bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract 296: Norepinephrine Evoked Salt-Sensitive Hypertension Results in Impaired NCC Function, but Not Expression
Authors: Walsh Kathryn , Mahne Sarah , Kuwabara Jill T , Wainford Richard D
Published: July 2021

Aim:
Recent controversial studies have proposed that excess norepinephrine (NE) evokes impaired NCC regulation to drive salt-sensitive hypertension. The following studies examine the impact of excess NE on salt-sensitivity and sodium homeostasis in conscious Sprague-Dawley (SD) rats.

Methods:
Naïve male SD rats, rats receiving a s.c. vehicle infusion (DMSO/Saline, 50:50), or rats receiving a s.c. NE infusion (600ng/min) were fed a 0.4% (NS) or 8% NaCl (HS) diet for 14 days. Additional rats received s.c. hydrochlorothiazide (HCTZ, 4mg/kg/d) in combination with NE (600ng/min) for 14 days on HS. On day 14, MAP, FENa, MAP response to i.v. hexamethonium (30mg/kg), and peak natriuresis to i.v. HCTZ (2mg/kg) infusion were assessed (N=4/gp). A PCR array examining NCC associated genes was performed on kidney cortex samples from each group.

Results:
NE increased MAP, FENa and vascular sympathetic tone (MAP [mmHg] NS 127±2, NE+NS 151±3, p<0.05). We observed no difference between the naïve and vehicle rats. A HS diet exacerbated NE induced hypertension (MAP [mmHg] HS 129±2, NE+HS 172±4, p<0.05), reduced FENa and prevented a salt stimulated reduction in HCTZ evoked natriuresis. Co-infusion of HCTZ with NE abolished the salt-sensitive component of NE-induced hypertension (MAP [mmHg] NE+HCTZ+HS: 152±3, p<0.05). PCR analysis revealed a significant increase in serine/threonine kinase 39 (0.83-fold increase vs. Naïve SD on NS) mRNA in NE+HS rats. We did not see NE or HS evoked changes in OSR-1, WNK4 or NCC mRNA in any group.

Conclusion:
The results support previous studies in mice and highlight an opposing interaction between excess NE and high salt intake on sodium homeostasis which exacerbated NE-induced hypertension via a mechanism independent of NE-mediated vascular constriction. Physiologically, our results show impaired NCC function, supporting previous data. In contrast, we failed to detect elevated NCC or WNK4 mRNA in response to NE infusion contradicting data generated in mice and suggesting a key role of altered NCC phosphorylation versus expression in NE treated rats.
Abstract 311: Nifedipine Attenuates Abdominal Aortic Aneurysm in Ang II-infused hph-1 Mice
Authors: Miao Xiaoniu , Siu Kin Lung , Cai Hua Linda
Published: July 2021

We have previously shown that angiotensin II (Ang II) perfusion of hph-1 mice results in development of severe abdominal aortic aneurysm (AAA, 79% within 2 wks) that is associated sudden death and regulation of blood pressure. This phenotype can be completely attenuated by recoupling of eNOS with oral folic acid (FA) administration, which restores eNOS cofactor tetrahydrobiopterin (H4B) bioavailability via restoration of endothelial H4B salvage enzyme dihydrofolate reductase (DHFR). In view of the unclear relationship between blood pressure and AAA formation, we investigated the potential effects of L-type calcium channel blocker (CCB) Nifedipine (Nif) on AAA formation using the Ang II infused hph-1 model. Six-month old hph-1 mice were infused with Ang II (0.7 mg/kg/day) for 2 wks using Alzet osmotic pumps. The animals were fed Nif chew (20 mg/kg/day) two days prior to Ang II infusion and throughout the study period of 2 wks. Of note, the incidence rate of AAA dropped from 79% to 21% (2 out of 13). The Ang II induced hypertension (telemetry) and expansion of abdominal aorta (ultrasound) in hph-1 mice were abolished by Nif diet. Increased aortic reactive oxygen species (ROS) production (DHE) was also attenuated by Nif administration. L-NAME sensitive superoxide production, reflective of eNOS uncoupling activity, was measured by electron spin resonance (ESR). Treatment with Nif restored eNOS function completely, resulting in -2.49± 0.71 fold change in L-NAME sensitive superoxide production. Our previous data demonstrated extensive eNOS uncoupling activity (>10 fold) in Ang II-infused hph-1 mice that is attenuated by restoration of endothelial DHFR function (Hypertension 2012). Nif treatment also markedly improved NO bioavailability (ESR) by 2.42± 0.23 fold. These data demonstrate that an oral treatment of Nif is effective in correcting eNOS dysfunction to attenuate AAA formation. Although it does not differentiate the contributions from attenuation of oxidative stress and blood pressure lowering, it once again suggests that eNOS uncoupling can an important mediator of AAA formation.
Abstract 33: Atorvastatin Downregulates Vascular Nox Expression and Ameliorates Oxidative Stress-associated Inflammatory Process in Type 2 Diabetic Db/db Mice
Authors: Bruder-Nascimento Thiago , Callera Glaucia , Montezano Augusto , He Yeng , Antunes Tayze , Nguyen Dinh Cat Aurelie , Tostes Rita de Cassia , Touyz Rhian M
Published: July 2021

