg/kg i.p.) and methylatropine (MA, 2 mg/kg, i.p.).

Results:
Resting HR and activity was not significantly different between any groups. MBP was higher in both ELPK and SLPK compared with Lewis (average: 213.4 ± 3.8 vs. 96.8 ± 2.8 mmHg,
P
<0.05). In the ELPK compared to SLPK, atenolol produced a smaller reduction in HR (-47.5 ± 0.8 vs. -66.9 ± 2.8 bpm,
P
<0.05) and methylatropine a greater increase in HR (85.8 ± 5.3 vs. 54.9 ± 5.1 bpm,
P
<0.05) indicating a relative reduction in sympathetic and increase in vagal tone in the exercised animals. This was not observed in the Lewis rats.

Conclusion:
Our preliminary data demonstrates that exercise promotes vagal control of HR in rodents with CKD. Future studies will identify if this translates to an improvement in baroreflex control of HR.
Abstract 501: Enhanced Expression of the Endocannabinoid 2-AG and CB-1 Receptor in the Kidney of the Diabetic Hypertensive Female Rat
Authors: Hukuda Deborah , de Lima Hariane , Pirro Nancy T , Yamaleyeva Liliya M , Grabenauer Megan A , Thomas Brian T , Chappell Mark C
Published: March 2022

The cannabinoids arachidonoylethanolamide (AEA) and 2-arachidonoylglycerol (2-AG) are endogenous ligands for the cannabinoid receptors including CB1 and CB2 subtypes. The endocannabinoid system (ECS) is typically associated with regulation of metabolic balance and appetite, although CB1 receptors (CB1R) may contribute to diabetic renal injury while CB2R are protective. The hypertensive mRen2.Lewis (mRen2) females have less renal injury than the males; however, diabetic female mRen2 lack this protection and show comparable indices of injury to the diabetic males. The present study addressed whether female and male diabetic mRen2 exhibit similar alterations in the renal ECS. Diabetes was induced with a single dose of streptozotocin (STZ at 65 mg/kg; ip). Cortical content of AEA and 2-AG was quantified by UPLC MS/MS. Receptor levels and the metabolizing enzymes for AEA (FAAH) and 2-AG (MAGL) were quantified by protein immunoblot. Basal 2-AG content was higher in male versus female mRen2, and significantly increased in both diabetic females and males (figure, n=6) while AEA was unchanged. Cortical Ang II correlated to 2-AG [p<0.01; r = 0.89]. CB1R protein expression was higher in female diabetic mRen2 but unchanged in the males (figure, n=4). CB2R expression was lower in the male diabetics [p<0.01; n=4], but not changed in females. MAGL expression was >70% lower in female diabetics compared to controls [p<0.05; n=4] while FAAH was not changed. Elements of the renal ECS are differentially regulated in the diabetic mRen2. Higher expression of both 2-AG and CB1R, but reduced MAGL (females) and CB2R (males) may contribute to the development and progression of renal injury in this model.
Abstract 502: Enhanced Tubular Chymase Protein Expression in Diabetic Kidneys Activates the Epithelial Sodium Channel (ENaC)
Authors: Ford Stephen M , Wood Kirsten A , Berner Paul M , Naqvi Nawazish , Husain Ahsan , Kashlan Ossama B , Kleyman Thomas R , Harrison-Bernard Lisa M
Published: March 2022

We tested the hypothesis that enhanced tubular chymase protein expression in diabetic kidneys activates the epithelial sodium channel (ENaC). Diabetic (
db/db)
and control (
db/m
) mice were studied during prediabetes, type II diabetes, and progression to type I diabetes at 5-, 18-, and 36-wks of age, respectively. In 5-wk-old diabetic (n=11), body weights (25.6 ± 0.7 vs 20.3 ± 0.6 g) were significantly increased, while plasma glucose (143 ± 29 vs 160 ± 13 mg/dL) and insulin (1.2 ± 0.1 vs 1.2 ± 0.1 μg/L) levels were not different than control (n=11) mice. In 18-wk-old diabetic (n=8) mice, body weights (53.7 ± 0.7 vs 29.7 ± 0.3 g), blood glucose (400 ± 16 vs 137 ± 6 mg/dL), and insulin (20 ± 6 vs 1.9 ± 0.7 μg/L) levels were increased compared to control (n=9) mice. In 36-wk-old diabetic (n=7), body weights (33 ± 3 vs 40 ± 2 g) were decreased, plasma glucose levels (552 ± 40 vs 220 ± 21 mg/dL) increased, and insulin levels (0.8 ± 0.1 vs 0.4 ± 0.1 μg/L) not different from control (n=8) mice. Immunohistochemistry revealed chymase localization to apical membranes of principal cells of connecting tubules and collecting ducts. Densitometric analyses revealed that diabetic renal papillary chymase immunostaining levels were 4 to 28 fold higher relative to control papilla at all ages (p≤0.05). In 5-wk-old diabetic mice, renal cortical chymase expression was increased 1.8 ± 0.3 fold, but decreased to 0.5 ± 0.1 fold in 36-wk-old diabetic compared to control mice (p≤0.05). Relative amiloride-sensitive Na
+
currents were increased by chymase (5 μg/mL) perfused
Xenopus laevis
oocytes injected with α-, β-, and γ- ENaC (1.57 ± 0.08; n=6) relative to mock control (1.13 ± 0.02; n=3) oocytes (p≤0.01). In conclusion, these are the first studies to demonstrate chymase protein localization to the ENaC expressing principal cells of the distal nephron. Papillary chymase expression is unique to prediabetic and diabetic kidneys and does not correlate with glycemia, insulinemia, or body weight. Elevated renal chymase expression may serve as an early biomarker for prediabetic patients with a high risk of developing diabetic renal disease. Enhanced chymase activity, associated with diabetes mellitus, may increase ENaC activity, potentially leading to hypertension and diabetic renal disease.
Abstract 511: Endothelial Cell-specific Liver Kinase B1 Deletion Causes Hypertension in Mice in vivo
Authors: Zhang Wencheng , Zou Ming
Published: March 2022

Background-
Liver kinase B1 (LKB1), a tumor suppressor, is a central regulator of cell polarity and energy homeostasis. The roles of LKB1 in endothelial function
in vivo
have not been explored.

