bluuebunny/crossref_metadata_2025 huggingface dataset:
MRI to Evaluate Left Atrial and Ventricular Reverse Remodeling After Restrictive Mitral Annuloplasty in Dilated Cardiomyopathy
Authors: Westenberg Jos J.M. , van der Geest Rob J. , Lamb Hildo J. , Versteegh Michel I.M. , Braun Jerry , Doornbos Joost , de Roos Albert , van der Wall Ernst E. , Dion Robert A.E. , Reiber Johan H.C. , Bax Jeroen J.
Published: July 2021

Background—

Data on reverse remodeling of the left atrium (LA) and left ventricle (LV) after restrictive annuloplasty in patients with dilated cardiomyopathy are scarce, and follow-up studies are performed with echocardiography.

Methods and Results—

Twenty patients with dilated cardiomyopathy and severe mitral regurgitation selected for restrictive mitral annuloplasty underwent serial MRI studies (within 1 week before surgery, and 2 months [n =18] and 1 year [n =13] after surgery). Early mortality was 10%; all patients were free from endocarditis and thromboembolism. New York Heart Association class improved from 3.2±0.4 to 1.2±0.9. Only 1 patient developed recurrent severe mitral regurgitation during follow-up and it was re-repaired. LA end-systolic volumes decreased significantly over time (from 165±48 mL to 109±23 mL to 111±28 mL;
P
<0.01), as did LA end-diastolic volumes (from 92±32 mL to 71±22 mL to 75±17 mL;
P
=0.01). LV end-diastolic volumes decreased significantly (from 244±56 mL to 184±54 mL to 195±67 mL;
P
<0.01), whereas end-systolic volumes did not change significantly. LV ejection fraction increased significantly (from 35±8% to 46±13% to 46±15%;
P
<0.01) and LV mass decreased significantly (from 150±43 grams to 132±39 grams to 136±33 grams;
P
=0.02).

Conclusion—

Restrictive annuloplasty in patients with dilated cardiomyopathy yielded excellent clinical results associated with significant LA and LV reverse remodeling over time as demonstrated by MRI.
High Mortality Associated With Precluded Coronary Artery Bypass Surgery Caused by Severe Distal Coronary Artery Disease
Authors: Cordeiro da Rocha Antônio Sérgio , Rodrigues Dassa Nella Paula , Monassa Pittella Felipe José , Barbosa Odilon Nogueira , Reis Brito José Oscar , Tura Bernardo , Dutra da Silva Paulo Roberto
Published: July 2021

Background—

Patients with extensive coronary artery disease (CAD) have better prognosis when treated with coronary artery bypass grafting surgery (CABG), especially when left ventricular dysfunction (LVD) is present. However, there are scanty data about the clinical course of patients not referred to CABG because of extensive and severe atherosclerotic involvement of distal coronary arteries (ENDCAD). The aim of this study was to evaluate patients with multivessel (MV) or left main CAD (LM) who had CABG precluded because of ENDCAD.

Methods and Results—

Between August 1999 and July 2001, 51 patients who had clinical indication but were not eligible for CABG because of ENDCAD were followed for at least 12 months or until death. There were 32 men and 19 women (age 61±9 years). Previous acute myocardial infarction (AMI) was present in 31 (60.8%), diabetes mellitus (DM) in 28 (54.9%), systemic arterial hypertension in 37 (72.5%), LVD (left ventricular ejection fraction <40%) in 26 (51%), 3 vessel CAD in 31 (60.8%), and LM in 4 (7.8%). During follow-up there were 20 cardiac (39.2%) deaths, 19 (37.2%) AMI, and 3 (5.8%) patients developed congestive heart failure. There were 2 (3.9%) noncardiac deaths. Patients with DM (60.7% versus 13%;
P
=0.001; odds ratio [OR], 10.30; 95% confidence interval [CI], 2.46 to 43.09), LVD (76.9% versus 0%;
P
<0.0001; OR, 4.33; 95% CI, 2.14 to 8.74), 3-vessel CAD (51.6% versus 20%;
P
=0.039; OR, 4.26; 95% CI, 1.16 to 15.69), and LM (100% versus 34%;
P
=0.019; OR, 1.25; 95% CI, 1.004 to 1.556) were more likely to die. There was no deaths in patients with 2-vessel CAD but they had more nonfatal AMI (43.8% versus 14.3%; OR, 4.667; 95% CI, 1.188 to 18.332).

Conclusions—

Patients in whom CABG could not be performed because of ENDCAD had high mortality, especially in the presence of LVD. DM (particularly insulin-dependent), LM CAD, and 3-vessel CAD were independent markers of increased risk.
Predictors of Low Cardiac Output Syndrome After Isolated Aortic Valve Surgery
Authors: Maganti Manjula D. , Rao Vivek , Borger Michael A. , Ivanov Joan , David Tirone E.
Published: July 2021

Background—

Low cardiac output syndrome (LCOS), defined as the need for postoperative intraaortic balloon pump or inotropic support for >30 minutes in the intensive care unit, remains a relatively common complication of aortic valve (AV) surgery. The aim of this study is to identify the preoperative predictors of LCOS in patients undergoing isolated AV surgery.

Methods and Results—

We conducted a retrospective review of data prospectively entered into an institutional database. Between 1990 and 2003, 2255 patients underwent isolated AV surgery with no other concomitant cardiac surgery. The independent predictors of LCOS and operative mortality (OM) were determined by stepwise logistic regression analysis. The overall prevalence of LCOS was 3.9%. The independent predictors of LCOS were (odds ratio in parentheses) renal failure (5.0), earlier year of operation (4.4), left ventricular ejection fraction <40% (3.6), shock (3.2), female gender (2.8), and increasing age (1.02). Overall OM was 2.9%. The OM was higher in patients who experienced LCOS (38% versus 1.5%;
P
<0.001). The independent predictors of mortality were (odds ratio in parentheses) preoperative renal failure (8.3), urgency of surgery (3.4), previous stroke (2.9), congestive heart failure (2.6), previous cardiac surgery (2.3), hypertension (1.7), and small AV size (1.3).

