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Special Issue "Animal Models for Study of Pathophysiological Mechanisms of Hypertension and Its Complications"

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A special issue of Biomedicines (ISSN 2227-9059). This special issue belongs to the section "Molecular and Translational Medicine".

Deadline for manuscript submissions: closed (31 August 2022) | Viewed by 16300

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Special Issue Editors

Dr. Josef Zicha

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Guest Editor

Department of Experimental Hypertension, Institute of Physiology of the Academy of Sciences of the Czech Republic, Prague, Czech Republic
Interests: hemodynamics; vascular sensitivity and reactivity; cell calcium handling; ion transport

Dr. Ivana Vaněčková

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Guest Editor

Department of Experimental Hypertension, Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic
Interests: renin-angiotensin system; endothelin system; gliflozins; chronic kidney disease

Special Issue Information

Dear Colleagues,

Since essential hypertension is part of many important health care problems, it is necessary to investigate its mechanisms in animal models. This type of experimental research may have potential clinical importance. This Special Issue will be focused on several important topics, including:

1) The pathophysiological mechanisms responsible for:

i) Blood pressure elevation during hypertension development and maintenance;

ii) Organ damage in chronic hypertension;

iii) Drug targeting of hypertension and its complications.

2) The participation of:

i) Central and peripheral blood pressure control;

ii) Vascular hypertrophy and endothelial damage;

iii) Neural, humoral, and endocrine factors;

iv) Immune mechanisms.

3) The role of:

i) Altered redox signaling;

ii) Chronic inflammation;

iii) Microbiome changes;

iv) Genetic and/or environmental factors.

4) The progress in:

i) Pharmacological tools for the control of hypertension and organ damage;

ii) Genetic modifications to alter blood pressure level;

iii) Non-pharmacological interventions attenuating hypertension and its complications.

Original articles or reviews might also cover a) interesting aspects of particular research fields in the pathophysiology of hypertension and that are associated end-organ damage, b) the use of various experimental hypertensive models, and c) the importance of specific environmental factors acting in different phases of the ontogeny of hypertension. The presentation of new ideas as well as the critical discussion of traditional theories is also welcome.

Dr. Josef Zicha
Dr. Ivana Vaněčková
Guest Editors

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Keywords

genetic hypertension
salt hypertension
nutrition
antihypertensive therapy
renin-angiotensin-aldosterone system
sympathetic tone
nitric oxide
vascular resistance
oxidative stress
kidney damage

Published Papers (17 papers)

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Research

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Open AccessArticle

How Do Young and Old Spontaneously Hypertensive Rats Respond to Antihypertensive Therapy? Comparative Studies on the Effects of Combined Captopril and Nifedipine Treatment

Beate Rassler

Christina Hawlitschek

Julia Brendel

and

Heinz-Gerd Zimmer

Biomedicines 2022, 10(12), 3059; https://doi.org/10.3390/biomedicines10123059 - 28 Nov 2022

Cited by 1 | Viewed by 483

Abstract

Numerous studies on the effects of antihypertensive treatment in young spontaneously hypertensive rats (SHRs) have shown that early-onset therapy may effectively reduce their blood pressure (BP) even to normotensive values. In contrast, only a few studies investigated the effects of treatment started at an advanced age. These studies revealed that antihypertensive effects are lower in adult or even in senescent SHRs compared with young SHRs. Even more, prevention of cardiac sequelae of hypertension such as hypertrophy and fibrosis is less effective when treatment starts late in life. Because, in patients, combination therapies with calcium antagonists are favored, we studied the efficacy of a combination therapy with captopril and nifedipine in young and old SHRs. We directly compared the treatment effects on BP as well as on cardiac hypertrophy and remodeling between these two animal cohorts. With antihypertensive treatment, significantly lower BP values were achieved in young SHRs despite a shorter treatment period compared with old SHRs. Although treatment effects on cardiac hypertrophy were greater in old than in young SHRs, cardiac fibrosis was significantly attenuated only in young but not in old SHRs. The results emphasize the value of antihypertensive therapy and particularly accentuate the importance of an early-onset therapy. With respect to problems such as late diagnosis and poor therapy adherence, these results may have great importance for the treatment of human hypertension. Full article