Methods and Results-
The endothelium-specific LKB1 knockout (

LKB1
endo

-/-

) mice were generated by crossbreeding LKB1
flox/flox
mice with VE-cadherin Cre approach.

LKB1
endo

-/-

mice exhibited hypertension, cardiac hypertrophy and impaired endothelium-dependent relaxation. In addition, in parallel with reduced levels of both endothelial nitric oxidase (eNOS) activity and phosphorylated (Thr172) AMP-activated protein kinase (AMPK), a downstream enzyme of LKB1,

LKB1
endo

-/-

mice expressed high levels of caveolin-1. Further, siRNA silencing of caveolin-1 normalized the eNOS activity in LKB1-deficient endothelial cells. Furthermore, human antigen R (HuR) bound with AU-rich elements of caveolin-1 mRNA 3’ UTR resulting in increased stability of caveolin-1 and genetic knockdown of HuR decreased caveolin-1 level in LKB1-deficient endothelial cells. Finally, we found that inhibition of LKB1 or AMPK induced the translocation of HuR from nuclei to cytosol and overexpression of constitutively active AMPK (CA-AMPK) led to decreased caveolin-1 level. Consistently, administration of CA-AMPK in

LKB1
endo

-/-

mice lowered blood pressure with improved endothelial function
in vivo
.

Conclusions-
Our findings indicate that endothelial cell LKB1 plays an essential role in regulating eNOS activity, endothelial function, and blood pressure through modulating AMPK-mediated caveolin-1expression.
Abstract 52: Human Grk4γ142v, Via Histone Deacetylase 1, Produces At1r-dependent Hypertension
Authors: Jose Pedro , Wang Zheng , Sanada Hironobu , Yoneda Minoru , Zheng Chnuyu , Williams Scott , Bartlett Jacqueline , White Marquitta , Gordon Lindsay , Liu Monica , Konkalmatt Prasad , Wang Xiaoyan , Asico Laureano , Villar Van Anthony , Jones John , Armando Ines , Felder Robin , Eisner Gilbert
Published: March 2022

Human gene variants account for only a small proportion of essential hypertension in humans and have not been shown to produce hypertension in transgenic mice. The association between hypertension and 11 allelic variants of 8 candidate genes in humans (n=1074) was studied. We also evaluated the response to angiotensin receptor blockers (ARBs) in humans (n=681) and transgenic mice generated to express the human wild-type G protein-coupled receptor kinase 4γ (
hGRK4

γ
WT

) or the 142V allele

(hGRK4γ
142V

).
hGRK4
γ
variants (
R65L
,
A142V
, and
A486V
) were associated with essential hypertension;

hGRK4γ
142V

, by itself, predicted the hypertensive phenotype (60% accuracy);

hGRK4γ
142V

also interacted with
GNB3
and
PAI-1
. Human hypertensive carriers of
hGRK4

γ
142V

(n=68) had a greater decrease in systolic blood pressure (SBP mm Hg, 19.36, vs. 14.58, P=0.001) in response to ARBs than non-carrier (n=135) hypertensives.

hGRK4γ
WT

transgenic mice (anesthetized, n=42; conscious [n=12, day=118±0.8, night=131±1]) were normotensive while

hGRK4γ
142V

mice (anesthetized, n=54;conscious [n=12, day=128±2, night=148±3]) had hypertension, increased renal AT
1
R expression due to decreased histone deacetylase 1 (HDAC1) activity, a greater pressor response to angiotensin II (1000 ng/kg/minX30’)(n=6-9/group, WT=Δ+14±4%, 142V=Δ+26±3%), and a greater fall in SBP with candesartan (2mg/kg/dayX4d) (n=7/group, WT=Δ-5±2%,142V=Δ-29±3%); deletion of
Agtr1a
normalized the high BP of

hGRK4γ
142V

mice (n=5-13/group). To determine the role of renal HDAC1 on BP,
HDAC1
was silenced with HDAC-siRNA. Renal-specific HDAC1, but not HDAC2, silencing increased SBP (HDAC1-siRNA=112±5; mock=91±2; P<0.004, n=5/group). The BP response to ARBs was greater in HDAC1-siRNA- than mock-treated mice. These studies show that

hGRK4γ
142V

is associated with human essential hypertension, produces AT
1
R-sensitive hypertension in

hGRK4γ
142V

transgenic mice, and predicts a greater decrease in BP in response to ARBs in humans with essential hypertension and

hGRK4γ
142V

transgenic mice. This is the first demonstration of a concordance between rodents and humans for genetics, signaling pathway, and pharmacogenetics of essential hypertension.
Abstract 520: Fine Mapping of Two Loci Within a Major Albuminuria QTL on Rat Chromosome 6 That Affect Both Albuminuria and Deficient Nephron Development in The Munich Wistar Frömter Rat
Authors: Schulz Angela , Herlan Laura , Schmidbauer Martina , Kreutz Reinhold
Published: March 2022

We previously confirmed in the Munich Wistar Frömter (MWF) rat a functional role of a major quantitative trait locus (QTL) on rat chromosome (RNO)6 for both albuminuria development and an inherited nephron deficit in the consomic strain MWF-6SHR. We addressed the question whether an inherited nephron deficit is linked to the genetic basis of albuminuria and whether common genetic factors are responsible for both phenotypes in this rat model.

