bluuebunny/crossref_metadata_2025 huggingface dataset:
Nocturnal Urination May Determine Dipping Status: A 24 Hour Ambulatory Blood Pressure Study.
Authors: Bursztyn Michael , Mekler Judith
Published: July 2021

P128

Non-dipping,
i.e.
failure to reduce blood pressure (BP) by 10% or more, is considered an important prognostic variable of 24h ambulatory blood pressure monitoring (ABPM). However, some people wake up, rise and go to urinate at night. Usually, 24h ABPM derived means include these rises in the nighttime BP mean, by presenting total-day and total night (TDTN) levels. In 80 consecutive patients (33 females) age 63±10years, undergoing 24h ABPM who reported waking up to urinate at night we compared TDTN with actual day-awake and night-sleep (DANS) levels. Daytime awake BP, and nighttime awake BP were 141±15/83±11, and 140±18/82±12mmHg respectively p≥0.16. Nocturnal BP was 128±16/71±10mmHg by TDTN and 126±16/70±10mmHg by DANS p≤0.00001. The difference between TDTN and DANS calculations, increased from 1.2±0.9/1.0±0.8mmHg in those who woke once a night(n=51) to 1.8±1.4/1.7±1.3mmHg in those who woke more frequently(n=29) p≤0.02. Nocturnal decline of BP by TDTN was 13±11/11±7, and by DANS 15±12/13±7mmHg p≤0.0001. Although the absolute difference between TDTN and DANS was small, the effect on nocturnal dip was profound. Average systolic BP (SBP) dipping was 9.3±0.1% for TDTN, and 10.5±0.1% for DANS p≤0.0003, and that of diastolic BP (DBP), 13.5±0.1% and 15.6±0.1%, respectively p≤0.0001. The prevalence of SBP non-dipping decreased from 51.3% by TDTN, to 35% by DANS p≤0.038, and that of DBP from 36.3% to 21.3% respectively p≤0.036. The TDTN non-dipping status of waking once (n=51), twice (n=22), or thrice or more (n=7) at night was 45.1%, 54.5%, and 100% for SBP p≤0.024, and for DBP it was 27.5%, 45.5%, and 71.4%, respectively p≤0.044. By DANS the number of non-dippers decreased substantially, as compared with TDTN for each number of awakenings, 37.3%, 40.9%, and 85.6% for SBP p≥0.051, and 15.7%, 22.7%, and 57.1% for DBP, p≤0.042. Inclusion of awake BP measurements during the night obscures the normal dipping pattern of ABPM, in people who wake up to urinate. Non-dipping increases with number of awakenings, and leads to its substantial overestimation. Thus in 24h ABPM, as in anything else, taking into account people’s actual behavior increases accuracy of results.
Transfer of Brown Norway Rat Chromosome 13 into Dahl S Genomic Background Confers Protection from High Salt Diet
Authors: Cowley Allen W , Roman Richard J , Kaldunski Mary L , Tonellato Peter J , Dumas Pierre , Greene Andrew S , Jacob Howard J
Published: July 2021

P132

Consomic rats (SS
BN13
) were bred in which chromosome 13 from normotensive inbred Brown Norway (BN/Mcw) rats was introgressed into the background of Dahl salt-sensitive (SS/Mcw) rats. The present studies determined the mean arterial pressure (MAP) responses to salt; renal and peripheral vascular responses to norepinephrine (NE) and angiotensin II (AngII); and protein excretion and renal histology in rats that received a high salt (4% NaCl) for 3 weeks. Indwelling arterial catheters were implanted in the 2
nd
week of high salt and MAP was recorded for 3 days during the 3
rd
week of high salt, and again 36 hours after 10mg/kg Lasix and return to a low salt (0.4%) diet. Results: High salt MAP of SS/Mcw rats averaged 183+4 mmHg, SS
BN13
averaged 124+3 mmHg, and BN/Mcw averaged 132+4 mmHg. The reduction in MAP with sodium depletion averaged 31.8+3 mmHg in SS/Mcw rats but was significantly less in SS
BN13
rats (14.7+1.6 mmHg) and BN/Mcw rats (13.9+2 mmHg). Protein excretion of SS/Mcw rats on high salt averaged 270+31 mg/24hr compared to 55+22 mg/24hr in SS
BN13
rats, and 19+7 mg/24hr in BN/Mcw rats. Reduction of renal blood flow to iv administration of NE and AngII, was significantly greater SS/Mcw rats compared to SS
BN13
and BN/Mcw rats. Severe medullary interstitial fibrosis and tubular necrosis was consistently seen in SS/Mcw rat kidneys but not in the SS
BN13
or BN/Mcw rats following 3 weeks of high salt intake. These results demonstrate the power of functional mapping of complex traits using chromosomal transfer techniques and reveal a powerful gene (or set of genes) within BN/Mcw chromosome 13 that confers protection from the detrimental effects of a high salt diet to the Dahl salt-sensitive rat (SS/Mcw). It remains to be determined if the renoprotective effect is secondary to the reduction in blood pressure with chromosomal transfer, or a direct protective effect.
Enhanced [Ca
2+
]
I
and Contractility of Renal Arterial Smooth Muscle in a Rat Model of Hypertension Produced by Reduction of Uterine Perfusion Pressure in Late Pregnancy
Authors: Murphy Jason G , Herrington Jason N , Alexander Barbara T , Granger Joey P , Khalil Raouf A
Published: July 2021