Nox-derived reactive oxygen species generation plays a role in endothelial dysfunction and vascular inflammation, which underline vascular damage observed in diabetes. Increasing evidence indicates that the beneficial effects of atorvastatin are associated with antioxidant mechanisms. We tested the hypothesis that atorvastatin influences Nox isoforms expression and ameliorates diabetes-associated vascular inflammation and redox signalling. Diabetic mice (db/db model of obesity and diabetes type II) and their control counterparts (db/+) were treated with atorvastatin (10 mg/Kg/day, p.o., 2 weeks). No differences were observed in BP among the groups. Improved oral glucose tolerance was observed in atorvastatin-treated db/db group (area under curve, db/db: 2858 ± 81 vs db/db atorvastatin: 2251 ± 158). Atorvastatin lowered plasma thiobarbituric acid-reacting substances levels in db/db mice (db/+: 4,7 ± 0,7 ;db/db: 6,5 ± 1,1 vs db/db atorvastatin: 4,9 ± 0,5 ). Increased expression of Nox1, 2 and 4 (1 to 3 fold increase vs db/+) and the associated enhance of ROS generation in the vasculature of db/db mice (db/+: 4312 ± 874; db/db: 27828 ± 8215 vs db/db atorvastatin: 8742 ± 2393 RLU) were abrogated by atorvastatin. The increase of vascular p47phox and RAC1/2 membrane translocation observed in db/db mice was also inhibited by atorvastatin. Diabetes-associated increase of VCAM-1 expression, NFkB p65 phosphorylation, and vascular monocyte adhesion were reduced by aotrvastatin treatment. Higher MAP kinase phophorylation levels observed in db/db mice were blunted by atorvastatin. Impaired vascular responses to acetylcholine (maxium effect %; db/+: 83 ± 5,1 ;db/db: 48 ± 6,4 vs db/db atorvastatin: 75 ± 5,2) and insulin (maxium effect %; db/+: 103 ± 7,5 ;db/db: 47 ± 2,0 vs db/db atorvastatin: 95 ± 7,1) in db/db mice were normalized by atorvastatin treatment. Our results demontrate that atorvastatin ameliorates oxidative stress and inflammatory process in db/db mice. Findings from this study identify NADPH oxidase as a target for atorvastatin. We describe novel mechanisms whereby statins may improve vascular function in obesity-associated diabetes.
Abstract 353: Clinical Significance of Low Normal Serum Potassium Concentrations in the Diagnosis of Aldosterone Producing Adenoma
Authors: Iwakura Yoshitsugu , Morimoto Ryo , Kudo Masataka , Ono Yoshikiyo , Tsukada Yasuko , Matsuda Ken , Nezu Masahiro , Ito Sadayoshi , Satoh Fumitoshi
Published: July 2021

Introduction
The number of PA patients is gradually increasing, because screening has been become active in general clinicians. Plenty of patients with PA, however, still have been undiagnosed and threatened by cardiovascular morbidities. Especially, patients with Aldosterone Producing Adenoma(APA) should be screened as early as possible to prevent from them. Therefore, we believed that useful marker not to miss APA has been hoped by general clinicians. Recent studies showed that serum potassium (sK) showed significantly lower in APA than in primary hypertension (PH), although the prevalence of hypokalemia is getting lower than previous in PA patients. In the present study, we retrospectively investigated to find the optimal cut-off value (CV) of sK among all hypertensive patients referred to our hospital for detecting APA, on the hypothesis that it might be significantly lower in APA than in PH instead of the administration of any hypertensive agents.

Patients
All 169 patients undergone adrenal vein sampling and diagnosed with APA by pathological exams after surgery were recruited. PA was screened by elevated value of ARR (>20; PAC in ng/dl and PRA in ng/ml/hr) at baseline, and diagnosis was confirmed by the elevated ARR(>20) after loading captopril. PH (n=194) was defined as below 20 of baseline ARR and ruled out other secondary hypertensions.

Study protocol
Patients were compared their parameters in each combination of agents shown as next. 1. All agents. 2. Only ACE-I and/or ARB were essentially included. 3. Diuretics and beta blockers were included in addition to agents of Study 2. In each study, Calcium channel blockers and alpha blockers were optionally allowed. ROC curve analysis was performed for each study.

Results
1. The best CV was 28.1 in ARR. The sensitivity (SE) and specificity (SP) were 86% and 85%, respectively. 2. The best CV was 3.7mM in sK. SE and SP were 83% and 98%, respectively. 3. The best CV was 3.8mM in sK. SE and SP were 79% and 91%, respectively. In each study, the rate of above 140 mM in serum sodium (sNa) was 98%(165 of 169), 97%(29 of 30), and 98%(65 of 66), respectively.

Conclusion
For effective detection of APA, we propose that patients whose sK are below 3.8mM and sNa are above 140mM with ACE-I/ARB treatments should be referred to special clinicians.
Abstract 360: Increased Aldosterone Sensitivity in Young Blacks
Authors: Tu Wanzhu , Liu Hai , Eckert George , Pratt J Howard
Published: July 2021

Aldosterone contributes to the elevation of blood pressure (BP) by acting on the distal tubule to cause greater sodium retention and volume expansion. Blacks, in comparison with whites, have lower plasma aldosterone concentrations (PAC), possibly due to increased sodium reabsorption and resultant renin suppression, as evidenced by their lower plasma renin activity (PRA); but BP is on average higher in blacks. The seemingly different BP-PAC relationships in blacks and whites raise point to the possibility of different aldosterone sensitivity in the two race groups. Using data from a cohort of normotensive youths (n=654 observations contributed by 537 subjects), we used a varying coefficient model to examine the BP effect of PAC at different levels of PRA in blacks and whites. We characterized the effects of PAC as a function of PRA and assessed its effect on age, sex, and height-adjusted BP percentile. The estimated effects are presented graphically (Figure 1 a&b). Blacks had lower PRA and PAC (PRA: 2.8 vs 3.3, p=0.002; PAC: 8.7 vs 14.1, p<0.0001; PAC/PRA: 4.7 vs 5.4, p=0.172), and marginally higher systolic and diastolic BP percentiles (SBP%: 44.5 vs 40.6, p=0.082; DBP%: 57 vs 51, p=0.004). In blacks, the BP effect of PAC was much greater in blacks at lower PRA levels (p=0.004); in whites, PAC effect on BP was not significant (p=0.164) and the effect did not change noticeably with PRA. In conclusion, the finding supports the notion that blacks have higher levels of aldosterone sensitivity, especially for those with lower PRA. A sustained state of volume expansion appears to make blacks vulnerable to the BP effects of even small increments in sodium retention produced by aldosterone.
Abstract 371: DPPIV Inhibitor MK0626 Prevents Western Diet Induced Renal Injury via Suppression of Kidney Tissue Ras
Authors: Nistala Ravi , Habibi Javad , Aroor Annayya , Hayden Melvin R , Garro Mona , Meuth Alex , Johnson Megan , Irina Mugerfeld , Weidmeyer Charles , Adam Whaley-Connell , Sowers James R
Published: July 2021

Objectives:
Obesity is an independent risk factor for development and progression of renal injury. High fructose corn syrup consumption has coincided with the obesity epidemic in the United States. High fructose (60%) diets have been demonstrated to be associated with elevation in BP and worsening insulin resistance along with renal injury via increased hepatic production of uric acid. Recently, DPPIV inhibitors have been shown to improve diabetic changes and sodium excretion, effects that are beyond glycemic control. Therefore, the renal protective benefits of DPPIV inhibition in a clinically relevant Western diet fed mouse model were examined.