We generated congenic lines to dissect the RNO6-QTL using SHR rats with low albuminuria as a reference strain. Chromosomal fine mapping was performed by breeding of subcongenic lines, comparative genome analysis and physical mapping. The nephron number was determined by determination of the glomerular density in animals at 4 weeks of age; this method was validated by comparison with the absolute nephron numbers as determined by the physical fractionator method in parental strains.

Phenotyping of the congenic lines covering the RNO6-QTL demonstrated that both the albuminuria and the nephron locus were subdivided into at least two different colocalized informative loci. One interval defined by the congenic lines MWF.SHR-(D6Rat1-D6Rat81) and MWF.SHR-(D6Rat1-D6Rat117) covers 2.1 Mb and contains 26 known genes. Exchange of this locus had a strong impact on albuminuria at 8 weeks of age resulting in a decrease from 18.1 to 5.0 mg/24 h (p<0.0001) between the congenic strains and affected also the glomerular density (184 vs. 223 /mm
3
, p=0.0004). The second interval flanked by the congenic lines MWF.SHR-(D6Rat1-D6Rat117) and MWF.SHR-(D6Rat1-D6Mgh4) encompasses 2.8 Mb and contains 49 known genes. This interval influenced also albuminuria (decrease from 5.0 to 1.5 mg/24h, p=0.0001) and glomerular density (223 vs. 243 /mm
3
, p=0.008). These findings support the genetic link between albuminuria and nephron deficit in this model and provide the basis for further functional and comparative genomic analysis to obtain new insights into this association.
Abstract 528: Response of Muscle Sympathetic Nerve Activity to Heat Stress is Attenuated in Chronic Heart Failure
Authors: Cui Jian , Boehmer John P , Blaha Cheryl , Sinoway Lawrence I
Published: March 2022

Cutaneous vascular conductance (CVC) rises during heat stress in normal humans. Recently, we showed that this response is attenuated in chronic heart failure (CHF), even though the skin sympathetic nerve activity response to heat stress was not attenuated. Of note, heat stress evokes significant increases in muscle sympathetic nerve activity (MSNA) in healthy individuals. This effect may allow flow to be distributed to other tissues. The MSNA response to heat stress in CHF has not been reported. We postulated that in CHF the MSNA response to heat stress is attenuated. Passive whole body heating was applied with water-perfused suits on 9 male (60 ± 3 yrs) patients with stable class II-III CHF and 9 age-matched male healthy subjects. Whole body heating induced similar increases in skin temperature (~4 °C), internal temperature (~0.6 °C), similar reduction in blood pressure, and similar increase in heart rate. The elevation in forearm CVC in CHF patients was significantly lower than that in healthy control subjects (102 ± 29 vs. 312 ± 54 units,
P
< 0.001). While baseline MSNA in CHF was higher than in controls (
P
< 0.05); heat stress increased MSNA in the controls (33.2 ± 3.8 to 47.3 ± 4.4 bursts/min; 618 ± 74 to 934 ± 93 units/min, both
P
< 0.001, N = 9), but not in CHF (43.4 ± 5.7 to 49.6 ± 7.0 bursts/min; 996 ± 104 to 1039 ± 108 units/min, both
P
> 0.15, N = 6; two-factor ANOVA with repeated measure on one factor). Moreover, the MSNA change by heating in CHF was significantly lower than that in the controls (6.2 ± 2.6 to 14.1 ± 1.5 bursts/min; 43 ± 45 to 316 ± 34 units/min; both
P
< 0.01, unpaired t-test). The attenuated MSNA response to heating was not due to a ceiling effect as that static fatiguing handgrip in CHF in a control trial evoked significant increases in MSNA. These data show that the MSNA response to heat stress is attenuated in CHF patients. We postulate that the attenuated MSNA response contributes to an impaired re-distribution of blood low to the skin during heat stress in CHF.
Abstract 530: Renal Vasoconstriction is Augmented during Exercise in Peripheral Arterial Disease Patients: Contributions of Muscle Mechanoreflex and Oxidative Stress
Authors: Drew Rachel C , Muller Matthew D , Blaha Cheryl A , Mast Jessica L , Estep Lauren E , Cui Jian , Reed Amy B , Sinoway Lawrence I
Published: March 2022