Conclusions—

Low-output syndrome is associated with significantly increased morbidity and mortality. Novel strategies to preserve renal function, optimization of preexisting heart failure symptoms, and avoidance of prosthesis-patient mismatch may reduce the incidence of LCOS and lead to improved results after AV surgery.
Novel Injectable Bioartificial Tissue Facilitates Targeted, Less Invasive, Large-Scale Tissue Restoration on the Beating Heart After Myocardial Injury
Authors: Kofidis Theo , Lebl Darren R. , Martinez Eliana C. , Hoyt Grant , Tanaka Masashi , Robbins Robert C.
Published: July 2021

Background—

Implantation of bioartificial patches distorts myocardial geometry, and functional improvement of the recipient heart is usually attributed to reactive angiogenesis around the graft. With the liquid bioartificial tissue compound used in this study, we achieved targeted large-scale support of the infarcted left ventricular wall and improvement of heart function.

Methods and Results—

A liquid compound consisting of growth factor-free Matrigel and 10
6
green fluorescent protein (GFP)-positive mouse (129sv) embryonic stem cells (ESCs) was generated and injected into the area of ischemia after ligation of the left anterior descending artery in BALB/c mice (group I). Left anterior descending artery-ligated mice (group II) and mice with Matrigel (group III) or ESC treatment alone (group IV) were used as the control groups (n=5 in all groups). The hearts were harvested for histology 2 weeks later after echocardiographic assessment with a 15-MHz probe. The liquid injectable tissue solidified at body temperature and retained the geometry of the infarcted lateral wall. Immunofluorescence stains revealed voluminous GFP grafts. The quality of restoration (graft/infarct area ratio) was 45.5±10.8% in group I and 29.1±6.7% in group IV (
P
=0.034). ESCs expressed connexin 43 at intercellular contact sites. The mice treated with the compound had a superior heart function compared with the controls (
P
<0.0001 by ANOVA/Bonferroni test; group I: 27.1±5.4, group II:11.9±2.4, group III:16.2±2.8, group IV: 19.1±2.7).

Conclusions—

Injectable bioartificial tissue restores the heart’s geometry and function in a targeted and nondistorting fashion. This new method paves the way for novel interventional approaches to myocardial repair, using both stem cells and matrices.
Effectiveness of the Maze Procedure Using Cooled-Tip Radiofrequency Ablation in Patients With Permanent Atrial Fibrillation and Rheumatic Mitral Valve Disease
Authors: Abreu Filho Carlos A.C. , Lisboa Luiz A.F. , Dallan Luís A.O. , Spina Guilherme Sobreira , Grinberg Max , Scanavacca Maurício , Sosa Eduardo A. , Ramires José Antonio F. , Oliveira Sérgio A.
Published: July 2021

Background—

Although the Cox-Maze III procedure is effective for treating permanent atrial fibrillation (AF), its high complexity limits its use. The Saline-Irrigated Cooled-tip Radiofrequency Ablation (SICTRA) System is an alternative source of energy used to ablate AF. The aim of this study was to evaluate the effectiveness of the SICTRA for the treatment of permanent AF in patients with rheumatic mitral valve (MV) disease.

Methods and Results—

Between February 2002 and April 2003, 70 patients with permanent AF and rheumatic MV disease were randomly assigned to undergo a modified Maze III procedure using SICTRA associated with MV surgery (group A) or MV surgery alone (group B). Groups A and B were similar in terms of baseline characteristics. The in-hospital mortality rate was 2.3% (1 death) in group A versus 0% (no deaths) in group B (
P
>0.99). The additional time required for the left-sided radiofrequency ablation in group A was 14.2±5.1 minutes and for right-sided ablation was 12.3±4.2 minutes. The mean postoperative follow-up periods were 13.8±3.4 and 11.5±7.3 months, respectively, in groups A and B. The overall mid-term survival rate was 95.1% in group A and 92.8% in group B (
P
>0.99). The cumulative rates of sinus rhythm were 79.4% in group A and 26.9% in group B (
P
=0.001). Doppler echocardiography documented biatrial transport function in 90.3% of group A patients in sinus rhythm.

Conclusions—

The SICTRA is effective for treating permanent AF associated with rheumatic MV disease.
Endothelin-a Receptor Blockade Attenuates the Hypertension in a Rat Model of Pregnancy-Induced Hypertension.
Authors: Alexander Barbara T , Rinewalt Anna N , Massey Matthew B , Bennett William M , Granger Joey P
Published: July 2021

6

A rat model of pregnancy-induced hypertension (PIH) produced by chronic reductions in uterine perfusion pressure (RUPP) is associated with a significant elevation in mean arterial pressure and as previously reported by our laboratory, proteinuria and reductions in kidney function. The purpose of this study was to examine the role of endothelin in mediating the hypertension in response to chronic reductions in uterine perfusion pressure in conscious, chronically-instrumented pregnant rats. Mean arterial pressure in RUPP rats (n=7) was significantly higher (123.0 ± 0.8 vs 101.3 ± 1.5 mmHg) than control pregnant rats (n=8). Renal expression of preproendothelin was also significantly elevated (>45%, P<.05) in the medulla (44.1 ± 6.3 vs 24.0 ± 2.6 densitometric units, respectively) and in the cortex (>20%, 37.7 ± 2.4 vs 29.9 ± 2.8 densitometric units, respectively) of the RUPP animals as compared to normal pregnant animals. Chronic administration of the selective endothelin-A receptor antagonist (ABT-627, 5mg/kg/day for 10 days, n=9) markedly attenuated the increase in MAP observed in the RUPP animals (123.0 ± 0.8 mmHg in the RUPP animals vs. 103.3 ± 2.3 mmHg in RUPP animals with ET-A antagonist, P<.05). Endothelin-A receptor blockade had no significant effect on blood pressure in the normal pregnant animals (101.3 ± 1.5 mmHg in normal pregnant rats vs. 96.0 ± 0.9 mmHg in normal pregnant animals with ET-A antagonist, n=8). In summary, hypertension in the RUPP model of pregnancy-induced hypertension was associated with enhanced renal expression of preproendothelin. In addition, hypertension in the RUPP model of PIH was significantly attenuated by selective endothelin-A receptor blockade. These findings suggest that endothelin plays a major role in mediating the hypertension observed in this animal model of pregnancy-induced hypertension produced by chronic reductions in uterine perfusion pressure.
Angiotensin II Induces Human Monocyte Migration and Pyk2/ Paxillin Phosphorylation
Authors: Kintscher Ulrich , Wakino Shu , Kim Sarah , Fleck Eckart , Hsueh Willa A , Law Ronald E
Published: July 2021