P147

Reduction of uterine perfusion pressure during late pregnancy has been suggested to trigger increases in renal vascular resistance and pregnancy-induced hypertension; however, the cellular mechanisms involved are unclear. We investigated whether reduction of uterine perfusion pressure in late pregnancy is associated with increased [Ca
2+
]
i
and contractility of renal arterial smooth muscle. Single smooth muscle cells were isolated from renal interlobular arteries of late pregnant Sprague-Dawley rats and a hypertensive pregnant rat model produced by chronic reduction in uterine perfusion pressure (RUPP). The cells were loaded with fura-2 and cell length and [Ca
2+
]
i
were measured. In cells of pregnant rats incubated in Hank’s solution (1 mmol/L Ca
2+
), resting [Ca
2+
]
i
was 62±3 nmol/L and cell length was 69±3 μm. In RUPP rats, resting [Ca
2+
]
i
(101±3 nmol/L) was significantly greater and cell length (53±2 μm) was shorter than pregnant rats. In pregnant rats, angiotensin II (AII, 10
-7
mol/L) caused transient increase in [Ca
2+
]
i
to 412±25 nmol/L followed by a maintained increase to 158±15 nmol/L, and 23±2% cell contraction. In RUPP rats, the AII-induced [Ca
2+
]
i
transient (434±22 nmol/L) was not significantly different from pregnant rats, but the maintained [Ca
2+
]
i
was significantly elevated to 198±7 nmol/L and cell contraction was increased to 33±3%. In pregnant rats, the Ca
2+
channel agonist Bay K8644 (1 μmol/L) caused maintained increase in [Ca
2+
]
i
to 292±12 nmol/L and 31% contraction that were significantly enhanced in RUPP rats. In Ca
2+
-free (2 mmol/L EGTA) Hank’s, AII- and caffeine (10 mmol/L)-induced [Ca
2+
]
i
transient and cell contraction were not significantly different between pregnant and RUPP rats suggesting no difference in Ca
2+
release from intracellular stores. The enhanced basal, maintained AII- and Bay K8644-induced [Ca
2+
]
i
and cell contractility in RUPP rats suggest enhanced Ca
2+
entry mechanisms of smooth muscle contraction in resistance renal arteries and may, in part, explain the increased renal vascular resistance associated with pregnancy-induced hypertension.
Modulation of Platelet Aggregation by the Ep
3
Receptor for Prostaglandin E
2
Authors: Athirakul Krairerk , Thomas Dennis W , Fabre Jean-Etienne , Koller Beverly , Coffman Thomas M
Published: July 2021

P153

Prostaglandins (PGs) are vasoactive eicosanoids that regulate vascular tone and platelet functions. PGE
2
is produced by activated platelets and is known to have dual effects on platelet function. At high concentrations, PGE
2
inhibits platelet aggregation while at lower concentrations, PGE
2
may potentiate aggregation. The physiologic functions of PGE
2
are mediated through binding to specific PGE
2
receptors (EPs). Four EP receptor isoforms (EP1-4) have been identified, each with distinctive tissue distributions and signaling mechanisms. However, roles for the individual EP receptor isoforms in regulating platelet functions are not clearly defined. In some cell types, the EP
3
receptor couples to the inhibitory protein Gi, resulting in reduced intra-cellular cAMP levels. As reduced cAMP levels enhance platelet aggreation, we hypothesized that the EP3 receptor might mediate the pro-aggregatory actions of PGE
2
. To address this issue, we studied mice with targeted disruption of EP
3
receptor gene (EP
3
-/-
). Bleeding times in EP
3
-/-
mice were similar to wild type controls (70±18 sec vs. 84±18 sec, p=0.57). To study the effects of EP
3
receptor on platelet function in vitro, platelet aggregation was determined by light absorbance. PGE
2
at a dose of 10 nM had no significant effect on platelet aggregation in either EP
3
-/-
or wild type mice. However, in platelets from wild-type mice, the combination of 10 nM PGE
2
and 500 nM of thromboxane receptor (TP) agonist U46619 caused vigorous aggregation (75±3.5%). In contrast, 10 nM of PGE
2
with 500 nM TP agonist had no effect on EP
3
-deficient platelets (4.3±2.8%, p<0.01 vs wild-type). These studies identify actions of the EP
3
receptor to promote platelet aggregation.
Effects of Sphingosylphosphorylcholine on Vascular Smooth Muscle Cell Growth and on the Delayed Growth Response Cell Cycle Proteins Cdk2 and Cdc2
Authors: Sachinidis Agapios , Hegele Eva , Claudia Seul , Eberhardt Georg , Seewald Stefan , Ko Yon , Vetter Hans
Published: July 2021

P160

Abnormal vascular smooth muscle cell (VSMC) proliferation plays an important pathophysiological role in the development of vascular disease. We examined the effect of Sphingosylphosphorylcholine (SPC) on DNA synthesis ([
3
H]thymidine-incorporation method), cell number, cell volume, and cell diameter (CASY-1 coulter counter) as well as on the delayed response cell cycle proteins cyclin-dependent kinase2 (Cdk2) and Cdc2 (a serine/threonineprotein kinase) after stimulation of quiescent VSMCs with 5 μg/mL SPC for 2, 4, 6, 8, 12, 14, 16, 18, 20, 24, and 36 h. Cdk2 protein level is reduced when cells are in the G0-phase and its level is increased by the progression from G1- to S-phase upon addition of growth factors. Progression of the cells from the G2-phase (high level of tyrosine15-phosphorylated form of Cdc2) into M-phase is regulated by dephosphorylation of the Tyr15 residue of Cdc2 (34 kDa). Cdc2 phosphorylation status at Tyr15 and Cdk2 protein level were examined by chemiluminescence western blotting analysis using primary antibodies which recognizes Tyr15-phosphorylated Cdc2 and Cdk2 protein, respectively. Stimulation of VSMCs for 12, 14, 16, 18, 20, 24, and 32 h caused a 50±6, 50±11, 143±3, 192±15, 304±32, 221±29 and 245±26% increase in [
3
H]thymidine incorporation. Stimulation of VSMCs with SPC for 24, and 32 hour resulted in an 8 and 32% increase in cell number. Cell volume and radius was increased by 40 and 11%, respectively. Stimulation of quiescent VSMCs with SPC for 12, 16, 20, 24 and 32 h caused an 7, 51, 50, 76, and 32% increase of Cdk2 level. After stimulation of VSMCs for 20 and 24 h a 91 and 103% increase of Tyr15-phosphorylation, respectively, occurred. An almost complete Tyr15-dephoshorylation occurred after 32 h. We might conclude that SPC is a potent mitogenic and hyperthrophic factor for VSMCs acting through stimulation of Cdk2 and Cdc2.
Convergence of Multiple Protein Kinase Pathways of Angiotensin II Type 1 Receptor on cAMP Response Element-Binding Protein (CREB) in Rat Vascular Smooth Muscle Cells
Authors: Ichiki Toshihiro , Funakoshi Yuko , Takeda Kotaro , Takeshita Akira
Published: July 2021