Peripheral arterial disease (PAD) patients have augmented blood pressure increases during exercise. It is unknown whether PAD patients have greater renal vasoconstriction during exercise and how much the muscle mechanoreflex or oxidative stress contribute to this response. Eleven PAD patients and 10 healthy controls (CON) performed 4 minutes of mild, rhythmic, plantarflexion exercise of increasing intensity (0.5-2kg) with each leg (most and least affected legs for PAD). Eight PAD patients also performed exercise with their most affected leg during intravenous, high-dose, ascorbic acid (AA) infusion. Renal blood flow velocity (RBFV; Doppler ultrasound), mean arterial blood pressure (MAP; Finometer), and heart rate (HR; ECG) were measured. Renal vascular resistance (RVR), an index of renal vasoconstriction, was calculated as MAP/RBFV. Statistical analysis involved repeated measures ANOVA and paired samples
t
-tests. Baseline RVR and MAP were similar while HR was higher in PAD compared to CON (RVR: 2.08±0.23 vs. 1.87±0.20 arbitrary units, MAP: 94±3 vs. 93±3 mmHg, and HR: 72±3 vs. 59±3 b.min
-1
(p<0.05) for PAD and CON, respectively). PAD had greater RVR increases from baseline during exercise with both the most and least affected legs compared to CON, specifically during the first minute of exercise (PAD most: 2.08±0.23 to 2.60±0.29 (+26±5%) and PAD least: 1.96±0.24 to 2.22±0.25 (+17±5%) vs. CON: 1.87±0.20 to 1.91±0.20 (+3±3%) for the first minute of exercise, both
p
<0.05). AA infusion did not alter baseline RVR, MAP or HR. AA attenuated the augmented RVR increase in PAD during the first minute of exercise with the most affected leg (PAD most without AA: 2.10±0.31 to 2.78±0.38 (+33±2%) vs. PAD most with AA: 1.88±0.26 to 2.23±0.26 (+21±2%) for the first minute of exercise,
p
<0.05). In conclusion, these findings suggest that PAD patients have augmented renal vasoconstriction during exercise, with the muscle mechanoreflex and oxidative stress contributing to this increased response.
Abstract 531: Splanchnic Venous Compression With an Automated Binder is as Effective as Midodrine in the Treatment of Orthostatic Hypotension
Authors: Okamoto Luis E , Diedrich Andre , Baudenbacher Franz , Harder Rene , Whitfield Jonathan S , Gamboa Alfredo , Shibao Cyndya , Black Bonnie K , Raj Satish R , Robertson David , Biaggioni Italo
Published: March 2022

Treatment of orthostatic hypotension (OH) with pressor agents can worsen supine hypertension, cause drug interactions, or may be contraindicated in patients with cardiovascular disease. Splanchnic venous compression can improve OH but compliance and efficacy are limited with available garments. We developed an automated inflatable abdominal binder that provides servo-controlled compression (40 mm Hg) only on standing. To compare this device to standard of care with the α-1 agonist midodrine we studied ten autonomic failure patients (5 men, 68±2 yrs) who received placebo, their regular midodrine dose (2.5-10 mg), placebo combined with binder and midodrine combined with binder on separate days, in a randomized, single-blind, crossover study. Systolic blood pressure (SBP) was measured with patients seated and standing before and 1 hr postdrug. Midodrine alone and midodrine with the binder deflated increased seated SBP compared to placebo (29±7 and 25±7 vs. 3±6 mmHg at 1 hr, respectively, Figure A, p<0.01 for midodrine). The deflated binder did not increase seated SBP compared to placebo (6±6 mmHg, P=0.771). On standing, midodrine alone and abdominal compression combined with placebo had a similar improvement in orthostatic tolerance (AUCSBP, 253±36 and 238±42 vs. 27±43 mmHg*min for placebo, Figure B). The combination of binder with midodrine produced a greater pressor effect but the difference did not reach significance (359±97 mmHg*min, P=0.06). In conclusion, the automated inflatable abdominal binder is as effective as midodrine, the standard of care, in the management of OH, without increasing seated BP. Combining both therapies may produce an additive response.
Abstract 534: Increased in vivo Sympathetic Tone in Femoral Arteries of MLCK Biosensor Mice Exposed to Chronic Intermittent Hypoxia
Authors: Wang Youhua , Chen Ling , Zhang Jin
Published: March 2022

Increased sympathetic nerve activity (SNA) has been implicated in hypertension induced by chronic exposure to intermittent hypoxia (CIH) in both human and rodents. We have previously reported that the basal femoral arterial tone
in vivo
was primarily mediated by α1-adrenergic SNA, and hence was useful for assessing SNA in living animals in disease models, such as hypertension. While SNA hyperactivity is believed to be region specific in certain types of hypertension, such as that induced by angiotensin II plus salt, the aim of this study is to determine whether sympathetic tone is increased in femoral arteries in CIH-induced hypertension and to characterize vascular reactivity in CIH animals. Mice with smooth muscle-specific FRET-based Ca/calmodulin sensitive myosin light chain kinase biosensor were exposed to CIH (5% nadir O
2
for 1 min, followed by 21% O
2
for 1 min) or sham exposure (21% O
2
constantly) 8 hrs/day for 5 weeks. At the end of the exposure, blood pressure, measured with an intra-carotid artery catheter (1.5% isoflurane), was greatly increased in CIH group (91 ± 4 mm Hg, n = 8, vs. 83 ± 2 mm Hg in sham control, n = 6, P < 0.05). Mid-thigh femoral arteries were slightly dissected and superfused with physiological saline solution. Simultaneous arterial diameter and quantitative cytoplasmic [Ca
2+
] in smooth muscle cells within intact arteries were measured with Intra-Vital FRET microscopy. Under resting condition, femoral arteries from CIH-treated mice exhibited significantly increased basal tone (38 ± 4% vs 29 ± 4% of PD in control group, n = 5/group) and [Ca
2+
] (280 ± 27 vs 205 ± 27 nM). Local application, to the exposed portion of arteries, of phentolamine (0.01-3 μM) and prazosin (1 μM), caused more relaxation and [Ca
2+
] reduction in CIH than in handled control group. Dose-dependent vasoconstriction induced by phenylephrine, however, was similar, suggesting that the expression or sensitivity of the adrenoceptor was not altered. Passive outer diameter, an indicator of arterial remodeling, measured in Ca
2+
-free solution, were not different between control and CIH groups. These results indicate that the increased femoral arterial tone
in vivo
was also neurogenic, primarily due to hyper-(central) SNA in mice that developed hypertension following CIH.
Abstract 539: Reduced Firing Activity of Afferent Renal Innervation in the 2kidney/1clip Model of Hypertension
Authors: Freisinger Wolfgang , Karl Annalena , Ditting Tilmann , Heinlein Sonja , Ott Christian , Hilgers Karl Friedrich , Schmieder Roland E , Linz Peter , Schatz Johannes , Veelken Roland
Published: March 2022

Introduction:
Renal denervation has been shown to be effective in patients with hypertension. Recently, we found that afferent renal neurons show a distinctive feature, exhibiting predominantly a sustained firing upon current injection due to a specific expression of TTX resistant Na-channels. So far, the activity of these specific sensory neurons in hypertension is unclear. Hence we wanted to test the hypothesis that the firing pattern of renal afferent neurons is altered in the 2K/1C model of hypertension.