12

Angiotensin II (AII) has been shown to enhance the development of atherosclerotic lesions. Transendothelial migration of monocytes is an early critical step in the atherosclerotic process. To elucidate mechanisms by which AII promotes atherogenesis, we investigated its effects on human monocyte migration. AII induced migration of human peripheral blood monocytes (HPBM) and human THP-1 monocytes at concentrations between 0.01-1μmol/L, with 3.3-fold induction in HPBM and 4.8-fold in THP-1cells at 1μmol/L AII (both p< 0.01 vs. unstimulated cells). To identify cell signalling pathways involved in AII-directed migration, we blocked extracellular regulated protein kinase (ERK1/2) - MAPK activation with PD98059 (PD) and p38-MAPK activity with SB203580 (SB). Pretreatment of HPBM with PD (30μmol/L) and SB (10μmol/L) blocked AII (1μmol/L) stimulated migration by 75.6 +/- 3.1% (p< 0.01) and 52.8 +/- 2.6% (p< 0.01), respectively. AII (1μmol/L) directed migration of THP-1 monocytes was inhibited by 67.7 +/- 15.9% (PD 30μmol/L, p< 0.01) and 47.2 +/- 12.3% (SB 10μmol/L, p<0.05). Addition of the AII receptor type 1 (AT1R) antagonist Losartan (LOS) completely supressed AII induced monocyte migration, demonstrating an AT1R mediated mechanism (HPBM: LOS 100μmol/L 83.1 +/- 6.5% inhibition (p< 0.05)/ THP-1: LOS 100μmol/L 91.3+/- 21.5% inhibition (p<0.01)). Cell movement requires the phosphorylation of cytoskeleton-associated tyrosine kinases and formation of focal adhesion complexes. Western immunblotting with phosphospecific antibodies showed that AII (1μmol/L) induced the rapid tyrosine phosphorylation of PYK2 , a calcium-dependent tyrosine kinase, in THP-1 cells by 3.6-fold peaking after 10min. Phosphorylation of the focal adhesion related protein paxillin was enhanced in THP-1 cells by AII (1μmol/L) with a 4.3-fold induction after 2 min. This study demonstrates a potential proatherogenic mechanism of AII by stimulating human monocyte migration through an AT1R-ERK1/2-p38-dependent process, which might be, in part, mediated by AII induced PYK2/Paxillin phosphorylation.
Brain-Selective Expression of Exogenous Angiotensin (AT1) Receptors Causes Enhanced Cardiovascular Sensitivity.
Authors: Lazartigues Eric , Dunlay Shannon M , Sinnayah Puspha , Sigmund Curt D , Davisson Robin L
Published: July 2021

19

To examine the functional consequences of overexpression of AT1 receptors selectively in brain of both normal mice and in mice otherwise lacking endogenous AT1 receptors, we generated a novel transgenic model with AT1 receptors targeted selectively to neurons in the CNS. A fusion transgene consisting of 2.8 Kb of rat neuron-specific enolase(NSE) 5’ flanking region, and a cDNA encoding the full open reading frame of the AT1A receptor was constructed and transgenic mice (NSE-AT1) were generated. Of the six transgenic founder lines identified, two exhibited overexpression of the transgene selectively in brain. Using both immunohistochemistry and a high affinity fluorescently labeled angiotensin II (AngII) probe, we observed high levels of transgenic AT1A receptors in brain of both lines. Distribution of the receptors was particularly prominent in regions involved in cardiovascular regulation, including brainstem and lamina terminalis nuclei. Focusing on NSE-AT1 line 6085/2, direct recording of baseline blood pressure in conscious freely moving mice revealed no difference between transgenic and wildtype controls. However, intracerebroventricular injection of AngII (50, 100, 200 ng, 200 nL) in conscious NSE-AT1 mice (n=5) caused an increased pressor response (Δ17±2, 22±4, 33±5) and a profoundly enhanced bradycardia (Δ-48±6, -92±27, -114±17) compared to wildtypes (n=8) (BP: Δ7±2, 17±2, 21±1; HR: Δ-15±12, -23±7, -34±10). Our data show that brain-selective overexpression of exogenous AT1 receptors results in enhanced cardiovascular sensitivity to central AngII. This model, along with a model harboring this transgene but lacking AT1 receptors elsewhere (NSE-AT1 mice bred with AT1 knockouts), provide a new approach and important tools for identifying the cardiovascular regulatory roles of brain AT1 receptors relative to those in peripheral tissues.
P2x
1
Receptor Blockade Inhibits Pressure-Induced Afferent Arteriolar Autoregulatory Behavior.
Authors: Inscho Edward W , Cook Anthony K
Published: July 2021