(This article belongs to the Special Issue Animal Models for Study of Pathophysiological Mechanisms of Hypertension and Its Complications)

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Open AccessArticle

Stroke-Prone SHR as Experimental Models for Cardiovascular Disease Risk Reduction in Humans

and

Biomedicines 2022, 10(11), 2974; https://doi.org/10.3390/biomedicines10112974 - 18 Nov 2022

Viewed by 641

Abstract

Since stroke-prone spontaneously hypertensive rats (SHRSP) develop hypertension and stroke without exception, the prevention or reduction of risk by various nutrients was tested on blood pressure and the mortality caused by stroke and cardiovascular diseases (CVD). In addition to sodium (Na) accelerating hypertension and stroke and potassium (K) counteracting the adverse effect of Na, taurine (Tau), rich in seafood, and magnesium (Mg) contained in soy, nuts, grains, etc., were proven to reduce stroke and CVD and improved survival. Therefore, the Cardiovascular Diseases and Alimentary Comparison Study was started in 1985 to explore the association of biomarkers of diet in 24 h urine(24U) with CVD risks, and about 100 males and 100 females aged 48–56 in each of 50 populations were studied until 1995. Linear regression analysis indicated that the 24U Tau/creatinine and Mg/creatinine ratios were inversely associated with body mass index, systolic and diastolic blood pressure, and total cholesterol. In comparison with six Euro-Western regions, 24U Tau and Mg collected from six regions, respectively, in Japan and the Mediterranean countries were significantly higher and were significantly associated with lower CVD risks. Diets rich in Tau and Mg were concluded to be contributory to the prevention of CVD in SHRSP and humans. Full article

(This article belongs to the Special Issue Animal Models for Study of Pathophysiological Mechanisms of Hypertension and Its Complications)

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Open AccessArticle

Angiotensin II Modulates Calcium/Phosphate Excretion in Experimental Model of Hypertension: Focus on Bone

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Biomedicines 2022, 10(11), 2928; https://doi.org/10.3390/biomedicines10112928 - 14 Nov 2022

Cited by 1 | Viewed by 601

Abstract

A link between hypertension and long-term bone health has been suggested. The aim of this study was to investigate the effects of chronic angiotensin II administration on urinary calcium/phosphate excretion, bone mineral density, bone remodeling and osteoblast population in a well-established experimental model of hypertension, in the absence of possible confounding factors that could affect bone metabolism. Male Sprague–Dawley rats, divided in the following groups: (a) Angiotensin II (Ang II, 200 ng/kg/min, osmotic minipumps, sub cutis, n = 8); (b) Ang II+losartan (Los, 50 mg/kg/day, per os, n = 6); (c) control group (physiological saline, sub cutis, n = 9); and (d) control+losartan (n = 6) were treated for four weeks. During the experimental period, 24-hour diuresis, urinary calcium, phosphate and sodium excretion were measured prior to the treatment, at two weeks of treatment, and at the end of the treatment. Systolic blood pressure was measured by plethysmography technique (tail cuff method). At the end of the experimental protocol, the rats were euthanized and peripheral quantitative computed tomography at the proximal metaphysis and at the diaphysis of the tibiae and quantitative bone histomorphometry on distal femora were performed. Angiotensin II-dependent hypertension is associated with increased calcium and phosphate excretion. AT1 receptor blockade prevented the increase of blood pressure and phosphate excretion but did not affect the increase of calcium excretion. These changes took place without significantly affecting bone density, bone histology or osteoblast population. In conclusion, in our experimental conditions, angiotensin II-dependent hypertension gave rise to an increased urinary excretion of calcium and phosphate without affecting bone density. Full article

(This article belongs to the Special Issue Animal Models for Study of Pathophysiological Mechanisms of Hypertension and Its Complications)

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Open AccessArticle

Long-Term Excessive Dietary Phosphate Intake Increases Arterial Blood Pressure, Activates the Renin–Angiotensin–Aldosterone System, and Stimulates Sympathetic Tone in Mice

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Biomedicines 2022, 10(10), 2510; https://doi.org/10.3390/biomedicines10102510 - 07 Oct 2022