P163

We previously reported a critical role of cyclic AMP response element (CRE) of interleukin-6 gene promoter in the induction of interleukin-6 gene expression by angiotensin II (AngII). We examined signaling pathways that are responsible for AngII-induced phosphorylation of CRE binding protein (CREB) at serine 133 that is a critical marker for the activation in rat vascular smooth muscle cells (VSMC). We performed Western blot analysis using an antibody against the phosphorylated form of CREB. AngII time-dependently induced phosphorylation of CREB with a peak at 5 minutes. The phosphorylation was dose-dependent. The AngII-induced phosphorylation of CREB was blocked by CV11974, an AngII type I receptor (AT1-R) antagonist but not by PD123319, an antagonist of Ang II type 2 receptor, suggesting that AT1-R mediates the phosphorylation of CREB. Inhibition of extracellular signal-regulated protein kinase (ERK) by PD98059 or inhibition of p38 mitogen activated protein kinase (MAPK) by SB203580 partially inhibited AngII-induced CREB phosphorylation. A protein kinase A (PKA) inhibitor, H89, also partially suppressed AngII-induced CREB phosphorylation. However, inhibition of calmodulin dependent kinase II or phosphatydilinositol 3 kinase did not affect Ang II-induced CREB phosphorylation. Transcriptional activation as measured by a CRE/luciferase reporter was increased by 1.7-fold by AngII stimulation. Infection of adenovirus vector expressing dominant negative form of CREB, which the serine residue at 133 is replaced with alanine to VSMC partially suppressed Ang II-induced thymidine incorporation. These findings suggest that AngII activates multiple protein kinase pathways involving two MAPK pathways and PKA, all of which contribute to the activation of CREB. And CREB-dependent gene transcription plays an important role for Ang II-induced mitogenesis. Activation of CREB-dependent gene transcription may play important roles in cardiovascular remodeling process.
Dexamethasone Inhibits Nf-κB, P22phox, and Protects Against Angiotensin Ii-Induced Renal Damage
Authors: Muller Dominik N , Dechend Ralf , Hampich Franziska , Park Joon-Keun , Fiebeler Anette , Schmidt Folke , Theuer Jurgen , Bieringer Markus , Mervaala Eero Ma , Ganten Detlev , Haller Hermann , Luft Friedrich C
Published: July 2021

P167

We recently reported that NF-κB activation promotes inflammation in rats harboring both human renin and angiotensinogen genes (dTGR). We now tested the hypothesis that dexamethasone (DEX) inhibits NF-κB and ameliorates renal and cardiac end-organ damage. The dTGR feature moderate hypertension, severe renal, and cardiac damage, as well as over 50% mortality at 7 weeks. Immunohistochemical analysis shows increased infiltration of monocytes and T-cells. Electrophoretic mobility shift assay showed increased NF-κB DNA binding activity in heart and kidney of dTGR. One-week treatment with DEX (1 mg/kg/d i.p.) initially increased blood pressure at week 5, compared to dTGR (191±2 vs.152±6 mm Hg, p<0.01), whereas blood pressure was not different at week 7 (193±15 vs. 182±8 mm Hg, p=0.8). However, DEX reduced 24 h albuminuria by 85 % (2.7±0.5 vs. 18.0±3.4 mg/d, p<0.001) and prevented mortality completely. Vasculopathy was ameliorated in kidney and heart and perivascular fibrosis was reduced. DEX inhibited NF-κB DNA-binding activity and also the NF-κB-regulated adhesion molecule ICAM-1. We also studied localization of NADPH subunit p22phox. Immunostaining of p22phox was detected in the endothelium and also colocalized with monocytes. DEX reduced both infiltration of cells and p22phox expression. Thus, these results demonstrate that DEX suppresses NF-κB binding activity, p22phox expression of infiltrated cells, inflammation, and protects against angiotensin II-induced end-organ damage, all without blood pressure reduction.
The Tnfα-Gene Locus and Body-Weight Response to a High-Fat Diet in Spontaneously Hypertensive Rats
Authors: Pausova Zdenka , Hamet Pavel , Pravenec Michal , Kren Vladimir
Published: July 2021

P192

Objective: Using linkage and association analysis, we have previously demonstrated that the TNFα−gene locus contributes to the determination of obesity and obesity-associated hypertension in hypertensive pedigrees of French-Canadian origin. The aim of the present study was to investigate whether the TNFα-gene locus is involved in the regulation of body weight (BW) response to a high-fat (HF) diet in spontaneously hypertensive rats (SHR). Methods: The effect of the TNFα−gene locus was investigated with the use of a congenic strain, SHR.1N, which differs from SHR by a segment of chromosome 20 originating from the normotensive Brown Norway rat and containing the TNFα gene. Sixteen-week-old SHR and SHR.1N were placed on either a normal (N; 5P14, Prolab 2500) or HF (F3282, Bio-Serv) diet for 12 weeks. BW was measured weekly. The BW response to the dietary intervention was assessed by three-way ANOVA with Strain (SHR and SHR.1N), Diet(N and HF) and Time (11 time points) as the main factors. Results: During the 12-week period, SHR (n = 16) and SHR.1N (n = 17) fed the HF diet increased their BW by 31% and 42%, respectively; and SHR (n = 13) and SHR.1N (n = 13) fed the N diet augmented their BW by only 18% and 19%, respectively. ANOVA demonstrated a significant effect of all three main factors, Strain (F
1,55
= 6.86, p = 0.01), Diet (F
1,55
= 85.69, p = 0.0001), and Time (F
10,550
= 236.12, p = 0.0001), and a significant three-way interaction between Strain, Diet and Time (F
10,550
= 2.58, p = 0.04). Subsequent two-way ANOVA showed that the effect of Strain and Time-Strain interaction was significant in rats fed the HF diet (F
1,31
= 11.01, p = 0.002; F
10,310
= 6.7, p = 0.0001, respectively), but not in rats fed the N diet (F
1,24
= 0.06, p = 0.8; F
10,240
= 1.31, p = 0.3, respectively). Summary and Conclusion: During feeding with the HF diet, both SHR and SHR.1N increased their BW, but the increase was greater in SHR.1N. These results suggest that a gene(s) exist(s) within the differential chromosomal segment of SHR.1N, which is involved in regulation of the BW response to the HF diet. Considering the known functional properties of TNFα, the TNFα gene is the best candidate within the segment.
Abstract 106: Paradoxical Increase in Office-Based Blood Pressure Measurement After a Brief Patient Rest Period
Authors: Karumbaiah Keerthana , Omar Nidal , Omar Bassam A
Published: July 2021

BACKGROUND:
Office-based blood pressure (BP) measurement is a snapshot of a patient’s ambulatory BP, and is subject to variations which may influence management.