26

P2X
1
receptors are heavily expressed along the preglomerular vasculature but not on efferent arterioles. P2 receptor activation has been implicated in mediating afferent arteriolar (AA) autoregulatory behavior; however, the receptor subtype responsible remains unknown. This study was performed to test the hypothesis that selective blockade of P2X
1
receptors with the novel P2X
1
receptor antagonist, NF-279, will inhibit pressure-mediated AA autoregulatory responses. Kidneys from enalaprilat treated (2mg, iv), anesthetized rats were prepared for videomicroscopy experiments using the
in vitro
blood perfused juxtamedullary nephron technique. Autoregulatory behavior was assessed in response to step increases in perfusion pressure (PP) from 100mmHg to 130 and 160mmHg while AA diameter was continuously monitored. Autoregulatory responses were measured under control (Con) conditions and during P2X
1
receptor blockade with NF-279. Time controls have verified that duplicate autoregulatory maneuvers yield similar decreases in AA diameter. During the control period, AA diameter decreased significantly from 20.8 ± 0.8 to 17.3 ± 0.5 (83% of Con) and 14.7 ± 0.7μm (71% of Con) at PP of 100, 130 and 160mmHg, respectively (P<0.05; n=5). During the ensuing recovery period, AA diameter returned to control values (20.6 ± 1.2μm). After the recovery period, 20μM NF-279 was administered via the superfusate. In the presence of NF-279, AA diameter remained stable at 20.6 ± 1.3μm during perfusion at 100mmHg and did not change when PP was increased. AA diameter averaged 20.5 ± 1.3 (98% of Con) and 20.3 ± 1.2μm (97% of Con) at PP of 130 and 160mmHg, respectively. NF-279 abolished the sustained AA response to the P2X
1
agonist, α, β-methylene ATP (1μM; P<0.05; n=5), but did not alter the AA response to the A
1
receptor agonist, cyclopentyl adenosine (1nM; n=6) or to 1nM Ang II (n=4). These data support our previous observations implicating ATP-induced P2 receptor activation in mediating AA autoregulatory behavior. More importantly, these data provide new and compelling evidence identifying the P2X
1
receptor as the specific receptor subtype responsible for AA autoregulatory behavior.
Amelioration of Angiotensin Ii-Induced Cardiac Injury by Hmg-Coa Reductase Inhibition
Authors: Dechend Ralf , Fiebeler Anette , Park Joon-Keun , Muller Dominik N , Theuer Jurgen , Mervaala Eero Ma , Bieringer Markus , Schmidt Folke , Gulba Dietrich , Dietz Rainer , Luft Friedrich C
Published: July 2021

32

HMG-CoA reductase inhibitors have effects that extend beyond cholesterol reduction. We used an angiotensin (Ang) II-dependent model to test the hypothesis that cerivastatin ameliorates cardiac injury. We treated rats transgenic for human renin and angiotensinogen (dTGR) chronically from week 4 to 7 with cerivastatin (0.5 mg/kg/d by gavage). We used immunohistochemistry, electrophoretic mobility shift assays, and RT-PCR techniques. Compared to control dTGR, dTGR treated with cerivastatin had reduced mortality, blood pressure, cardiac hypertrophy, macrophage infiltration, and collagen I and IV deposition. Total plasma cholesterol was not different between the groups. Immunohistochemical analysis showed increased expression of basic fibroblast growth factor (b-FGF), IL-6, and the NF-κB subunit p65 in the media of dTGR, which was markedly reduced by cerivastatin. b-FGF mRNA in the left ventricle was also significantly reduced. The transcription factors NF-κB and AP-1 were substantially less activated in the left ventricle. These results suggest that statins ameliorate Ang II-induced hypertension, cardiac hypertrophy, and remodeling, independent of cholesterol reduction. They suggest that statins interfere with Ang II-induced signaling and transcription factor activation, thereby ameliorating end-organ damage.
The Relationship Between Angiotensin II (ANG II) and Oxidative Stress in the Maintenance of Mean Arterial Pressure (MAP) of Spontaneously Hypertensive Rats.
Authors: Bolterman Rodney J , Ortiz-Ruiz Clara M , Juncos Luis A , Reckelhoff Jane F , Romero Juan C
Published: July 2021

48

Spontaneously hypertensive rats (SHR) reportedly have inappropriately high levels of Ang II despite normal plasma renin activity (PRA). Because Ang II stimulates oxidative stress, which in turn quenches nitric oxide, it is possible that Ang II-induced increases in oxidative stress contribute to the increase in blood pressure. Indeed, administering either a converting enzyme inhibitor (to decrease Ang II) or Tempol (a potent antioxidant) reduces blood pressure in SHR. We tested whether decreasing Ang II with a converting enzyme inhibitor reduces oxidative stress as well as MAP in SHR. For this, we divided 12 weeks old SHR into two groups (n=5 each). One group was treated with captopril (100 mg/kg/day added to the drinking water) and the other served as our untreated time controls. After 16 days of treatment, the rats were anesthetised and we measured MAP and collected blood samples to determine PRA, and the plasma levels of Ang II and thiobarbituric acid-reactive substances (TBARS). The captopril-treated rats had a lower MAP than the untreated rats (92±4 vs. 160±5 mmHg, respectively) and an increased PRA (42±1 vs. 26±6 ng/ml/h; captopril-treated vs. untreated rats, respectively). The decreased MAP in the captopril-treated SHR was accompanied by reduced plasma levels of Ang II (630±47 vs. 836±205 pg/ml) and TBARS (5.4±1.0 vs. 3.0±0.2 nmol/ml). Despite the significant decrease in Ang II levels in the captopril-treated SHR, they are still 20-fold higher rhan in normotensive Sprague-Dawley rats (34.0±8.8 pg/ml). In summary, captopril-induced decreases of MAP in SHR are accompanied not only by reduced levels of Ang II, but also by reduced oxidative stress. Because antioxidants also lower MAP in SHR, it suggests that oxidative stress induced by Ang II may play a role in the pathogenesis of the increased blood pressure in SHR.
Microarray Analysis of Gene Expression in the Renal Inner Medulla of the Dahl Salt-Resistant and Salt-Sensitive Rat
Authors: Jackson Robert W , Pollock David M , Stoming Terry R , Pollock Jennifer S
Published: July 2021