Methods:
Mice fed a high fat/high fructose (WD) diet for 16 weeks and given a DPPIV inhibitor MK0626 in their diet were examined for metabolic parameters, inflammation, kidney renin-angiotensin system (RAS) and oxidative stress. Renal injury was assessed by biochemical, immunohistological and electron microscopy techniques.
In vitro
, angiotensin II (Ang II) effects on OKP-PTCs were assessed for mechanism.

Results:
MK0626 ameliorated WD-induced increases in serum uric acid, oxidative stress and RAS. WD induced suppression of IL-10 was reversed by MK0626. There was a tendency to improve HOMA-IR by MK0626 but no effect on BP and body weights. Diet induced DPPIV activation in the plasma and kidney of WD mice was abrogated by MK0626 (~80%). WD mice were characterized by increased proteinuria (~3-fold), mesangial expansion and podocyte effacement and these changes were prevented by MK0626. In addition, the PTC endocytosis protein megalin and basilar canalicular network and mitochondrial ultrastructure abnormalities were reversed by MK0626. WD mice had decreased sodium excretion which was improved by MK0626. Ang II directly increased DPPIV activity and sodium hydrogen exchanger activity in PTCs and decreased megalin protein, which was effectively prevented by MK0626.

Conclusion:
Thus, WD induced increases in DPPIV activity is associated with elevations in uric acid, renal RAS, inflammation and oxidative stress which may result in renal injury. These results suggest that DPPIV inhibitors prevent WD induced renal injury and offer a novel therapy for diabetic and obesity associated renal disease.
Abstract 380: Short-term Treatment with Lercanidipine May Modulate Insuling Signalling and Oxidative Stress in Hypertensive Patients
Authors: Rossini Claudia , De Ciuceis Carolina , Flati Vincenzo , Rufo Anna , Porteri Enzo , Di Gregorio Jacopo , Petroboni Beatrice , La Boria Elisa , Sarkar Annamaria , Agabiti Rosei Claudia , Rizzoni Damiano , Agabiti Rosei Enrico
Published: July 2021

We investigated the effects of antihypertensive treatment with two drug combinations on insulin signalling and oxidative stress.

Twenty essential hypertensive patients were included in the study and treated for 4 weeks with lercanidipine orally. Then they were treated for 6 months with lercanidipine+enalapril (n=10) or lercanidipine+hydrochlorothiazide (n=10). Investigations were performed in basal condition, after 4 weeks of monotherapy with lercanidipine, and at the end of the combination treatment. Insulin signalling was evaluated in mononuclear cells by Wester-Blot. Circulating levels of C-reactive protein (CRP), proinflammatory cytokines interleukin-6 and interleukin-18 (IL-18), macrophage chemotactic factor-1 (MCP-1), soluble vascular cell adhesion molecule 1 and soluble inter-cellular adhesion molecule 1, malonyldialdehyde and lipid peroxidation were measured in plasma.

Results are summarized in the Table (*P<0.05, **p<0.01 vs. Basal; #p<0.05 vs. lercanipine alone). An increased expression of insulin receptor, GLUT-4 and an increased activation of p70S6K1 were observed during treatment with lercanidipine+enalapril but not with lercanidipine+hydrochlorothiazide. A reduction in circulating levels of IL 18, CRP and MCP-1 was observed after treatment with lercanidipine alone, which persisted or further improved after treatment with lercanidipine+enalapril but not with lercanidipine+hydrochlorothiazide.

Therefore the combination treatment lercanidipine+enalapril seems more effective than lercanidipine+hydrochlorothiazide in activating insulin signalling, possibly due to a more marked antioxidant/antiinflammatory effect.
Abstract 401: Ouabain-Digoxin Antagonism in Rat Arteries and Neurons: Acute Effects on Myogenic Tone and Neuronal Ca
2
+ Signaling
Authors: Song Hong , Karashima Eiji , Hamlyn John M , Blaustein Mordecai P
Published: July 2021

‘Classic’ cardiotonic steroids (CTS, e.g., digoxin and ouabain) selectively inhibit Na
+
,K
+
-ATPase (the Na
+
pump) and, via Na/Ca exchange, exert cardiotonic and vasotonic effects. CTS action is more complex than previously thought: Prolonged infusion of ouabain, but
not
digoxin, induces hypertension; in fact, digoxin antagonizes ouabain’s hypertensinogenic effect. We studied acute interactions between CTS in two indirect assays of Na
+
pump function: myogenic tone (MT) in isolated, pressurized rat mesenteric small arteries, and Ca
2+
signaling in primary cultured rat hippocampal neurons. The ‘classic’ CTS (0.3-10 nM) were ‘agonists’: they all increased MT
70
(MT at 70 mm Hg) and augmented 3-4 μM glutamate-evoked Ca
2+
(fura-2) signals. For example, 3-10 nM ouabain, digoxin and bufalin all increased myogenic constriction by 20-40% and neuronal Ca
2+
signals by 80-200%. We then tested one CTS in the presence of another. Most CTS were either ouabain-like (ouabagenin, dihydroouabain, strophanthidin) or digoxin-like CTS (digoxigenin, digitoxin, bufalin). Within each group, the CTS were synergistic, but ouabain-like and digoxin-like CTS antagonized one another in both assays. For example, 3 nM ouabain-evoked increases in MT
70
and neuronal Ca
2+
signals were both reversibly attenuated by 65-75% by adding 10 nM digoxin or 10 nM bufalin. Conversely, 3 nM digoxin- or bufalin-evoked increases in MT
70
and Ca
2+
signals were attenuated by 65-75% by 10 nM ouabain, but augmentation by bufalin was not antagonized by digoxin and vice-versa. Rostafuroxin (PST2238, 5 μM), a digoxigenin derivative that displaces
3
H-ouabain from Na
+
,K
+
-ATPase, and attenuates some forms of hypertension, antagonized ouabain's, but not digoxin's, effects. CTS bind to the α (catalytic) subunit of Na
+
pump αβ protomers in a 1:1 ratio. Analysis of potential models suggests that,
in vivo
, Na
+
pumps function as tetraprotomers [(αβ)
4
] in which the binding of a single CTS to one protomer blocks all pumping activity. The paradoxical ability of digoxin-like CTS to reactivate the ouabain-inhibited complex can be explained by de-oligomerization of the tetrameric state. The interactions between these common CTS may be of considerable therapeutic relevance.
Abstract 41: Fructose Stimulates Na/H Exchanger 3 Activity and Enhances the Ability of Angiotensin II to Activate Na/H Exchanger 3 in the Proximal Tubule
Authors: Cabral Pablo , Hong Nancy , Garvin Jeffrey
Published: July 2021