Methods:
Hypertension was induced by unilateral clipping of the renal artery in Sprague Dawley rats 3 weeks prior to experiments. Blood pressure was confirmed by an intraarterial measurement. Retrograde labelling (DiI) allowed the identification of renal afferent neurons in the Dorsal root ganglion (DRG Th11-L2). Current clamp was used to characterize neurons as “tonic”, i.e. sustained action potential (AP) firing or “phasic”, i.e. <5 APs according to their firing upon current injections. Electrophysiological parameters and AP properties were determined in neurons of hypertensive animals and controls. Renal morphology was investigated.

Results:
Renal DRG neurons of hypertensive animals (n=88) showed a significant decrease in tonic firing pattern compared to controls (n=84) (44.3% [39/88] vs. 59.5% [50/84], p< 0.05). Current Clamp analysis revealed no significant change in action potential shape in hypertensive animals (overshoot, firing threshold, AP- duration). Tonic cells revealed a higher capacity in hypertensive rats (124pF vs. 87.8pF, p<0.01), all other parameters (resting potential, resistances) were equal in both groups. No differences in renal pathomorphology could be observed between clipped and non-clipped kidney in hypertensive animals. (BP: 187.5 mmHg versus controls: 106.5mmHg)

Conclusion:
Hence the excitability of afferent renal neurons in a model of renovascular hypertension is significantly altered, as renal afferent DRG neurons exhibit less sustained firing upon stimulation. Sustained high blood pressure is possibly rather characterized by a generally decreased afferent renal activity with impaired sympathoinhibition than by activated sympathoexcitatory fibers from the clipped kidney.
Abstract 554: Gastrin and D
1
Dopamine Receptor Interact to Induce Natriuresis and Diuresis
Authors: Chen Yue , Zheng Shuo , Zeng Chunyu
Published: March 2022

Oral NaCl produces a greater natriuresis and diuresis as compared with an intravenous infusion of the same amount of NaCl, indicating the existence of a gastro-renal axis. Gastrin is the major gastrointestinal hormone, which could be taken up by the renal proximal tubule (RPT) cells. We hypothesized that gastrin and dopamine receptors in the kidney interact to synergistically increase sodium excretion, an impaired interaction may be involved in the pathogenesis of hypertension. In Wistar-Kyoto (WKY) rats, infusion of gastrin induced a natriuresis and diuresis, which was abrogated in the presence of CI-988, a gastrin receptor (CCK
B
R) antagonist, as well as SCH 23390, a D
1
-like receptor antagonist. Similarly, the natriuretic and diuretic effect of fenoldopam, a D
1
-like receptor agonist, was blocked by
SCH23390
, as well as CI-988. However, the natriuretic effects of gastrin and fenoldopam were not observed in spontaneously hypertensive rats (SHRs). The gastrin/D
1
-like receptor interaction was also confirmed in RPT cells. In RPT cells from WKY but not SHRs, stimulation of either D
1
-like receptor or gastrin receptor inhibited Na
+
-K
+
-ATPase activity, an effect that was blocked by the presence of
SCH23390
or CI-988. In RPT cells from WKY and SHRs, CCK
B
R and D
1
R co-immunoprecipitated, which were increased after stimulation of either D
1
R or CCK
B
R receptor in WKY cells, but not in SHR cells. Stimulation of one receptor increased RPT cell membrane expression of another receptor. The data suggest that there is a synergism between CCK
B
R and D
1
-like receptor to increase sodium excretion. Aberrant interaction between the renal CCK
B
R and D
1
-like receptors (e.g., D
1
R) may play a role in the pathogenesis of hypertension.
Abstract 560: Vitamin D Depletion Aggravates Hypertension in Transgenic Rats
Authors: Andersen Louise B , Przybyl Lukasz , Herse Florian , Christesen Henrik T , Szijártó István , Gollasch Maik , Dechend Ralf , Müller Dominik N
Published: March 2022

Introduction:
Vitamin D may ameliorate hypertension and kidney disease through genomic and extra-genomic pathways. Several studies have shown that vitamin D levels can affect levels of circulating FoxP3-positive regulatory T-lymphocytes. Previously, our group has demonstrated that adoptive transfer of FoxP3-positive T-lymphocytes ameliorated the phenotype in a mouse model of angiotensin-II induced cardiac damage.

Objective:
To investigate the impact of vitamin D depletion in a transgenic rat model of angiotensin II-mediated hypertensive organ failure, and to investigate the possible association with levels of FoxP3 regulatory T-lymphocytes.

Methods:
In 4-week old age-matched rats overexpressing the human renin and angiotensinogen genes, group 1 (n=18) received vitamin D depleted chow, and group 2, (n=15) received chow with standard contents of vitamin D. Blood pressure (tail cuff) and 24-hour albuminuria were determined once weekly. After three weeks, animals were sacrificed. Heart tissue was examined for atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) by RT-PCR. Lymphocytes from spleens were isolated, and the percentage of CD4+ cells, which were CD4+CD25+FoxP3-positive, was measured by flow cytometry. Mesenteric arteries were removed and stimulated with nitroprusside and acetylcholine to investigate the relaxation potential of the epithelium.