49

The inner medulla contains several mechanisms that play a central role in fluid-volume homeostasis. We hypothesized that transcriptional regulation of the inner medulla in response to a high sodium diet differs between the Dahl salt-resistant (SR) and salt-sensitive (SS) rats. SR and SS (16 wk) were placed on either a 0.5% (low) or 4.0% (high) NaCl diet. After 5 weeks, total RNA from the renal inner medulla was isolated from two rats in each of the following groups: SR/low, SR/high, SS/low, and SS/high. Labeled cRNA was hybridized to microarrays representing 7000 genes (Affymetrix). In response to increased Na intake in the SR rat, 46 genes were up-regulated and 7 genes down-regulated (>2-fold changes). This adaptive response included the up-regulation of guanylin (3-fold;3X), cytochrome P
450
(8X), cyclooxygenase-2 (3X), kidney-specific androgen-regulated protein (8X) and the down regulation of Tamm-Horsfall protein (-39X). In contrast, high salt in SS rats revealed the differential expression of only one gene, the up-regulation of guanylin (3X). To investigate the general absence of a transcriptional response in SS rats, we found that, 23 genes were expressed at higher levels and 14 at lower levels in SS/low compared to SR/low. Interestingly, 7 of 23 genes that were elevated in the SS/low, were the same genes that were up-regulated in the SR/high. Thus, components of the adaptive response to high Na in SR rats are operating in SS rats prior to a Na challenge. Ten genes were increased and four were decreased in the SS/high when compared to the SR/high. The ROMK K
+
channel (3X), Na-K-2Cl cotransporter (6X), and an ATPase inhibitor (8X) were expressed at higher levels in the SS/high. A majority of the other genes not mentioned have not been studied in the context of sodium handling or hypertension. These findings reveal clear differences in the basal gene expression within the inner medulla between SR and SS rats. Furthermore, these results show that salt-sensitivity is associated with a diminished transcriptional response to a high salt diet which supports the hypothesis that this region of the kidney contributes to genetic salt-sensitive hypertension.
Transgenic Rescue of Defective Cd36 Attenuates Insulin Resistance, Dyslipidemia, and Hypertension in Spontaneously Hypertensive Rats
Authors: Pravenec Michal , Landa Vladimir , Zidek Vaclav , Kren Vladimir , Kazdova Ludmila , Qi Nianning , Wang Jiaming , St. Lezin Elizabeth , Kurtz Theodore W
Published: July 2021

70

Linkage studies in spontaneously hypertensive rats (SHR) have implicated a host of different DNA sequence variants in the genetic control of blood pressure (BP) and a variety of other cardiovascular phenotypes. However, direct proof that any of these gene variants represents a true quantitative trait locus (QTL) regulating BP or any other complex trait is lacking. To directly test the identity of putative QTL in the SHR model, we have: 1) developed transgenic techniques for rescuing mutant alleles directly on the SHR background and 2) used these techniques to determine whether a gene encoding a fatty acid transporter (Cd36) truly represents a QTL that can influence the clustering of multiple cardiovascular risk factors in spontaneous hypertension. Towards these ends, we have successfully derived multiple transgenic strains of SHR (SHR-TG strains) that express the wild type allele for Cd36 on an SHR background harboring the deletion variant of Cd36 (SHR control). In these strains, low level expression of wild type Cd36 on the mutant SHR background ameliorated glucose intolerance (e.g., area under the GTT curve = 713±21 in the SHR-TG19 strain vs. 954±45 mmol/L/2hr in the SHR control strain, p<.001), insulin resistance (e.g., insulin stimulated glucose uptake in muscle = 355±104 in the SHR-TG19 strain vs. 135±13 nmol/g/2 hrs in the SHR control strain, p<.01), and dyslipidemia (e.g., fatty acid levels = 276±27 in the SHR-TG19 strain vs. 389±42 μmol/L in the SHR control strain, p<.05). Similar results were observed in the SHR-TG10 strain. In addition, in the SHR-TG19 strain, transgenic expression of wild type Cd36 in the kidney was associated with significant reductions in BP (p<.005 by radiotelemetry). These findings: 1) demonstrate that transgenic SHR can be derived to directly test the identity of putative QTL for complex cardiovascular traits; 2) establish that defective Cd36 is a bona fide QTL that can influence the clustering of multiple cardiovascular risk factors in spontaneous hypertension, and 3)should motivate further studies on the role of Cd36 in the regulation of BP, renal function, and the pathogenesis of hypertension.
Targeting Gene Transfer Selectively to Vascular Endothelial Cells Using Peptides Isolated by Phage Display: Implications for Development of Gene Therapy in Hypertension
Authors: Nicklin Stuart A , White Steve J , Baker Andrew H
Published: July 2021

75

Current gene transfer vectors are extremely limited for selective vascular cell delivery due to their promiscuous tropism and low efficiency of gene delivery to the vasculature. We have sought to improve the efficiency of gene transfer to vascular endothelial cells using phage display. Using bio-panning on whole cells, we have isolated a panel of 60 7-mer peptides that have the ability to bind endothelial cells but not to non-endothelial cells including vascular smooth muscle cells and hepatocytes. One candidate peptide was cloned upstream of a single chain antibody (scFv) generated against the knob domain of adenovirus type 5, expressed in bacteria and purified. While the scFv alone inhibited adenoviral fiber-dependent infection of all cell types tested (to >95% in hepatocytes), the scFv-peptide fusion mediated selective infection into endothelial cells without infection into non-endothelial cells types. Furthermore, the level of infection achieved in endothelial cells was 15 fold higher than that achieved with fiber-mediated gene transfer alone. We have additionally isolated 15 individual peptides that have the ability to target the endothelial leptin-like oxidised LDL receptor (LOX-1), a receptor highly expressed in endothelial cells in hypertensive models and in atherosclerotic lesions, by phage bio-panning on cells ectopically expressing the LOX-1 receptor. Candidate peptides mediated significantly higher binding to LOX-1 expressing cells compared to LOX-1 negative cells. Their ability to re-target adenoviral gene transfer is being tested. Our results demonstrate that small, novel peptides isolated by phage display have the ability to retarget gene transfer selectively and efficiently to vascular endothelial cells. This has important implications for targeting gene transfer to endothelial cells for molecular and therapeutic protocols in hypertension.
Cardiomyocytes Bind and Activate Renal But not Non-Renal Human Prorenin.
Authors: Saris Jasper J , Derkx Frans HM , Saxena Pramod R , Lamers Jos MJ , Schalekamp Maarten ADH , Danser Alexander HJ
Published: July 2021