OBJECTIVE:
To assess the effect of a brief rest period on repeat BP measurement.

METHODS:
Patient charts reviewed in University-based cardiology clinic identified 170 encounters which contained BP re-measurement data due to elevated initial BP of > 130/80 mmHg. BP was measured initially by a nurse, with the patient in a sitting position and the arm resting at the level of the heart. If BP was > 130/80 mmHg, it was repeated by physician after resting the patient for 15 minutes. Mean age was 64 ± 12 years.

Results:
Among encounters with BP re-measurement, initial systolic BP (SBP) was 153 ± 27 mmHg, and diastolic BP was 87 ± 16 mmHg. Upon re-measurement, 106 of 170 patients (62%) had lower SBP of 143 ± 23 mmHg compared with initial SBP of 162 ± 28 mmHg; a mean drop of 18 mmHg. However, 53 of 170 patients (31%) had higher SBP of 149 ± 17 mmHg compared with initial SBP of 138 ± 14 mmHg; a mean increase of 10 mmHg. Eleven patients (7%) had no BP change. In 50% (85/170) of encounters, BP re-measurement necessitated hypertensive medication changes. Compared with the remaining patients, those with paradoxical increase in BP were younger (60 ± 9 years versus 66 ± 13 years; p < 0.01), more females (57% versus 47%), and with lower initial SBP (134 ± 14 versus 160 ± 28, p < 0.01).

DISCUSSION:
Hypertension is a challenging public health problem. JNC 7 guidelines recommend that prior to BP measurement, persons should be seated quietly for at least 5 minutes in a chair, with feet on the floor, and arm supported at heart level; this may decrease initially elevated BP. However, 30% of our patients exhibited a paradoxical response, with elevation of the SBP after a 15 minute period of rest. The cause of this paradox is not clear, but may have resulted from white-coat hypertension during the rest period, which may be more common in younger patients, especially females, as noted in our study. This underscores the importance of ambulatory BP monitoring, especially in subsets of patients prone to having labile or white coat hypertension, to avoid the cost and side effects of BP overtreatment.
Abstract 126: Transgenic Hyperactivity of the Brain Renin-Angiotensin System Causes Vasopressin-Dependent Hypertension
Authors: Littlejohn Nicole K , Siel Rick B , Ketsawatsomkron Pimonrat , Pelham Christopher J , Hilzendeger Aline M , Buehrer Beth A , Weidemann Benjamin J , Li Huiping , Davis Deborah R , Thompson Anthony P , Liu Xuebo , Cassell Martin D , Sigmund Curt D , Grobe Justin L
Published: July 2021

Hypertension in many animal models is sensitive to inhibition of the brain renin-angiotensin system (RAS). We examined mice with transgenic hyperactivity of the brain RAS (sRA mice) to determine whether this manipulation is sufficient to cause hypertension, and to identify the causative mechanism. sRA mice exhibit brain-specific increases in angiotensin (ANG) peptide production through neuron-specific expression of human renin (synapsin promoter) and expression of human angiotensinogen through its own promoter. We determined both through tail-cuff and radiotelemetric methods that sRA mice are hypertensive (SBP; control 112±2 vs sRA 127±5 mmHg, P=0.02). Despite normal plasma osmolality and moderate hyponatremia, sRA mice exhibit double the number of vasopressin-expressing neurons in the supraoptic nucleus (P=0.002), as detected by immunohistochemistry. Plasma levels of the vasopressin pro-segment, copeptin, were reduced in sRA mice (140±19 vs 68±21 pg/mL, P=0.02), which correlated with severe polyuria (1.8±0.3 vs 12.3±1.6 mL/day, P<0.001). Indeed, total daily copeptin loss in the urine was significantly increased almost twenty-fold in sRA mice (7.9±4.3 vs 154.4±62.4 pg/day, P=0.03), highlighting an increase in vasopressin secretion per unit time. The baseline hypertension of sRA mice was completely reversed by chronic infusion of the dual V
1A
/ V
2
receptor antagonist, conivaptan (22 ng/hr, 10 days, s.c.; 113±5 mmHg, P=0.02). Preliminary experiments demonstrate that infusion of the selective V
2
receptor antagonist, tolvaptan (22 ng/hr, 10 days, s.c.), has similar effects. Further, while abdominal aorta and mesenteric arteries demonstrate selective desensitization to vasopressin and down-regulation of the V
1A
receptor (38% of control, P<0.05), renal V
2
receptor expression remained normal in sRA mice. Together, these data demonstrate major roles for vasopressin and its V
2
receptor in the hypertension caused by elevated brain RAS activity.
Abstract 127: Identification of a Region of Rat Chromosome 1 That Impairs the Myogenic Response and Cerebral Blood Flow Autoregulation in Fawn Hooded Hypertensive Rats.
Authors: Pabbidi Mallikarjuna R , Juncos Julio , Renic Marija , Tullos Hurtis J. , Lazar Jozeph , Harder David R. , Jacob Howard , Roman Richard J.
Published: July 2021