Results:
The vitamin D depleted group had higher blood pressure at all times (mean differences were 23.40 mmHg, 14.31 mmHg and 15.71 mmHg respectively, p<0.05), higher heart-to-body weight ratio, and higher ANP and BNP levels. No differences were found between groups in mortality or proteinuria. Neither the levels of CD4+CD25+FoxP3-positive cells in spleen, nor the relaxation potential measured in mesenteric arteries differed between groups.

Conclusion:
Short-term vitamin D depletion aggravated hypertension and end-organ damage in a rat model of angiotensin II-induced hypertension. However, the aggravated phenotype was not due to different levels of splenic FoxP3-positive activated T-lymphocytes or to higher endothelial resistance in arteries.
Abstract 562: Differential Effects of Renin Inhibitors and Ca2+ Channel Blockers on Blood Pressure and Vascular Function in Caveolin-1 Null Mice
Authors: Pojoga Luminita , Opsasnick Lauren A , Siddiqui Waleed T , Reslan Ossama M , Adler Gail K , Williams Gordon H , Khalil Raouf A
Published: March 2022

Caveolin-1 (cav-1) is a transmembrane protein identified in plasma membrane caveolae, and a potential modulator of renal and vascular function and insulin sensitivity. We have shown that cav-1 gene variants are associated with insulin resistance (IR) in hypertensive humans, and that cav-1 deficiency in mice leads to increased blood pressure (BP) and IR. To test whether these changes in the cav-1 KO involve renal or vascular abnormalities, we treated WT and cav-1 KO mice for 14 days with placebo, the renin inhibitor aliskiren (50 mg/kg/day), or the Ca
2+
channel blocker amlodipine (6 mg/kg/day) and assessed BP, fasting blood glucose, HOMA-IR, plasma aldosterone (ALDO), and vascular function.

Cav-1 KO mice, as compared with WT, showed increased BP (131±7 vs. 110±2 mm Hg), blood glucose (112±4 vs. 83±4 mg/dl), HOMA-IR (1.9±1.1 vs. 1.1±0.4), lower plasma ALDO (97±10 vs. 131±42 ng/dl), and altered vascular reactivity--reduced Phe-induced vasoconstriction (0.6±0.2 vs. 1.1±0.2g), enhanced acetylcholine (ACh)-induced relaxation (65±11 vs 23±7%), and enhanced relaxation in response to exogenous NO. Endothelium removal, NOS inhibition, or guanylate cyclase inhibition abolished ACh-induced relaxation, suggesting changes in endothelium-dependent NO-cGMP pathway in cav-1 KO mice. In cav-1 KO mice aliskiren significantly reduced BP to 113±4 mm Hg, ALDO levels by 40%, and HOMA-IR to 0.9±0.1, but had no significant effects on blood glucose, Phe-induced vasoconstriction, ACh- or exogenous NO-induced vasorelaxation. In contrast, amlodipine reduced BP to 117±4 mmHg (this effect did not reach significance), had no effect on ALDO levels, and showed a trend for increased IR. Importantly, amlodipine enhanced the sensitivity to Phe in both WT and cav-1 KO, and reduced the ACh-induced relaxation in cav-1 KO mice to 47±11%.

Thus aliskiren treatment in cav-1 KO mice reduced BP possibly through suppression of RAAS and improved insulin sensitivity, but did not affect vascular function. In contrast, amlodipine treatment showed small changes in BP and IR but had adverse effects on vascular reactivity in cav-1 KO mice, raising the concern that it could have similar adverse effects on vascular function in hypertensive individuals that carry the cav-1 minor allele gene variants.
Abstract 618: Inflammatory Biomarkers are Improved Subsequent to an Aerobic Exercise Training Intervention in African Americans
Authors: Babbitt Dianne M , Diaz Keith M , Feairheller Deborah L , Sturgeon Kathleen M , Perkins Amanda M , Veerabhadrappa Praveen , Williamson Sheara T , Kretzschmar Jan , Ling Chenyi , Lee Hojun , Grimm Heather , Brown Michael D
Published: March 2022

African Americans (AA) have the highest prevalence of hypertension (HTN) in the world which may emanate from their predisposition to heightened endothelial inflammation. Long-term exposure of the endothelium to proinflammatory cytokines leads to increased oxidative stress, inflammation, and endothelial dysfunction which support an environment favoring HTN. It is thought that the balance between pro- and anti-inflammation plays a crucial role as a determinant of endothelial homeostasis and health. Positive associations between proinflammatory markers such as C-reactive protein (CRP) and interleukin-6 (IL-6) with HTN have been reported. Elevated circulating levels of the anti-inflammatory cytokine, interleukin-10 (IL-10) have been associated with improved endothelial function. In addition, aerobic exercise training (AEXT) has been associated with favorable endothelial adaptations.

PURPOSE:
To evaluate the effect of a 6-month AEXT intervention on the inflammatory biomarkers CRP, IL-6, and IL-10 in African Americans. A secondary purpose was to determine whether there are relationships between the changes in CRP, IL-6, and IL-10 subsequent to the 6-month AEXT intervention.

METHODS:
A Pre-Post design was employed following the completion of screening, dietary stabilization, and antihypertensive medication tapering. Subjects were sedentary, putatively healthy, 45-71 y/o AA men and women. Baseline evaluation included fasting blood sampling and graded exercise testing (GXT). Participants engaged in 6-months of AEXT. At the conclusion of the AEXT intervention, baseline tests were repeated. Concentrations of CRP, IL-6, and IL-10 were determined using an ELISA.