P10

Cardiomyocytes bind and internalize recombinant human prorenin (rhPR) and renin via mannose 6-phosphate (M6P) receptors (van Kesteren et al., Hypertension 1997). PR binding is followed by intracellular activation. Here we investigated 1) whether cardiomyocytes bind native human (pro)renin ((P)R) from various sources and 2) whether PR binding is followed by activation. Myocytes were isolated from Wistar rat pups by enzymatic dissociation and grown to confluence (6 x 10
5
cells in 3.8 cm
2
wells). Cells were incubated with rhPR, human plasma (obtained from captopril-treated patients (CAP), patients with renal artery stenosis (RAS) and anephric subjects (Nx)), or human amniotic fluid (HAF), diluted in DMEM (final volume 0.4 mL), for 4 hrs at 37°C, either with or without 10 mM M6P. Cell-associated R and PR, the latter following prior activation by plasmin, were determined by enzyme-kinetic assay. Results: See Table. Intracellular PR activation is reflected by the higher R/PR ratio in the cell lysates as compared to the medium. Conclusions: Cardiomyocytes bind and activate native human PR from renal (CAP & RAS), but not from non-renal (Nx & HAF) sources in a M6P- dependent manner. These data suggest that renal PR is meant to be sequestered by nonrenin-producing tissues in order to contribute to local angiotensin production, whereas non-renal PR functions at its production site only.
Endogenous Metabolites of Estradiol Inhibit Endothelin Synthesis by Coronary Artery Endothelial Cells Via Estrogen Receptor (ER) Indepedent Mechanism
Authors: Dubey Raghvendra K , Rosselli Marinella , Keller Paul J , Imthurn Bruno
Published: July 2021

P26

Estradiol (E) inhibits endothelin (ET) synthesis via estrogen receptor (ER)-dependent pathway and this may,in part, mediate the protective effects of E against coronary artery disease (CAD)in postmenopausal women. However, recent findings that E inhibits neointima formation in mice lacking α and β ER, suggests that the protective effects of E may be mediated via an ER independent mechanism. Because endogenous metabolites of E (2-hydroxyestradiol [2OHE] and 2-methoxyestradiol [2MeOE]) with little/no affinity for ERs, are more potent than E in inhibiting SMC growth, we investigated whether these metabolites also inhibit ET synthesis via an ER-independent mechanism. Treatment of porcine coronary artery endothelial cells (ECs)for 12-48 hrs with .001-1μM of 2OHE or 2MeOE concentration-dependently inhibited basal as well as TNFα (10ng/ml) and thrombin (.1U/ml) stimulated ET synthesis and these effects were not blocked in presence of ER-antagonist ICI182780 (50μM; ICI). The effects of 2OHE and 2MeOE on ET synthesis was also mimicked by various clinically used estrogens (E valerate, E cypionate, ethinyl E) which are metabolized in vivo and by cultured cells. Our finding that 2OHE and 2MeOE inhibit basal and stimulated ET synthesis suggests that endogenous metabolism of E to 2OHE and 2MeOE may mediate the anti-vasoocclusive effects of E via an ER-independent mechanism. Moreover, endogenous metabolism of E to 2OHE and 2MeOE may be responsible for the decreased incidence of CAD in premenopausal women. In conclusion, both ER-dependent and -independent mechansims may mediate the endogenous effects of E on ET synthesis.
Nerve Growth Factor Enhances Calcitonin Gene-Related Peptide Expression in the Spontaneously Hypertensive Rat
Authors: Huawei Zhao M , Scott C Supowit M , Donald J DiPette M
Published: July 2021

P45

We previously reported that there is a marked decrease in neuronal (dorsal root ganglia [DRG] sensory neurons) CGRP expression in the SHR compared to WKY controls. This reduction in such a potent vasodilator could contribute to the elevated BP. We hypothesize that administration of NGF, a potent in vivo stimulator of CGRP expression, to SHR would decrease the BP. NGF (10 nM/kg/day, i.p.) was given to 12 week SHR (n=8-11/group) once a day for 1, 3, and 7 days. Control SHR received vehicle only. All rats were instrumented for CGRP receptor antagonist (CGRP
8-37
) administration (i.v.) and continuous MAP (arterial) recording and were studied in a concious and unrestrained state. Both the 1 and 3 day NGF treatments lowered the MAP (147±5 and 147±3 mmHg; respectively, p<0.05) compared to the controls (166±3 mmHg). However, by day 7 the MAP had returned to control levels (169±5 mmHg). To determine whether CGRP was involved in the BP lowering response to NGF, saline or CGRP
8-37
(bolus dose of 200 μg) were administered i.v. to all rats. Saline was without effect in any of the groups studied. In contrast, CGRP
8-37
administration produced a significant increase in MAP in both the 1 (13±1 mmHg) and 3 (10±1 mmHg) day NGF treatment groups. Surprisingly, in the 7 day treatment group, CGRP
8-37
also increased the MAP (13±2 mmHg) despite the baseline BP being back up to control levels. Quantification of CGRP mRNA and peptide levels in DRG revealed a significant (p<0.05) 1.5-fold increase on days 1 and 3 and a 1.75-fold increase on day 7. These data demonstrate that NGF treatment of SHR can significantly increase neuronal CGRP expression. At days 1 and 3, NGF produces a marked depressor response that is primarily due to CGRP as evidenced by the pressor effect of CGRP
8-37
. In the day 7 group, CGRP also plays a counterregulatory role even though the MAP has returned to control levels. This may result from an NGF-mediated upregulation of a pressor system that counteracts the hypotensive actions of CGRP. These results, therefore, suggest that the decreased production of CGRP in the SHR could contribute to the elevated BP observed in this hypertensive model.
At
2
Receptor-Mediated Vasodilation in the Heart: Effect of Myocardial Infarction.
Authors: Schuijt Martin P , Basdew Munesh , van Veghel Richard , Saxena Pramod R , Schoemaker Regien G , Danser Alexander HJ
Published: July 2021