Consumption of high-fructose corn syrup as a sweetener has increased dramatically. Fructose has been implicated in the epidemic of diabetes, obesity and hypertension including salt-sensitive hypertension. However, the mechanisms are poorly understood. The proximal nephron reabsorbs 60-70% of the fluid and Na, and most of the filtered bicarbonate via Na/H exchanger 3. Enhanced proximal nephron transport has been implicated in several forms of hypertension. We hypothesized that fructose stimulates NHE3 activity and enhances the ability of angiotensin II (ANG II) to activate NHE3 in the proximal tubule. To test our hypothesis we isolated and perfused proximal tubules from Sprague Dawley rats. NHE3 activity was measured as the recovery of intracellular pH after an NH4Cl acid pulse using the pH sensitive dye BCECF. The rate of pH recovery was measured in Fluorescent Units per second (FU/sec). In the presence of a 5.5 mM glucose-containing physiological saline the basal rate of pH recovery was 3.1 ± 0.8 FU/sec. When the luminal solution was exchanged to a 0.6 mM glucose + 5 mM fructose-containing physiological saline in a second period, the rate of pH recovery increased to 5 ± 1 FU/sec (p<0.03, n=8).To study whether this effect was due to the addition of fructose or the removal of glucose to the lumen, we performed a separate set of experiments where 5 mM glucose was substituted for 5 mM fructose. In the presence of 0.6 mM glucose the basal rate of pH recovery was 3.6 ± 1.5 FU/sec. When 5 mM fructose was added the rate of pH recovery increased to 5.9 ± 2 FU/sec (p<0.02, n=5). Control experiments showed no differences between periods when 5 mm glucose was added back to the luminal perfusate. Finally, we tested the effect of low concentrations of ANG II in the presence or absence of luminal fructose. In the presence of 5.5 mM glucose, ANG II 10-12 M did not affect the rate of pH recovery (change: -1.1 ± 0.5 FU/sec, n=9). However, in the presence of 5 mM fructose, ANG II increased the rate of pH recovery (change: 4.0 ± 2.2 FU/sec, p< 0.03 n=6). We conclude that acute treatment with fructose stimulates NHE3 activity and enhances the ability of ANG II to activate NHE3 in the proximal tubule. These results may partially explain the mechanism by which a fructose diet induces hypertension.
Abstract 413: Renal Cyclooxygenase-2 Expression And Hemodynamic Role During Angiotensin II-dependent Hypertension
Authors: Gonzalez Alexis A , Green Torrance , Bourgeois Camille R , Luffman Christina , Prieto Minolfa C , Navar L. G
Published: July 2021

Intrarenal cyclooxygenase-2 (COX-2) activity is increased during activation of the renin-angiotensin-system (RAS) increasing synthesis of prostaglandin E2 (PGE2) and buffering the vasoconstrictor and antinatriuretic effects of angiotensin II (AngII). While AngII upregulates intrarenal COX-2 expression, it remains unclear if this occurs in a time-dependent manner, thereby impacting renal hemodynamics differently during the early and late phases of the development of high blood pressure in AngII-induced hypertension. Male Sprague-Dawley rats were infused with AngII (0.4 μg/min/kg). Systolic blood pressure (SBP), COX-2 expression and PGE2 tissue content and urinary excretion were evaluated at day 3, 7 and 14 of the AngII infusions. In acute studies we evaluated the effects of COX-2 inhibition at day 5-7 and day 14 on renal hemodynamic parameters. Chronic AngII infusions increased SBP from day 7 through 14: 162 ± 5 mmHg; and 198 ± 15 mmHg versus controls: 114 ± 10 mmHg; P<0.05. COX-2 mRNA and protein levels were high in kidney cortex only at day 3 (mRNA: 241 ± 56%, protein: 160 ± 21%, P<0.05 versus controls). Medullary COX-2 mRNA and protein were increased on days 3 (mRNA: 176 ± 20%, protein: 185 ± 32%, P<0.05 versus controls), 7 (mRNA: 189 ± 23%, protein: 158 ± 15%, P<0.05 versus controls) and 14 (mRNA: 148 ± 15%, protein: 135 ± 13%, P<0.05 versus controls). Urinary and medullary PGE2 increased by day 3 and remained elevated during days 7 and 14. COX-2 inhibition decreased GFR and renal blood flow in AngII infused rats during both the early and late phases. Interestingly, COX-2 inhibition decreased mean arterial blood pressure at day 14 of AngII-infusion (COX-2 inhibition: 124 ± 9 versus 140 ± 7 mmHg, P<0.05) but not during the early normotensive phase (COX-2 inhibition: 110 ± 4 versus 115± 4 mmHg, P=NS). These results indicate that enhanced medullary COX-2 expression and PGE2 production during both the early and late phases attenuates the effects of AngII on renal hemodynamics. However COX-2 inhibition at day 14 reduced blood pressure, suggesting that a vasoconstrictor COX-2 metabolite contributes to the hypertension during the late phase.
Abstract 435: The Integrity of Central Blood Pressure Regulation in Conscious Patients With Hypertension and Normal Healthy Control
Authors: Al-Rawas Sami F
Published: July 2021

Blood pressure (BP) is centrally regulated by baroreflex mechanism where a change in BP would provoke vagal and sympathetic responses to counteract the moment by moment perturbations in BP. This study investigated the integrity of central regulation of BP in patients with hypertension (HTN) in response to known and standard autonomic tests.