RESULTS:
There was a significant decrease in CRP (n=37; p=0.01) and a significant decrease in IL-6 (n=32; p=0.04) following AEXT. IL-10 was increased following the AEXT intervention, however it was not statistically significant (n=26; p=0.08). There were no significant relationships between the changes in the inflammatory biomarkers measured.

CONCLUSION:
Based on the favorable adaptations in the inflammatory biomarkers CRP and IL-6, AEXT may be a viable, nonpharmacologic method to reduce the risk for HTN in AA by improving inflammation status and endothelial function.
Abstract 621: Obesity Leads To Activation Of Circulating T Lymphocytes In Female, Not Male, African American Teenagers
Authors: De Miguel Carmen , Xu Xiaojing , Wang Xiaoling , Ownby Dennis , Pollock Jennifer S
Published: March 2022

Obesity and cardiovascular diseases are prominent in the African American population. The immune system is key in the development of these diseases, and clinical evidence indicates that individuals that progress to cardiovascular disease display inflammatory markers years before the disease is openly declared. We hypothesized that obesity would lead to alterations of the circulating T lymphocyte profile and activation status in a population of African American teenagers. Lean (BMI < 50th percentile) and obese (BMI ≥ 95th percentile) African American teenagers (14-20 years-old; n=13-22/group) of both genders were recruited from public schools of Augusta, GA. Circulating immune cell phenotypes and activation status were analyzed by fluorescence-activated cell sorting (FACS), and total whole blood cell counts with 5 differentials (neutrophils, lymphocyte, monocyte, eosinophils and basophils) were also determined. Results are expressed as absolute numbers ± SD (x 105 cells/ml). When compared to lean counterparts, obese individuals presented significantly elevated numbers of circulating T lymphocytes (CD3+ cells (x 105 cells/ml): 174.6±65 vs. 148.3±53.1), T helper cells (CD4+ cells (x 105 cells/ml): 170.7±60.6 vs. 144.3±47) and activated T lymphocytes (CD3+/CD69+ cells (x 105 cells/ml): 5.62±7.5 vs. 3.78±3.7). A sex stratified analysis of the data further indicated that obese males had significantly elevated numbers of circulating CD4+ cells (163±51 x 105 cells/ml) compared to lean males (136.4±47.0 x 105 cells/ml), while obese females presented elevated numbers of T lymphocytes (176.6±68.5 vs. 150.8±51 x 105 cells/ml), T helper cells (175±65 vs. 150.6±46.3 x 105 cells/ml) and activated T cells (CD3+/CD69+: 6.8±8.9 vs. 4.2±4.5 x 105 cells/ml) and T cytotoxic cells (CD8+/CD69+: 3.9±4.0 vs. 2.8±2.1 x 105 cells/ml) when compared to lean females. In conclusion, obesity in African American teenagers produces an imbalance in the circulating T cell profile, leading to an elevation in T lymphocyte numbers, and, specifically in female individuals, to the activation of T cells and T cytotoxic cells. The identification of this obesity-related T-cell activation may provide new etiologies and biomarkers for obesity-induced cardiovascular disease.
Abstract 624: Induction of Oxidative Stress in Dendritic Cells Promotes Isoketal Formation and Activation of T Cells
Authors: Loperena Roxana , Kirabo Annet , Roberts L. J , Harrison David G
Published: March 2022

We and others have previously shown that T cells play an important role in hypertension, but the mechanisms by which they are activated remains undefined. Dendritic cells present antigens and secrete cytokines that modify T cell polarization. The NADPH oxidase also contributes to hypertension via multiple mechanisms. We have found that dendritic cells (DCs) from ang II-infused mice have a 5-fold increase in superoxide production by NADPH oxidase. Superoxide catalyzes the formation of H2-isoprostanes, which rearrange to form reactive γ-ketoaldehydes termed isoketals that adduct to protein lysines which renders them immunogenic. We hypothesized that oxidative stress catalyzes the formation of isoketals which alters the function of dendritic cells leading to inflammation and hypertension. Thus, we exposed DCs from spleens of C57Bl/6 mice to tert-Butyl hydroperoxide (t-BHP) for 30 minutes. Using flow cytometry, we found that t-BHP exposure increased levels of isoketal-ligated proteins in the CD11b+/CD11c+ DCs population compared to control (19.6 ± 3.7 vs. 10.6 ± 2.5, respectively; P=0.035). Importantly, we found DCs exposed to t-BHP become capable of activating T cells. After exposure to this oxidant for 30 minutes, DCs were cultured with autologous T cells for 7 days and proliferation was monitored by carboxyfluorescein succinimidyl ester (CFSE) and flow cytometry. Exposure of DCs to t-BHP promoted a 4-fold increase in proliferation of autologous CD8+ T cells compared to controls. This was also associated with a modest proliferation of CD4+ T cells. Thus, hypertension promotes oxidative stress in DCs. Induction of oxidative stress in DCs leads to formation of highly reactive isoketals, which alters the function of endogenous proteins. Formation of isoketals in DCs leads to T cell and, in particular, CD8 activation. These findings provide a mechanism as to how T cells are activated in hypertension and provide insight into the inflammatory nature of this disease.
Abstract 630: Blood Pressure and Kidney Function in PRCP deficient Mice
Authors: Maier Christoph , Wysocki Jan , Ye Minghao , Haber Philipp K , Schmaier Alvin H , Batlle Daniel
Published: March 2022

Changes in the enzymes involved in Ang II degradation may influence disease conditions such as hypertension and kidney disease. The enzyme prolylcarboxypeptidase (PRCP) catalyzes the conversion of Ang II to Ang(1-7) and its deficiency results in a phenotype characterized by a prothrombotic state, hypertension, and impaired wound healing. Here, we investigated kidney function and blood pressure in young mice, 10-16 weeks of age, with a subtotal PRCP deficiency (PRCP genetrap, PRCPgt).