P64

To investigate the functional consequences of the changes in AT
2
receptor density that have been reported following myocardial infarction (MI; Matsubara, Circ Res, 1998), three consecutive 10 min intravenous infusions of angiotensin (Ang) II (100, 300 and 1000 ng/kg/min) were given to 19 sham-operated and 16 coronary artery-ligated rats, at four weeks after surgery, pretreated with either saline, the AT
1
receptor antagonist irbesartan (100 μg/kg/min for 30 min), or the AT
2
receptor antagonist
PD123319
(20 μg/kg/min for 30 min, followed by continuous infusion). Systemic and regional hemodynamic effects were studied using the radioactive microsphere method. Ang II induced comparable changes in sham and MI rats in mean arterial pressure (MAP; maximally +30±10% and +30±8%, resp., mean±SEM) and systemic vascular conductance (cardiac output/MAP, -27±8% and -32±5%, resp.). Cardiac output decreased in MI (-20±5%) but not in sham rats. Irbesartan decreased MAP by 34% (sham) and 22% (MI), increased SVC by 41% (sham) and 24% (MI), and blocked the Ang II-mediated systemic hemodynamic effects in both sham and MI rats, while
PD123319
did not affect these parameters. Myocardial conductance at baseline was diminished in MI vs. sham rats (41±3 vs. 55±6 μl/min/mmHg, resp.), while renal conductance was comparable in both groups (168±9 vs. 156±18 μl/min/mmHg, resp.). Ang II increased myocardial conductance maximally to 56±3 (MI) and 72±3 (sham) μl/min/mmHg, and decreased renal conductance to 67±4 (MI) and 74±8 (sham) μl/min/mmHg. Irbesartan increased renal, but not myocardial, conductance in both groups and blocked the Ang II-mediated renal vasoconstriction.
PD123319
did not affect renal or myocardial conductance and blocked the Ang II-mediated myocardial vasodilation in sham but not in MI rats.
PD123319
did not affect the Ang II-mediated renal responses. In conclusion, Ang II increases myocardial, but not renal, conductance (i.e., induces vasodilation) via AT
2
receptor stimulation. The inability of
PD123319
to block this response in MI rats suggests either an upregulation of AT
2
receptors or a role for non-AT
1
, non-AT
2
receptors in the infarcted heart.
Effect of Troglitazone on Blood Pressure, Glut Expression, Glucose Uptake and Reactivity of Vascular Smooth Muscle in Doca/Salt Hypertension.
Authors: Atkins Kevin Brady , Webb R. Clinton , Brosius Frank C
Published: July 2021

P73

We previously demonstrated that glucose transporter (GLUT4) expression was reduced in aorta and carotid arteries of DOCA/salt hypertensive rats. Although this model of hypertension is not insulin resistant, we hypothesized that the insulin sensitizer, troglitazone (TG), stabilizes GLUT expression possibly through maintenance of the differentiated phenotype. DOCA/salt rats and shams were fed either standard chow or ground chow with TG at the rate of 100 mg/rat/day for 4 weeks post-surgery. While there was no difference in blood pressure between the two sham groups, there was a significant (p≤0.009), decrease in systolic BP in the DOCA/TG (157.2±5.66 mmHg) compared to the DOCA/salt (202.2±10.34 mmHg) treated rats. Immunoblotting of extracts of carotid arteries demonstrated that GLUT4 expression was significantly decreased with DOCA/salt and that this was reversed by TG. Decreased GLUT4 with DOCA/salt is specific to vascular tissue since there was no effect in heart. Both the expression and activity (phospho-specific antibody) of Akt/PKB were increased in DOCA/TG carotid arteries compared to DOCA/salt. There was decreased 2-deoxyglucose (2-DOG) uptake in aorta of DOCA/salt rats and this returned to control level in DOCA/TG aorta. We previously showed that DOCA/salt carotid strips exhibited increased agonist stimulated contractility. 2-DOG increased the contractility of sham strips, but had no further effect on DOCA/salt strips. Contractility of DOCA/TG strips is now being compared to DOCA/salt strips. TG (5μM), IGFI (2ng/mL) or the combined treatment of a human fetal-derived vascular smooth muscle cell line for 48-144h demonstrated an increased glucose transporter expression and a parallel increase in Akt expression. Since Akt/PKB is associated with a differentiated phenotype these combined data suggest that the effect of TG on GLUT levels partially may be mediated via increased Akt expression/activity and may explain the salutary effects of TG on BP.
Activation of Na
+
/Ca
2+
Exchanger in Kinin B
1
Receptor-Stimulated Human Fibroblast Is Associated with Collagen Production
Authors: Romero Jose R , Ricupero Dennis A , Rivera Alicia , Goldstein Ronald H , Conlin Paul R
Published: July 2021

P148

The arterial wall in hypertension is characterized by thickening of the media, in part due to increased deposition of connective tissue. Autocrine and paracrine factors may participate in this process; including products of the kallikrein-kinin system. We evaluated early signal transduction events and effects on collagen formation in B
1
-stimulated human myofibroblast cells (IMR-90). We measured cytosolic calcium (Ca
cyt
) levels in cells loaded with FURA-2AM. Gene expression of connective tissue growth factor (CTGF) and α1(I) collagen was determined by estimating mRNA levels using Northern analysis of B
1
stimulated cells. Activation of the B
1
receptor with des-arg
10
-kallidin stimulated a three-fold increase in CTGF mRNA by increasing its stability. Furthermore, B
1
receptor activation caused an increase in α1(I) collagen mRNA and a four-fold increase in type I collagen synthesis in these cells; events not observed in B
2
receptor-stimulated cells. Activation of the B
1
receptor stimulated a dose dependent rise in Ca
cyt
(EC
50
=1.9nM) which was completely inhibited by des-arg
10
-[leu
9
]-kallidin (100nM), a B
1
receptor antagonist. Isosmotic replacement of extracellular Na
+
with
N
-methyl,D-glucamine blocked > 90% of the B
1
stimulated rise in Ca
cyt
. A similar effect was observed when Ca
2+
was removed from the extracellular media, suggesting a role for the plasma membrane Na
+
/Ca
2+
exchanger (NCX). To further define a role for the NCX on CTGF formation we used dichlorobenzamil (DCB) and KB-R7943, two specific NCX inhibitors. DCB completely blocked the activation of B
1
receptor induced increase in CTGF mRNA stability while not affecting basal CTGF mRNA levels. In contrast, preincubation with EIPA, an amiloride analog, did not affect basal or stimulated CTGF mRNA levels. Furthermore, 60μM KB-R7943 blocked the B
1
stimulated rise in Ca
cyt
. NCX isoform 1 was identified in these cells using RT-PCR and immuno-detection. Thus, B
1
receptor stimulation increases fibrogenesis through a mechanism that involves modulation of cation metabolism
via
reverse-mode activation of NCX.
NO Inhibits Nacl Absorption by Rat Thick Ascending Limb Through Activation of Cgmp-Stimulated Phosphodiesterase.
Authors: Ortiz Pablo A , Garvin Jeffrey L
Published: July 2021