Beat-by-beat measurement of arterial BPs (mmHg);systolic, diastolic and mean (M), heart rate (HR) (beats/min) and indices of brainstem responses; cardiac vagal tone (CVT; arbitrary units) and cardiac sensitivity to baroreflex (CSB; ms/mmHg) were continuously monitored and recorded using the Neuroscope system (Medifit instruments Ltd, UK). Statistical analysis was performed using two tail student’s t test.

The study included total of 23 subjects; 12 hypertensive males (mean±SD; 45±14.4 years) and 11 (3 females, 8 males) controls (35.6±9.7 y). Their age difference was not significant. The table describes the cardiovascular and brainstem responses during: baseline, supine, before and to the following autonomic tests: deep breathing (DB), sitting up, standing up, isometric handgrip (IHG) and phase IIe of valsalva’s maneouvre (Val-IIe), in addition to P values for control subjects.

In conclusion, brainstem mechanism is intact in patients with HTN, however, there were variable responses during deep breathing and sitting up tests. The baseline measurement showed improper BP control and hence continuous measurement showed more reliability than office discrete readings to ensure effective BP monitoring. The adjustment of brainstem responses to antihypertensive therapy is suggested to be used as an index to monitor treatment effect.
Abstract 459: Vasoactivity of the Alzheimer ß-Amyloid Peptides is Mediated by an Activation of the a
1
-Adrenoreceptor
Authors: Haase Nadine , Herse Florian , Spallek Bastian , Haase Hannelore , Wallukat Gerd , Qadri Fatimunnisa , Szijártó István A , Rohm Ilonka , Yilmaz Atilla , Warrington Junie P , Gollasch Maik , Ryan Michael J , Müller Dominik N , Dechend Ralf
Published: July 2021

Alzheimer disease (AD) features β-amyloid peptide (Aβ) deposition in brain and blood vessels and is associated with hypertension. Aβ can cause vasoconstriction and endothelial dysfunction. Recently, we could show that Aβ peptides elicit a signal transduction pathway in vascular smooth muscle cells and cardiomyocytes, induced by α
1
-adrenergic receptor activation. We hypothesized that the Aβ vasoactivity is also induced by activation of the α
1
-adrenoreceptor. Mouse aortic Rings were incubated for 24 h with 1 μmol/l Aβ (25-35). The influence of Aβ (25-35) on vasoconstriction of mouse aortic rings was studied in the additional presence and absence of α
1
-adrenergic receptor blocker prazosin. Vasoactivity in isolated aortic rings was measured using an isometric myograph. Vasoconstriction to 5-hydroxytryptamine was significantly increased (P≤0.001) in aortic rings by Aβ (25-35) pretreatment. This vasoactive effect was improved by the presence of α
1
-adrenergic receptor blocker during the Aβ (25-35) pretreatment. Rat middle cerebral artery (MCA) segments were treated with either 0.1μmol/L Aβ (25-35) or 0.1μmol/L of a negative control peptide with a reverse amino acid sequence (Aβ rev.) of Aβ (25-35) for 4h. Constriction of the middle cerebral artery was measured in dual vessel chamber. Incubation with Aβ (25-35) significantly enhanced (P≤0.0005) response of middle cerebral artery segments to the α
1
-agonist phenylephrine induced contractions. In a further ex vivo model of Langendorff-perfused rat hearts Aβ (25-35) also induced vasoconstriction of coronary arteries that resulted in decreased coronary flow. These effects could also be reversed by α
1
-adrenergic receptor blockade. Furthermore we analyzed the brain of hypertensive dTGR animals and in human arteriosclerotic plaques for the presence of Aβ amyloid. Amyloid deposits are present in cerebral cortex of hypertensive dTGR animals with damaged blood-brain barrier and in human arteriosclerotic plaques. Our data are relevant to the association between AD and hypertension. They may serve to explain impaired of vascular responses by Aβ and could have therapeutic implications.
Abstract 46: FOXP3+ T Regulatory Lymphocytes Counteract Angiotensin II-Induced Vascular Injury
Authors: Mian Muhammad Oneeb Rehman , Barhoumi Tlili , Briet Marie , Ene Adriana Cristina , Rehman Asia , Paradis Pierre , Schiffrin Ernesto L
Published: July 2021

Introduction:
T lymphocytes participate in the low-grade inflammatory response that causes vascular injury in angiotensin (Ang) II-induced hypertension. Ang II-induced hypertension and endothelial dysfunction are blunted in T and B lymphocyte-deficient (

Rag1
-/-

) mice, and restored with reconstitution of T cells. However, the role of T regulatory lymphocytes (Treg) in Ang II-induced vascular injury is unclear. We hypothesized that adoptive transfer of FOXP3-deficient (Scurfy) T lymphocytes vs. wild-type (WT) cells will exacerbate Ang II-induced vascular damage in

Rag1
-/-

mice.

Methods:
Eleven-week old male

Rag1
-/-

mice were injected IV with PBS/2% FBS (control), 10
7
WT or Scurfy T lymphocytes, and 2 weeks later underwent sham surgery or were infused with Ang II (490 ng/kg/min, s.c.) using mini-osmotic pumps for 14 days (n=3-8). Systolic (SBP) and diastolic (DBP) blood pressure were measured by telemetry. Vascular function and structure were assessed in second order mesenteric arteries by pressurized myography. Reactive oxygen species (ROS) production and fibronectin and collagen I and III expression were determined in aorta.