Enzyme activity based on a synthetic fluorogenic peptide was used to measure PRCP activity. The activity of recombinant PRCP was strongly pH-dependent with an optimum in the acidic range (pH 5). In keeping with this, recombinant PRCP degraded Ang II at pH 5, but not at pH 7.4 in-vitro. PRCP activity was detected in serum and in kidney of WT mice whereas PRCPgt/gt mice displayed highly diminished serum PRCP activity (about 5% of the WT).

Kidney function was assessed by urinary protein/creatinine ratio and GFR. At 10 weeks of age, neither female nor male PRCPgt/gt animals showed elevations in urinary protein/creatinine-ratio (female PRCPgt/gt 19.9±1.4 vs. WT 23.5±1.9 and male PRCPgt/gt 32.4±3.5 vs. WT 34.8±1.8). At 16 weeks of age, the GFR (measured by clearance of FITC-Inulin) was not different (female PRCPgt/gt 4.10±0.32 vs. WT 4.33±0.29 and male PRCPgt/gt 4.41±0.50 vs. WT 4.28±0.31 ul/min/g). Systolic blood pressure was significantly elevated in PRCPgt/gt animals as compared to the respective WT controls (female PRCPgt/gt 147.8±3.4 vs. WT 117.3±7.1 mmHg, male 138.1±8.4 vs. 120.5±3.6 mmHg, p<0.05).

PRCP deficient mice have normal GFR but elevated basal blood pressure. Whether PRCP deficiency causes hypertension as a result of impaired Ang II degradation or other mechanisms needs to be determined.
Abstract 635: The Pressure Natriuresis Response To A Physician Visit In A Pediatric Population
Authors: Mulloy Evan A , Hanevold Coral , Ortiz Luis , Nwobi Obioma , Harshfield Gregory A
Published: March 2022

Background:
Improper sodium handling during stress (i.e. sodium retention) increases the risk of cardiovascular events, such as hypertension. Efficient identification of these retainers,therefore, is important in clinical practice. We developed a protocol to identify these patients that can be implemented into Standard of Care.

Methods:
The protocol was tested using 19 patients (aged 10-19) in an outpatient clinic. Urine samples and blood pressure were obtained prior to and following a normal physician visit to establish baseline and stress values, respectively.

Results:
44% (8/19) of subjects were sodium retainers, retaining 3.2 mEq/hr, or approximately 73.5 mg of sodium with a systolic blood pressure (BP) increase of 5.4 mm Hg during the visit. 7/8 of these retainers were hypertensive. Excretors filtered 6.2 mEq/hr (141.6 mg) of sodium and showed a small decrease in systolic BP by 0.7 mm Hg.

Conclusions:
Our results indicate that the normal stress of a physician visit can induce pressure natriuresis in patients and that this protocol could serve as a clinically efficient method for identifying sodium retainers at increased risk for cardiovascular disease.
Abstract 65: Soluble Angiotensin Converting Enzyme 2 as an Additional Source of Blood Pressure Regulation within the Kidney
Authors: Ortiz Melo David I , Mattocks Natalie K , Xu Katherine , Griffiths Robert , Gurley Susan B
Published: March 2022

Angiotensin Converting Enzyme 2 (ACE2) is a transmembrane carboxypeptidase that degrades angiotensin II (AngII) to Ang(1-7). This membrane-bound enzyme can be cleaved by metalloproteinases such as ADAM17, releasing the catalytically active ectodomain to generate soluble ACE2. The objective of this study is to determine if soluble ACE2, acting locally in the kidney, could modulate the blood pressure (BP) response to AngII infusion.

In order to isolate the actions of ACE2 in the kidney from systemic tissues, we utilized kidney cross-transplantation. We studied male (129/SvEv x C57BL/6)F1 ACE2 knockout (KO) and wild-type (WT) mice. Kidney transplants were performed to generate 4 experimental groups: 1) WT, 2) kidney ACE2KO, 3) systemic ACE2KO, and 4) total ACE2KO. Mean arterial BPs (MAP) were measured with radiotelemetry at baseline and during a 2-week infusion of AngII (1ug/kg/min). Enzymatic activity was determined using an ACE2-specific quenched fluorescent substrate assay.

Total ACE2KO mice had an enhanced hypertensive response to AngII compared to WT mice (152±6 vs.144±7 mmHg; p=0.03), consistent with our previous findings of enhanced susceptibility to AngII hypertension in mice globally deficient in ACE2. The presence of ACE2 in either the kidney or systemic tissues restored MAPs to levels similar to the WT group (kidney ACE2KO 140±7mmHg, systemic ACE2 KO 140±5 mmHg, p<0.01 vs. total KO). Serum ACE2 activity levels were decreased in systemic KO mice (40±35 RFU/ul/hr) but unaffected in kidney KO mice, compared to WT (153±25 vs. 126±26 RFU/ul/hr, respectively). However, despite genetic deletion from all kidney cells, kidney ACE2KO mice had similar urinary ACE2 activity compared to systemic ACE2KO (76±32 and 108±52 RFU/ul/hr, p=NS). Urinary ACE2 activity in WT mice was highest, 217±36 RFU/ul/hr, compared to total KO which was undetectable (p<0.001).

Our studies demonstrate that restoration of ACE2 in either the kidney or systemic tissues is sufficient to abrogate the exaggerated hypertensive response to chronic AngII infusion. Soluble ACE2 delivered to the kidney may be an additional source of ACE2 to act within the kidney since the cells produce no ACE2 locally in kidney KO mice. Our studies highlight a possible role of soluble ACE2 in BP regulation.