This study examined the effect of transfer of a 2.4 Mbp region of Brown Norway (BN) rat Chr 1 into the Fawn Hooded Hypertensive (FHH) genetic background on autoregulation (AR) of cerebral blood flow (CBF) and the myogenic response of isolated middle cerebral arteries (MCA). Autoregulation of CBF measured by laser Doppler flowmetry was poor in FHH rats (AR index (AI), 0.8±0.1) and in FHH.1BN congenic strains which excluded the critical region (AR-: AI, 0.9± 0.1). In contrast, autoregulation of CBF was completely restored by transfer of the region of BN Chr 1 between 258.8 to 261.2 Mbp in AR+ FHH.1BN congenic strains (AI, 0.3 ± 0.1). The diameter of MCA of FHH rats and AR- congenic strains increased by ∼10% (140 ± 1 to 157± 2 μm), when transmural pressure was increased from 40 to 140 mmHg. In contrast, the diameter of the MCA in AR+ congenic strain fell from 127 ± 2 to 65 ± 1 μm. Whole-cell patch-clamp of cerebral VSM cells revealed a 4.3-fold increase in BK channel current densities at depolarized potentials in FHH versus AR+ rats (105 ± 2 versus 24 ± 4 pA/pF at +80mV). Using single channel analysis we found that the increase in BK channel current was largely due to a marked increase in the NPo of BK channel in FHH as compared to AR+ rats (0.9 ± 0.1 and 0.2 ± 0.1 at +80mV). To explore the significance of the impaired myogenic response, we compared changes in CBF and infarct size following transient occlusion and reperfusion of the MCA in FHH rats and the AR- and AR+ congenic strains. Occlusion of MCA reduced CBF similarly in all the strains. However, the hyperemic response following reperfusion in FHH and AR- strains was significantly greater and more prolonged than that seen in AR+ rats (AR-: 173 ± 1%, 45 min versus AR+: 124 ± 5%, 15 min). Moreover, infarct size and edema formation was significantly greater in the AR- congenic strain (39 ± 3 % and 12 ± 2 %) in comparison to that seen in the AR+ strain (28 ± 2 %; 7 ± 1%). These results indicate that there is a gene that plays a critical role in the regulation of the myogenic response of the cerebral vasculature by altering BK channel activity in the critical 2.4 Mb region of Chr 1 containing just 15 genes and that transfer of this region from BN to FHH rats restores autoregulation of CBF, vascular reactivity and reduces infarct size following ischemia/reperfusion injury.
Abstract 144: Increased CaMKII Activity in Hypertensive Vascular Endothelium
Authors: Charbel Chimene , Toussaint Fanny , Blanchette Alexandre , Ledoux Jonathan
Published: July 2021

The Ca2+-calmodulin dependent protein kinase II (CaMKII) plays a prime role in the development of cardiovascular diseases including heart failure and diabetes-associated vasculopathies. The multifunctional kinase can promote the genesis or sustainment of cardiovascular pathological conditions. Although the role of cardiac CaMKII is well established, literature on endothelial CaMKII is only emerging. Recent studies showed that CaMKII activation could alter expression and activity of enzymes such as eNOS suggesting that CaMKII might be involved in endothelial dysfunction. A better understanding of CaMKII signalling will lead to the improvement of cardiovascular therapies. CaMKII act as a Ca2+ sensor by its ability to decode oscillatory Ca2+ signalling through complex autophosphorylation steps. Such oscillatory Ca2+ signalling has only recently been reported in endothelium, the Ca2+ pulsars. The Ca2+ pulsars might represent a novel and distinctive activation mechanism for endothelial CaMKII. This study is aimed to elucidate the correlation between endothelial Ca2+ dynamics and CaMKII activity in microvasculature. PCR experiments showed that all four mammalian CaMKII isoforms are expressed in small murine mesenteric arteries but only variant 1 of CaMKIIβ have been identified. However, confocal microscopy revealed that only CaMKIIα, β and δ can be found in endothelial cells and only δ and γ in vascular myocytes. Moreover, α and β specifically converged at Ca2+ pulsar sites and stimulation of Ca2+ pulsars increased CaMKII clustering. Activated CaMKII (T286) also showed similar distribution. These evidences suggest that Ca2+ pulsars activate CaMKII. Our results showed that spontaneous Ca2+ pulsars are increased (54%) in arterial hypertension (AH) and can stimulate basal CaMKII activity. Indeed, CaMKII clustering is increased in AH (2 fold). However, an inverse correlation between CaMKIIβ expression and blood pressure was established (r2=0.6760), suggesting that blood pressure significantly alters expression of the kinase. This study demonstrates that CaMKII activity and expression is significantly modulated in hypertension and provides evidences that CaMKII represent an interesting therapeutic approach for vascular pathologies.
Abstract 146: Relation Between Noninvasive Vascular Function Assessment Methods in Healthy and Obese Adults
Authors: Dickinson Kacie , Clifton Peter , Keogh Jennifer
Published: July 2021

Peripheral arterial tonometry (PAT) is a novel method of non-invasive endothelial function assessment. However the physiology underlying PAT and its relationship to established methods of assessment not clear. Therefore we evaluated the relationship between PAT in the digital microcirculation with an established method of ultrasound assessment of flow-mediated dilatation (FMD) in the brachial artery in a sample of healthy and obese subjects. We also compared the augmentation index (AIx) derived from PAT and compared this with AIx derived by radial applanation tonometry (SphygmoCor). Using a cross-sectional design 16 healthy individuals (age 36±16years; BMI 25±5kg/m
2
) and 14 overweight and obese patients (age 57±7years; BMI 31±6kg/m
2
) were examined. Vascular function was assessed using FMD and PAT techniques simultaneously after an overnight fast. 14 overweight subjects had augmentation index (AIx) assessed using radial applanation tonometry immediately prior to PAT and FMD procedures. Bivariate correlation analysis was used to assess the relationship between variables. No significant correlations between fasting FMD and PAT were observed in the healthy (r=0.249 p=0.372) or overweight and obese group (r=-0.345 p=0.227). There was no correlation between the endothelium-independent responses to nitroglycerin measured by PAT and brachial ultrasound (r=0.357 p=0.210). AIx derived from EndoPAT was significantly correlated with AIx values obtained with Sphygmocor (r=0.770 p=0.001). In conclusion AIx derived from SphygmoCor and EndoPAT were significantly correlated however PAT and FMD were not related in healthy or obese adults. This may be due to differing vascular biology of the PAT response to hyperaemia in the digital circulation compared with the FMD response measured in conduit vessels. PAT as a method of endothelial function assessment requires further validation in population sub groups.
Abstract 156: Gender Differences Related to Increased Vascular Age in Hypertensive Patients
Authors: Casanova Marcela , Trindade Michelle , Cunha Ana Rosa , DEl-Rei Jenifer , Medeiros Fernanda , Oigman Wille , Neves Mario F
Published: July 2021

Background:
Vascular age (VA) has been increasingly considered in the evaluation of hypertensive patients but the gender differences have not established yet.