Results:
Ang II induced a 40 mmHg SBP rise in

Rag1
-/-

mice for all treatment groups, but DBP rise was ~10 mmHg greater for WT and Scurfy T cell-injected mice than for control mice (
P
<0.01). Adoptive transfer of WT T cells restored Ang II induced-endothelial dysfunction in mesenteric arteries (
P
<0.05), which was exaggerated in Scurfy T cell-injected mice (
P
<0.01). Ang II induced a greater increase in ROS production in aortic perivascular fat of Scurfy T cell-injected mice compared to WT T cell-injected mice (
P
<0.05). Ang II induced mesenteric artery stiffness (
P
<0.01) and hypertrophic remodeling (
P
<0.05) in control and Scurfy T cell-injected mice, but not in WT T cell-injected mice. Ang II increased fibronectin expression to a greater extent in the aorta of control and Scurfy T cell-injected mice compared to WT T cell-injected mice (
P
<0.01). Collagen I and III content was greater in the aorta of control and Scurfy T cell-injected mice than in WT T cell-injected mice (
P
<0.01), but expression was unaltered by Ang II treatment.

Conclusion:
Foxp3+ T regulatory lymphocytes have a protective role against Ang II-induced vascular remodeling.
Abstract 461: Macrophage 12/15-lipoxygenase Controls the Development of Experimental Hypertension through PPAR?
Authors: Kriska Tamas , Cepura Cody , Gauthier Kathryn M , Campbell William B
Published: July 2021

Targeted disruption of the 12/15-lipoxygenase (Alox15) gene in mice prevents the development of angiotensin II-, DOCA-salt-, and L-NAME-induced experimental hypertension. Macrophages are the primary source of Alox15. Using Alox15-/- and wild type (WT) mice, we previously demonstrated that macrophage Alox15 is essential for experimental hypertension; however, the underlying mechanism is not known. Since Alox15-derived metabolites of arachidonic and linoleic acids are potent PPARγ agonists, we hypothesized that activation of macrophage PPARγ is the key step in Alox15 mediation of L-NAME-induced hypertension. Thioglycollate (TG) injection, used to elicit peritoneal macrophages, upregulated PPARγ protein expression and expression of its target gene CD36 in peritoneal macrophages, but not in aorta or kidney, of both WT (6.8±0.3 and 9.3±0.5 fold increase for PPARγ and CD36, respectively) and Alox15-/- mice (4.7±0.4 and 11.1±0.6 fold increase for PPARγ and CD36, respectively). Thus, TG bypassed Alox15 to activate PPARγ selectively in macrophages. Upregulation of PPARγ by TG restored the sensitivity to L-NAME hypertension (100 mg/kg/day L-NAME for 7 days) in Alox15-/- mice (129.4±7.3 mmHg for TG vs. 94.8±5.6 mmHg for non-injected controls, p<0.005). A similar hypertensive effect to L-NAME was observed with the adoptive transfer of TG-elicited Alox15-/- macrophages into Alox15-/- recipient mice (122.4±5.5 mmHg for macrophage vs. 96.2±6.2 mmHg for vehicle, p<0.05). The role of PPARγ was further specified by using the selective PPARγ antagonist, GW9662. When WT mice were treated with GW9662, 50 μg/kg/day for 12 days, L-NAME-induced hypertension did not develop (97.6±4.8 mmHg for GW9662 vs. 131.7±6.5 mmHg for vehicle, p<0.01). The PPARγ antagonist also prevented L-NAME-induced hypertension in TG-injected Alox15-/- mice, indicating a PPARγ-mediated effect in macrophages that results in hypertension. These results demonstrate that TG selectively upregulates macrophage PPARγ, bypassing the missing component in Alox15-/- macrophages, and permitting L-NAME-induced hypertension in Alox15-/- mice. Thus, the macrophage Alox15/PPARγ pathway is an important checkpoint in the development of L-NAME-induced hypertension.
Abstract 473: Compound-21 Acts at Renal Proximal Tubule AT2 Receptors to Inhibit Na+ Reabsorption via Bradykinin, Nitric Oxide, and Cyclic GMP
Authors: Kemp Brandon A , Howell Nancy L , Padia Shetal H , Carey Robert M
Published: July 2021

Angiotensin (Ang) AT2 receptors (AT2Rs) are expressed in the kidney at vascular and tubular sites. Previous studies from our lab have shown that renal AT2R activation induces natriuresis and that Ang III is the endogenous agonist for this response. Compound 21 (C21) is a highly selective non-peptide AT2R agonist with approx. 25,000-fold selectivity for AT2Rs over AT1 receptors (AT1Rs). However, C21, particularly at high concentrations, has recently been shown to have AT2R-independent effects in the vasculature. We hypothesized that C21 induces natriuresis via AT2R translocation to the apical membrane and by activating a bradykinin (BK)-nitric oxide (NO)-cyclic GMP (cGMP) signaling pathway in the renal proximal tubule (RPT). In anesthetized, uninephrectomized, volume-expanded rats, intravenous (iv) C21 infusion (100, 200 and 300 ng/kg/min; each dose for 30 min) increased urinary Na+ excretion (UNaV) from 0.16±0.03 to 1.12±0.19, 1.51±0.08 and 2.03±0.21 μmol/min, respectively; all P <0.001). This natriuretic response was not altered by 24 h subcutaneous infusion of AT1R antagonist candesartan (CAND; 0.01 mg/kg/min), but was abolished by renal interstitial (RI) infusion of specific AT2R antagonist PD-123319 (PD). Blood pressure was unaltered by C21 or PD, but was lower in CAND-infused rats (P <0.0001). C21 infusion increased fractional excretion of Na+ (FENa) from 0.36±0.07 to 0.90±0.18% (P<0.05) and lithium (FELi) from 30.2±3.3 to 57.2±5.2% (P <0.01) without altering glomerular filtration rate or renal blood flow. Compared to control, C21 infusion increased RPT cell apical membrane AT2R protein (0.11±0.006 vs. 0.08±0.004 DU respectively) without changing total cell AT2R. C21-induced natriuresis was also accompanied by an increase in RI cGMP from 3.78±0.82 to 17.1±3.39 pmol/ml (P<0.01). The C21-induced increases in both UNaV and RI cGMP were abolished by RI infusion of NO synthase inhibitor L-NAME or BK B2 receptor antagonist icatibant. The results demonstrate that C21 initiates AT2R translocation to the RPT cell apical membrane inducing natriuresis in a BK-NO-cGMP-dependent manner in the absence of concurrent AT1R blockade. C21 holds promise as a natriuretic/diuretic agent for the treatment of fluid retaining states and hypertension.
Abstract 477: Diverse Actions of the EP4 Prostaglandin E2 Receptor in Blood Pressure Control
Authors: Herrera Marcela , Sparks Matthew A , Koller Beverky H , Coffman Thomas M
Published: July 2021