P96

NO regulates salt balance by inhibiting NaCl reabsorption along the nephron. In the isolated, perfused rat thick ascending limb (THAL), adding arginine to the bath stimulates endogenous NO production which inhibits NaCl absorption. While we reported the NO-signaling pathway in collecting ducts, it has not been studied in THALs. We hypothesized that endogenous NO inhibits NaCl transport by increasing cGMP production which in turn activates cGMP dependent protein kinase (PKG). THALs from rats were isolated and perfused, and net chloride flux (
J
Cl
-
) was measured. L-arginine (0.5 mM) added to the bath decreased
J
Cl
-
from 154.4±9.9 to 101.9±14.1 a 35.2% decrease (
n
=7;
p
< 0.05). Next we tested the effect of the soluble guanylate gyclase (sGC) inhibitor LY-83583 on L-Arg induced inhibition of
J
Cl
-
. In the presence of 10 μM LY-83583 adding L-Arg to the bath did not affect THAL
J
Cl
-
(143.7±28.1 vs. 136.7±22.2 pmol mm
-1
min
-1
;
n
=6). 10 μM LY-83583 alone did not affect THAL
J
Cl
-
(
n
=4). We then tested whether the cGMP-stimulated phosphodiesterase (PDE II) inhibitor EHNA blocked the effects of L-Arg. In the presence of 50 μM EHNA, L-Arg reduced chloride flux by only 11% (146.2±7.3 vs. 129.1±6.8 pmol mm
-1
min
-1
;
p
< 0.06;
n
=5). 50 μM EHNA alone did not change THAL
J
Cl
-
(
n
=4). Since cGMP activates PKG as well as PDE II, we tested whether the PKG inhibitor KT-5823 could prevent the L-Arg effect. In the presence of 2 μM KT-5823, L-Arg decreased
J
Cl
-
from 132.5±14.1 to 91.1±8.8 pmol mm
-1
min
-1
, an inhibition of 31% (
n
=9;
p
< 0.05). To determine whether all of the effects of L-arg are mediated by cGMP, we tested its effect on THAL
J
Cl
-
in the presence of cGMP. In the presence of 50 μM dibutyryl-cGMP,
J
Cl
-
was 116.3±9.7 pmol mm
-1
min
-1
. After L-Arg was added to the bath,
J
Cl
-
was 100.7±8.3 pmol mm
-1
min
-1
(
n.s
;
n
=5). We concluded that: 1) NO reduces THAL
J
Cl
-
by activating sGC, increasing cGMP and stimulating PDE II which likely decreases cAMP; 2) activation of PKG is not necessary for NO to decrease
J
Cl
-
; 3) the cascade activated by NO in the THAL is different from that activated in the collecting duct.
Renal HETA/ETB Receptor Disbalance Characterizes Progression to Salt Sensitive Malignant Hypertension in Spontaneous Hypertension
Authors: Rothermund Lars , Luckert Susanne , Kossmehl Peter , Neumayer Hans H , Paul Martin , Kreutz Reinhold
Published: July 2021

P99

It is unclear why a subgroup of patients with essential hypertension develop salt sensitive hypertension with progression to malignant hypertension and renal failure. We evaluated the role of the renal endothelin (ET)-system in this setting by investigating two animal models with either salt-resistant or salt sensitive spontaneous hypertension. We studied salt resistant spontaneously hypertensive rats (SHR) and salt sensitive stroke-prone spontaneously hypertensive rats (SHRSP) after either sham operation on a normal diet (Sham) or after unilateral nephrectomy and high NaCl loading (NX-NaCl) with 4% NaCl in diet for 6 weeks (n=10, respectively). Systolic blood pressure (SBP) increased only in SHRSP-NX-NaCl compared to SHRSP-Sham (250±6 vs. 172±5 mmHg, p<0.0001) while SBP remained unchanged in SHR-NX-NaCl compared to SHR-Sham. Albuminuria increased 210-fold in SHRSP-NX-NaCl compared to SHRSP-Sham (p<0.0001), but no significant change was observed in SHR-NX-NaCl. In SHRSP-NX-NaCl glomerulosclerosis index, tubulointerstitial damage index, renal ET-1 mRNA expression, and urinary ET-1 excretion were significantly elevated compared to SHRSP (p<0.05, respectively), but no significant changes of these parameters were found in SHR after NX-NaCl. Urinary sodium excretion (U
Na
) increased in both SHR and SHRSP after NX-NaCl, but U
Na
was significantly reduced by 60% in SHRSP-NX-NaCl compared to SHR-NX-NaCl (p<0.0001). After NX-NaCl renal ETA and ETB receptor densities, obtained by Scatchard analyses, were elevated in both SHR and SHRSP (ETA: 2.2- and 4.7-fold, ETB: 2.2- and 2.4-fold, p<0.05 respectively). However, ETA increase was significantly more pronounced in SHRSP-NX-NaCl, thus resulting in an 2.1-fold increase of ETA/ETB receptor ratio in SHRSP-NX-NaCl. We conclude that activation of the renal ET system in conjunction with an increased ETA/ETB receptor ratio may contribute to decreased U
Na
and higher susceptibility for the development malignant hypertension and kidney damage in salt sensitive spontaneous hypertension.