Objective:
To characterize gender differences in clinical and vascular parameters in treated hypertensive patients with increased vascular age.

Methods:
A cross-sectional study was carried out to evaluate hypertensive patients on stable drug therapy, both genders, aged 30-74 years. Blood pressure (BP) was measured and ultrasonography was performed to evaluate brachial flow-mediated dilation (FMD). Carotid-femoral pulse wave velocity (cfPWV) was obtained by Complior SP and normalized by mean BP (cfPWV-N). The 10-year risk for general cardiovascular disease from Framingham Heart Study was used to calculate VA. The median of VA was 76 years, and the study population was divided into four groups: women with lower vascular age (LVA, < 76 years, n=50) or higher vascular age (HVA, ≥ 76 years, n=82), men with LVA (n=26) or HVA (n=27).

Results:
Mean age was similar between men and women with HVA (62±5 vs 60±6 years) and with LVA (49±8 vs 51±8 years). LVA men presented greater systolic BP (143±15 vs 132±16 mmHg, p<0.01) compared to LVA women, but no difference between gender was observed in HVA groups (154±15 vs 152±17 mmHg) and diastolic BP was similar in LVA (88±10 vs 88±13 mmHg) and in HVA (89±10 vs 92±14 mmHg) groups. Men with HVA presented greater cardiovascular risk (31±2 vs 18±6 %, p<0.001), cfPWV (12±2 vs 10±2 m/s, p<0.05), cfPWV-N (11±2 vs 9±2 m/s, p<0.05) compared to HVA women. FMD was significantly reduced in HVA women compared to LVA group (11±7 vs 6±5 %, p<0.01), but no significant difference was noted in men due to reduced values even in LVA group (8±5 vs 6±5 %). There was a stronger correlation of vascular age to systolic BP in women (r=0.56, p<0.001) than in men (r=0,30, p<0.05) although the correlation to cfPWV was stronger in men (r=0.45 and r=0.30, p<0.01 for both). On the other hand, VA was inversely correlated to brachial FMD only in women (r=-0.28, p<0.05).

Conclusion:
In this population of treated hypertensive patients, men seem to develop endothelial dysfunction earlier than women, and vascular stiffness is more exacerbated in men with higher vascular age, showing more advanced vascular disease in this gender.
Abstract 157: The Sex-Specific Influence of Adiposity on Blood Pressure During Physical and Mental Challenges in Adolescence
Authors: Van Woudenberg Mariel , Syme Catriona , Abrahamowicz Michal , Leonard Gabriel , Perron Michel , Richer Louis , Veillette Suzanna , Gaudet Daniel , Paus Tomas , Pausova Zdenka
Published: July 2021

Greater blood pressure (BP) reactivity and slower BP recovery from physical and mental challenges predict future hypertension. Males exhibit higher BP than females throughout their reproductive age and, as such, have a higher prevalence of hypertension. Excess body-fat is a major risk factor for hypertension in both males and females. We investigated whether BP reactivity and recovery from physical and mental challenges differ between adolescent males and females, and whether these hemodynamic parameters are associated with resting BP and are influenced by excess body-fat in a sex-specific manner. In 285 male and 311 female adolescents (age 12-18 years), we quantified visceral fat (VF) with magnetic resonance imaging and total body fat (TBF) with bioimpedance and measured systolic BP (SBP) beat-by-beat at rest and during physical (10-min standing) and mental (2-min math test) challenges. Our results showed that in both sexes, BP reactivity and BP recovery for both challenges (adjusted for age, height and initial BP) correlated closely with resting BP (0.03 ≤ r2 ≤ 0.34). In addition, for both physical and mental challenges, males versus females showed greater BP reactivity (by 3.5 mm Hg, p<0.0001 and by 2.6 mmHg, p=0.02, respectively) and no difference in BP recovery. VF correlated positively with BP reactivity to the physical challenge only and in males only (r=0.18, p=0.007), and this correlation was independent of TBF (r=0.21, p=0.002). Consistent with these results, additional adjustment for VF diminished the sex difference in BP reactivity to the physical but not mental challenge (from 3.5 to 2.7 mm Hg, p=0.01). No relationship was observed between VF and BP recovery from either challenge and in either sex. This is the first study to show sex differences exist not only in BP adaptation to daily activities, but also in the way VF influences this adaptation. Overall, our findings suggest the need for sex-specific prevention and treatment of hypertension.
Abstract 159: Role of Melanocortin 3/4 Receptor (MC3/4R) in a Model of Postmenopausal Hypertension.
Authors: Maranon Rodrigo O , do Carmo Jussara , Lima Roberta , Reckelhoff Jane F
Published: July 2021

The mechanisms responsible for hypertension in postmenopausal women have not been completely elucidated. We have shown previously that MAP in old female SHR is mediated in part by sympathetic activation. In male SHR leptin causes sympathetic activation via the melanocortin 3 / 4 receptor (MC3/4R) activation, and MC3/4R blockade reduces their blood pressure. The hypothesis of the present study was that MC3/4R also contributes to hypertension in old female SHR. Female SHR (aged 18 mos, n=6) received MC3/4 receptor antagonist SHU-9119 (1 nmol/h via minipump) or saline vehicle (n=5 controls). After two weeks recovery, MAP and heart rate (HR) were measured for 5 days during baseline period, and then rats received SHU 9119 or saline icv, and MAP and HR were recorded for 7 days. MC3/4R antagonism produced an increase in food intake (17.1±2 gr, n=5, vs 26.6±1 gr, n=6, p<0.001) and body weight (217±11 gr,n=5 vs 256±6 gr, n=6; p<0.001), compared to saline controls. However, MC3/4R antagonism had no effect on MAP (baseline period: 174±10 mmHg ,n=4 vs 181±5 mmHg, n=6; p:NS; treatment period, 175±13 mmHg, n=4 vs 172±10 mmHg, n=6; p:NS) or HR (Baseline period: 344±4 bpm, n=4 vs 357±12 bpm, n=6; Treatment period, V-R:345±9 bpm, n=4 vs 332±9 bpm, n=6; p:NS). These results show that MC3/4R plays no role in sympathetic activation and regulation of BP in old female SHR. These data suggest that aging women may need different antihypertensive medications than do men. Supported by NIH HL69192, HL55901; HL66072.
Abstract 189: Omeprazole Decreases Chronic Antihypertensive Effects of Sodium Nitrite
Authors: Pinheiro Lucas C , Amaral Jefferson H , Ceron Carla S , Ferreira Graziele , Tanus-Santos Jose E
Published: July 2021

Introduction:
Recent studies showed that sodium nitrite decreases blood pressure (BP) in two kidney, one clip (2K1C) hypertension, probably as a result of nitrite being converted into nitric oxide in the acid environment of the stomach. This study aimed at examining whether increasing gastric pH with omeprazol reduces the chronic antihypertensive effects of nitrite.