Prostaglandin E2 (PGE2) is a major prostanoid produced by the kidney having the potential to influence renal blood flow, Na excretion, and thus mean arterial pressure (BP). PGE2 actions are mediated by four distinct E-prostanoid (EP) receptor isoforms: EP1-EP4. The EP4 receptor (EP4R) triggers macula densa stimulation of renin, induces vasodilation, and may inhibit epithelial sodium transport. Thus, the impact of EP4Rs on BP may differ with the sites of PGE2 synthesis and pattern of EP4R activation within the kidney. To examine the role of EP4R on BP regulation we generated EP4R-deficient mice. Because deletion of EP4R in utero causes peri-natal mortality due to persistent patent ductus arteriosus, we carried out conditional deletion by crossing EP4flox/flox with a transgenic line with tamoxifen-inducible Cre expression in all tissues. Resting mean arterial pressure (MAP) measured by radiotelemetry was increased by 5±1mm Hg (p<0.05) in mice with total-body EP4R-deficiency (EP4R-TBKO) vs. controls. In addition, EP4R-TBKOs had an exaggerated increase in MAP with high-salt (6% NaCl) feeding (MAP increase: 5±1 vs. 2±1mmHg for controls; p<0.05) and during angiotensin II (Ang II)-dependent hypertension (MAP increase: 37±2 vs. 24±3mmHg for controls; p<0.05). We next hypothesized that exaggerated hypertension in the EP4R-TBKOs was due to elimination of compensatory EP4R-depedent vasodilation mediated by direct actions in vascular smooth muscle cells (VSMCs). Accordingly, we generated mice lacking EP4R in VSMCs (EP4R-SMKOs) using EP4flox/flox and transgenic mice with tamoxifen-inducible expression of Cre limited to smooth muscle cells. In contrast to the EP4R-TBKOs, elimination of EP4R only from VSMC reduced resting MAP by 5±1mm Hg (p<0.04) but did not affect the BP response to high salt feeding (MAP change: 2±1 vs. 2±1 mm Hg; ns) or chronic Ang II infusion (MAP increase: 29±3 vs. 34±4 mm Hg; ns). Thus, the EP4R modulates resting MAP but its specific impact may vary between EP4R populations in different cell lineages. EP4Rs resist the development of salt- and Ang II-dependent hypertension. These anti-hypertensive actions are not mediated by direct effects of EP4R in VSMCs, but may involve EP4R in endothelium, brain, or kidney epithelia.
Abstract 479: Shortening of Mitochondria and Dilation of Endoplasmic Reticulum in the Medullary Thick Ascending Limb of Dahl Salt-Sensitive Rats
Authors: He Xiaofeng , Liang Mingyu
Published: July 2021

Functional abnormalities in the kidney appear to precede or coincide with the initiation of salt-induced hypertension in the Dahl salt-sensitive SS rat. However, the structural basis or mechanism of early renal abnormalities, especially in the renal tubules, is poorly understood. We performed electron microscopy analysis in 7 week old SS rats and salt-insensitive consomic SS.13
BN
rats and Sprague-Dawley (SD) rats fed a 4% NaCl diet for 7 days. Long mitochondria (>2 μm), an indication of healthy mitochondria, accounted for a significantly smaller fraction of all mitochondria in medullary thick ascending limbs in SS rats (4% ± 1%) than in SS.13
BN
rats (8% ± 1%, P<0.05 vs. SS) and SD rats (9% ± 1%, P<0.01 vs. SS). This is consistent with our previous findings of mitochondrial insufficiency in the medulla of SS rats. Long mitochondria in proximal tubules, however, were more abundant in SS rats than in SS.13
BN
and SD rats. The width of endoplasmic reticulum, an index of endoplasmic reticulum stress, was significantly greater in medullary thick ascending limbs of SS rats (107 ± 1 nm) than SS.13
BN
rats (95 ± 2 nm, P<0.001 vs. SS) and SD rats (74 ± 3 nm, P<0.01 vs. SS or SS.13
BN
). The rat strain differences in ultrastructure were observed even though the tubules were indistinguishable by light microscopy and less than 5% of the kidney area was affected by inflammation, interstitial fibrosis, or tubular casts. These data indicate that ultrastructural abnormalities in the mitochondria and endoplasmic reticulum in the medullary thick ascending limbs occur in the early stage of, and could contribute to, the development of salt-induced hypertension.
Abstract 485: Enhanced Large Conductance Ca+2 -sensitive K+ Channels (bk) Activity Impairs the Myogenic Response in the Cerebral Vasculature of Fawn Hooded Hypertensive (fhh) Rat
Authors: Pabbidi Mallikarjuna R , Farley Jerry , Gebremedhin Debebe , Harder David R. , Roman Richard J.
Published: July 2021

Our recent studies have revealed that the myogenic response in cerebral arteries and autoregulation of cerebral blood flow is impaired in FHH and that transfer of a 2.4 Mb region of chromosome 1 from BN into FHH.1
BN
congenic strain restores these responses. The present study examined the role of large conductance calcium activated potassium (BK) channel in altering the myogenic response in FHH rats. Whole-cell patch-clamp of cerebral vascular smooth muscle cells (VSMC) revealed a 4.6 fold increase in outward potassium (K) channel current densities (pA/pF) in FHH rats compared to FHH.1
BN
congenic strain. Iberiotoxin (IBTX -a selective BK channel inhibitor) sensitive current densities are significantly greater in FHH rats compared with the FHH.1
BN
congenic strain (FHH rats: +40mV; pre IBTX 43.1 ± 7.2, after IBTX 11.8 ± 2.2 pA/pF versus pre IBTX 5.6 ± 1 pA/pF and after IBTX 4.1 ± 0.6 pA/pF in the FHH.1
BN
congenic strain). In excised patches, the BK channel exhibited similar single-channel slope conductance for FHH and the FHH.1
BN
rats (208.9 pS versus 208.7 pS). However, the open channel probability (NP
o
) was ~10 fold higher in FHH rats than in FHH.1
BN
rats (1μM free (Ca
+2
)
i
: +40mV: FHH; 0.8 ± 0.04 versus 0.08 ± 0.004 in FHH.1
BN
rats). Voltage and Ca
2+
sensitivity of the BK channel is similar in cerebral VSMC isolated from FHH and FHH.1
BN
rats. Middle cerebral arterioles (MCA) isolated from FHH rats increased in diameter from 142 ± 16 to 157 ± 19 μm when pressure was increased from 40 to 140 mmHg. In contrast, the diameter of the MCA decreased by 49% in the FHH.1
BN
congenic strain from 127 ± 16 to 65 ± 13 μm. Pharmacological block of BK channel by IBTX (100nM) restored myogenic response in FHH rats but had no effect in FHH.1
BN
rats. These results indicate that the impaired myogenic response of the cerebral vessels in FHH rats is mediated via a gene and mechanism that enhances BK