Methods:
2K1C hypertensive and sham operated control rats were treated with omeprazole (10mg/Kg; i.p.) or vehicle and sodium nitrite (15mg/Kg; gavage) or saline for two weeks. Systolic BP (SBP) was measured by tail pletismografy weekly. Circulating nitrite levels were measured by chemiluminesce and gastric pH was measured with an electrode. The results were analyzed by two-way ANOVA. The results are show as mean ± standard deviation.

Results:
2K1C rats were hypertensive two weeks after surgery (SBP=180±17 mmHg). After 4 weeks of treatment, nitrite exerted antihypertensive effects in rats treated with vehicle (SBP=161±23 mmHg
versus
200±29 mmHg, respectively, in the 2K1C+nitrite and in the 2K1C+saline groups; P<0.05). However, nitrite exerted no antihypertensive effects in 2K1C rats treated with omeprazole (SBP=200±34 mmHg; P>0.05
versus
2K1C+saline group). We found no significant differences among the sham operated groups. Similar increases in plasma nitrite concentrations were found when animals treated with nitrite and omeprazol were compared with those treated with nitrite and vehicle (8.5±4.1
versus
5.2±3.6 μM, respectively; P>0.05). Omeprazole increased gastric pH in all animals treated with this drug (P<0.05).

Conclusion
Treatment with omeprazole blunts the chronic antihypertensive effects of sodium nitrite in 2K1C rats. However, this effect is probably not associated with significant differences in plasma nitrite concentrations.
Abstract 20: Angiotensin Suppresses Thermogenic Capacity Through Adipose AT2 Receptors
Authors: Grobe Justin L , Park Sungmi , Littlejohn Nicole K , Buehrer Beth A , Weidemann Benjamin J , Keen Henry L , Liu Xuebo , Sigmund Curt D
Published: July 2021

Selective induction of the brain renin-angiotensin system (RAS) results in hypertension, polydipsia, and elevated resting metabolic rate. Transgenic sRA mice exhibit brain-specific RAS hyperactivity through expression of human renin via the synapsin promoter, and human angiotensinogen via its own promoter. The circulating RAS in these animals is suppressed due to chronic hypertension, and the elevated resting metabolic rate of sRA mice is sensitive to peripheral propranolol or angiotensin replacement. Cultured 3T3L1 adipocytes exhibited a dose-dependent induction of uncoupling protein 1 (UCP1) by the AT
2
receptor (AT
2
R) antagonist, PD-123,319, and suppression by the AT
2
R agonist, CGP-42112a (CGP). UCP1 mRNA was specifically induced within inguinal adipose of sRA mice (25-fold, P=0.02). Treatment of sRA mice with CGP (50 ng/kg/min, 8 weeks, s.c.) normalized metabolic rate (control 2.8±0.2, sRA 3.6±0.2, sRA+CGP 3.1±0.2 mL O
2
/100g/min) and inguinal UCP1 mRNA (sRA 24.6 vs sRA+CGP 4.6-fold of control, P=0.02), blood pH (control 7.26±0.02, sRA 7.37±0.03, sRA+CGP 7.28±0.06), bicarbonate (control 22±1, sRA 31±1, sRA+CGP 21±6 mM) and perigenital adipose mass (control 317±100, sRA 127±16, sRA+CGP 590±127 mg). Fluid and sodium intake, urine volume and electrolytes, and heart and kidney masses were different in sRA mice but unchanged by CGP treatment, and food intake was unchanged in all groups, highlighting the specificity of effects elicited by CGP. We conclude that AT
2
R activation blunts the thermogenic response to increased brain RAS activity. Interestingly, sRA gain weight at the same rate as control mice when fed a high fat diet, prompting the hypothesis that an elevated circulating and/or adipose RAS may result in attenuated thermogenic responses during obesity. This may suggest a positive-feedback loop between the circulating RAS and adiposity, and identify adipose AT
2
R as a novel therapeutic target for obesity.
Abstract 215: An Agonistic Human Monoclonal Autoantibody to the β2-adrenergic Receptor: Implications in Postural Hypotension
Authors: Li Hongliang , Zuccolo Jonathan , Zillner Caitlin , Lee Jiyeon , Hill Michael , Cunningham Madeleine , Kem David , Yu Xichun
Published: July 2021

Functional autoantibodies directed to the autonomic receptors have been increasingly recognized to contribute to the pathophysiology of various cardiovascular diseases. However, to date, no human monoclonal autoantibodies to these receptors with agonist activity have been available. We have recently reported a subgroup of patients with idiopathic postural hypotension who have no known etiology are associated with vasodilatory autoantibodies to the β2-adrenergic receptor (β2AR). Using standard hybridoma techniques, we produced a β2AR-activating monoclonal autoantibody C5F2 from the peripheral blood lymphocytes of a patient with idiopathic postural hypotension and high ELISA antibody titers to a peptide corresponding to the second extracellular loop (ECL2) of β2AR. C5F2 was of the IgG3 isotype and recognized an epitope located at the N-terminus of β2AR ECL2 as determined by epitope mapping using multipin peptide synthesis. Confocal immunofluorescence revealed C5F2 binding to the β2AR in Chinese hamster ovary (CHO) cells transfected with human β2AR and rat cremaster arterioles, both of which were inhibited by presabsorption with the β2AR ECL2 peptide. Functionally, the C5F2 IgG stimulated cyclic AMP production in β2AR-expressing CHO cells in a dose-dependent manner (0.005-5 mg/ml). C5F2-induced cyclic AMP activation was specifically blocked by both the β2AR ECL2 peptide and β2AR selective antagonist ICI-118551. In an isolated rat cremaster arteriole assay, infusion of the C5F2 IgG produced a potent vasodilation which was inhibited by the β2AR ECL2 peptide and β2AR blocker ICI-118551 (from 67.8±5.8% to 9.3±5.1% and 4.4±2.1% of maximal dilatory response, respectively), indicating that antibody activation of vascular β2AR may contribute to systemic vasodilation. These data support the concept that circulating agonistic autoantibodies serve as vasodilators and may cause or exacerbate orthostasis by altering the compensatory postural vascular response. The availability of this first human monoclonal autoantibody to the β2AR provides opportunities to identify previously unrecognized causes and new pharmacological management of postural hypotension.
Abstract 224: Differential Actions of Angiotensin II on Proximal Tubule Transport
Authors: Panico Carolina , Rudolph Earl H , Blantz Roland C , Capasso Giovambattista , Wilcox Christopher S , Welch William J
Published: July 2021

Studies with the proximal tubule-specific angiotensin type 1 receptor (AT
1
R) knockout mouse have shown that the proximal tubule (PT) contributes to Ang II-induced hypertension. Ang II levels in the PT fluid are 100- to 1000-fold higher than in plasma, yet the function of the AT
1
-Rs on the luminal side of the PT is unclear. Moreover, hemodynamic actions of Ang II that raise the filtration fraction and the peritubular fluid uptake forces also stimulate PT fluid uptake. We tested the effects of Ang II and AT
1
-Rs on PT fluid uptake in rats. Ang II (200 ng/kg/min) delivered for 2 weeks increased MAP (Con: 95±9 vs Ang II: 140±5 mmHg, p<0.001), single nephron GFR (snGFR)(Con: 36±3 vs Ang II: 43±3, p<0.05) and absolute proximal reabsorption (APR) (Con: 20±3 vs Ang II: 34.5±6.5 nl/min, p<0.01), measured by free flow collections in the S2 segments of the PT in Sprague Dawley (SD) rats. These effects were normalized by acute reduction of MAP via a supra-renal aortic clamp. In a separate group of Munich Wistar Frömter (MWF) rats, which have surface glomeruli, Ang II increased snGFR and APR in the S1 segment (Con: 19±4 vs AngII: 44±5 nl/min, p<0.01; +125±9 %) substantially more than in the S2 segment (Con: 25±6 vs Ang II 37±7 nl/min, p<0.01; +48±6 %). In microperfusion and recollection experiments, in which snGFR was controlled, fluid uptake (Jv) in the PT of SD rats was reduced dose-dependently by Ang II delivered directly into the lumen of S2 segments. Ang II (10
-9
M) at physiological levels reduced Jv by 60±7%. This effect on Jv was blocked by co-perfusion of an AT
1
R blocker. Ang II (10
-9
M), microperfused directly into the S2 reduced Jv in MWF rats as well by 44±5%. Ang II in cultured PT cells at higher concentrations (10
-7
to 10
-9
M) also reduced
22
Na
+
uptake by 20-35%. In conclusion, enhanced PT fluid reabsorption by Ang II is due to hemodynamic enhancement that likely entails peritubular fluid uptake primarily in the S1 segment. However, luminal Ang II acting on AT
1
-Rs in the S1 and S2 segments of the PT reduces fluid uptake. This effect could be overridden by the hemodynamic effect of systemic Ang II to increase reabsorption especially in the S1 segment.
Abstract 231: Angiotensin-(1-9) Antagonises Cardiac Remodelling in a Mouse Model of Angiotensin Ii-induced Hypertension.
Authors: Flores Monica , Graham Delyth , Dominiczak Anna F , Milligan Graeme , Baker Andrew H , Nicklin Stuart A
Published: July 2021

The identification of angiotensin converting enzyme-2 (ACE2), generating angiotensin-(1-7) [Ang-(1-7)] which signals via the Mas receptor to inhibit pathophysiological effects in cardiovascular disease has led to the definition of a counter-regulatory axis of the renin angiotensin system (RAS). Recently, we showed that another angiotensin peptide, Ang-(1-9), may also be part of this counter-regulatory axis as it prevents cardiomyocyte hypertrophy via the angiotensin type 2 receptor (AT2R). Furthermore, infusion of Ang-(1-9) via osmotic minipumps into stroke-prone spontaneously hypertensive rats reduced cardiac fibrosis via the AT2R. Here, we investigated Ang-(1-9) in an acute model of AngII-induced hypertension in C57BL/6J mice. Ang-(1-9), Ang-(1-9)+PD123,319 (AT2R antagonist), or water (control) were co-infused with AngII for 2 weeks via osmotic minipumps. Blood pressure was monitored via radiotelemetry. Significant increases in mean arterial pressure were observed in AngII infused mice compared to control (control 108.8±5.7 mmHg; AngII 125.1± 8.4 mmHg; p>0.05) however co-infusion of Ang-(1-9) or Ang-(1-9) and PD123,319 did not affect AngII-induced hypertension (AngII+ Ang-(1-9) 122.4±10.3 mmHg; AngII+Ang-(1-9)+PD123,319 118.3±mmHg; n=6 mice). When assessing cardiac hypertrophy by heart weight/tibia length ratio Ang-(1-9) reduced AngII-induced cardiac hypertrophy (ratio heart weight/tibia length: control 9.4 ± 1.2; AngII 11.9 ± 0.6; AngII+Ang-(1-9) 8.2 ± 0.7; p<0.01). Sections of heart were stained with wheat germ agglutinin and cardiomyocyte size measured supporting an anti-hypertrophic effect of Ang-(1-9) via the AT2R (control 25.7±3.8 μm; AngII 28.8±3.8 μm; AngII+Ang-(1-9) 24.6±4.8 μm; AngII+Ang-(1-9)+PD123,319 27.7±3.2μm; p<0.05). Furthermore, quantification of fibrosis following staining with picrosirius red also showed a significant reduction in animals co-infused with Ang-(1-9) and AngII compared to AngII-infusion (p<0.05). Further studies are ongoing to analyse cardiac effects of Ang-(1-9) at gene and protein level. These data support a direct biological role for Ang-(1-9) in cardiac remodeling and highlights Ang-(1-9) as a potential new therapeutic target in cardiovascular disease.