channel activity.
Abstract 492: Circulating Hydrogen Sulfide is Stored as Labile Sulfurs in Albumin
Authors: Wesseling Sebastiaan , Abrahams Alferso C , Szabo Csaba , van Goor Harry , Joles Jaap A
Published: July 2021

Despite several methods to measure H
2
S, physiological H
2
S serum concentrations remain highly variable and method-dependent. While modifying the classic methylene blue (MB) method to improve detection of serum H
2
S levels, we also probed potential sulfur-binding characteristics of serum albumin.

To avoid loss of serum H
2
S and to trap sulfide ions effectively in the MB method serum was strongly alkalized to completely ionize gaseous H
2
S, followed by incubation with zinc acetate at 37°C, to trap sulfide ions effectively. After incubation, N,N-Diethyl-p-phenylenediamine and FeCl
3
were added to form MB product. Subsequently, trichloroacetic acid was added to remove matrix effects. Absorbance of MB product was at 670nm and compared to a dilution range of NaHS. Spectra (400-900nm) were taken to check quality of MB product and exclude matrix effects. Adaptations in experimental setup are mentioned below.

Applying the modified MB method produced the unexpected finding that yield of serum H
2
S increases with higher pH and longer incubation time. H
2
S synthesizing enzymes cystathionine-β-synthase and cystathionine -lyase were both ruled out as sources of serum H
2
S by separately treating serum with their respective inhibitors hydroxylamine and DL-propargylglycine. Human serum protein standard containing only albumin and -globulin, or pure bovine serum albumin (BSA), also yielded H
2
S. Albumin was confirmed as source of H
2
S by absence of increasing H
2
S yield from analbuminemic rat serum, as compared to normal rat serum. That yield of H
2
S increased at least twofold after treating both BSA and human serum with dithiolthreitol (DTT), a disulphide reducer, and close correlation between albumin level and yield of H
2
S during DTT incubation (r
2
=0.99), both suggest H
2
S storage in albumin as “labile sulphurs”.

The modified MB method allows measurement of release of H
2
S from albumin. Treating albumin with a disulphide reducer revealed H
2
S storage in albumin as sulfanes. Our work is consistent with suggestions that circulating 'pools' of biologically relevant sulfur/sulfide species exist. Thus, albumin may be a source of H
2
S, as has been observed for NO. How this is affected by disease states (e.g. chronic renal failure) remains to be seen.
Abstract 527: Obstructive Sleep Apnea and Endothelial Dysfunction in Resistant Hypertension
Authors: Amorim Nádia M , Bassan Fabiana B , Araújo Luciene d , Fernandes Julia F , Rodrigues Maria d , Valença Débora C , Marques Ruy G , Torres Márcia R , Sanjuliani Antonio F
Published: July 2021

Background:
Obstructive sleep apnea (OSA) is considered an independent risk factor for cardiovascular disease and reported as the most common secondary cause of high blood pressure (BP) maintenance.

Objective:
To determine the prevalence of OSA and verify its association with endothelial function behavior and anthropometric parameters in patients with resistant hypertension (RHGroup) and BP controlled by medication (CHGroup).

Methods:
Cross-sectional study involving 40 hypertensive patients (20 in RHG and 20 in CHG), aged between 18 and 75 years. Endothelial function and OSA were assessed by peripheral arterial tonometry. BP was measured by oscillometric method on automatic device. Endothelial function was assessed by peripheral arterial tonometry (PAT) by EndoPAT2000 and the OSA diagnosis also through PAT, using the portable device WatchPAT200. Anthropometric evaluation was performed through measurements of waist (WaC), hip and neck circumference (NC), BMI, waist to height ratio (WHtR), and body composition assessed by BIA.

Results:
The prevalence of OSA in RHG was 85% (17 of 20)[apnea-hypopnea index = 12.39±1.89], and 80% (16 of 20) in CHG (AHI=20.74±4.69) and it was more frequent in men (93.7% [15 of 16]
vs
75% [16 of 24]; p=0.0455,
OR
=3.86; 95% IC 0.99 to 5.09). Both groups presented similar anthropometric parameters values. Endothelial function evaluated by reactive hyperemia index was similar in both groups (RHG: 1.88±0.44
vs
CHG: 2.03±0.43; p=0.47). Although we found differences in oxygen desaturation> 4% (RHG: 28.75 ± 5.08
vs
CHG: 64.15 ± 16.97, p = 0.05), total sleep time (RHG: 307.2 ± 71.3
vs
CHG: 323.3 ± 83.8 min) and minimum saturation (RHG: 87.8±3.8
vs
CHG: 83.3±10.6%) was not different. In general, OSA was correlated with weight (r = 0.5135, p = 0.0007), BMI (r = 0.4146, p = 0.0078), WaC (r = 0, 4458, p = 0.005), NC (r = 0.3863, p = 0.01) and WHtR (r = 0.3907, p = 0.01) and independently associated with impairment of endothelial function (p = 0.0297, OR = 0.17, 95% CI 0.04 to 0.72).

Conclusions:
The findings of the present study show that the prevalence of OSA was similar in both groups and suggest that, in hypertensive subjects, OSA occurs more frequently in men, being associated with endothelial dysfunction and correlated positively with weight, BMI and WaC.