Viewed by 1077

Abstract

Increased dietary phosphate intake has been associated with severity of coronary artery disease, increased carotid intima–media thickness, left ventricular hypertrophy (LVH), and increased cardiovascular mortality and morbidity in individuals with normal renal function as well as in patients suffering from chronic kidney disease. However, the underlying mechanisms are still unclear. To further elucidate the cardiovascular sequelae of long-term elevated phosphate intake, we maintained male C57BL/6 mice on a calcium, phosphate, and lactose-enriched diet (CPD, 2% Ca, 1.25% P, 20% lactose) after weaning them for 14 months and compared them with age-matched male mice fed a normal mouse diet (ND, 1.0% Ca, 0.7% P). Notably, the CPD has a balanced calcium/phosphate ratio, allowing the effects of elevated dietary phosphate intake largely independent of changes in parathyroid hormone (PTH) to be investigated. In agreement with the rationale of this experiment, mice maintained on CPD for 14 months were characterized by unchanged serum PTH but showed elevated concentrations of circulating intact fibroblast growth factor-23 (FGF23) compared with mice on ND. Cardiovascular phenotyping did not provide evidence for LVH, as evidenced by unchanged LV chamber size, normal cardiomyocyte area, lack of fibrosis, and unchanged molecular markers of hypertrophy (Bnp) between the two groups. However, intra-arterial catheterization revealed increases in systolic pressure, mean arterial pressure, and pulse pressure in mice fed the CPD. Interestingly, chronically elevated dietary phosphate intake stimulated the renin–angiotensin–aldosterone system (RAAS) as evidenced by increased urinary aldosterone in animals fed the CPD, relative to the ND controls. Furthermore, the catecholamines epinephrine, norepinephrine, and dopamine as well as the catecholamine metabolites metanephrine. normetanephrine and methoxytyramine as measured by mass spectrometry were elevated in the urine of mice on CPD, relative to mice on the ND. These changes were partially reversed by switching 14-month-old mice on CPD back to ND for 2 weeks. In conclusion, our data suggest that excess dietary phosphate induces a rise in blood pressure independent of secondary hyperparathyroidism, and that this effect may be mediated through activation of the RAAS and stimulation of the sympathetic tone. Full article

(This article belongs to the Special Issue Animal Models for Study of Pathophysiological Mechanisms of Hypertension and Its Complications)

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Open AccessArticle

Empagliflozin Is Not Renoprotective in Non-Diabetic Rat Models of Chronic Kidney Disease

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Biomedicines 2022, 10(10), 2509; https://doi.org/10.3390/biomedicines10102509 - 07 Oct 2022

Viewed by 860

Abstract

Gliflozins (sodium-glucose transporter-2 inhibitors) exhibited renoprotective effects not only in diabetic but also in non-diabetic patients with chronic kidney disease (CKD). Controversial results were reported in experimental non-diabetic models of CKD. Therefore, we examined empagliflozin effects in three CKD models, namely, in fawn-hooded hypertensive (FHH) rats, uninephrectomized salt-loaded (UNX + HS) rats, and in rats with Goldblatt hypertension (two-kidney, one-clip 2K1C) that were either untreated or treated with empagliflozin (10 mg/kg/day) for eight weeks. Plethysmography blood pressure (BP) was recorded weekly, and renal parameters (proteinuria, plasma urea, creatinine clearance, and sodium excretion) were analyzed three times during the experiment. At the end of the study, blood pressure was also measured directly. Markers of oxidative stress (TBARS) and inflammation (MCP-1) were analyzed in kidney and plasma, respectively. Body weight and visceral adiposity were reduced by empagliflozin in FHH rats, without a significant effect on BP. Experimentally induced CKD (UNX + HS and 2K1C) was associated with a substantial increase in BP and relative heart and kidney weights. Empagliflozin influenced neither visceral adiposity nor BP in these two models. Although empagliflozin increased sodium excretion, suggesting effective SGLT-2 inhibition, it did not affect diuresis in any experimental model. Unexpectedly, empagliflozin did not provide renoprotection because proteinuria, plasma urea, and plasma creatinine were not lowered by empagliflozin treatment in all three CKD models. In line with these results, empagliflozin treatment did not decrease TBARS or MCP-1 levels in either model. In conclusion, empagliflozin did not provide the expected beneficial effects on kidney function in experimental models of CKD. Full article

(This article belongs to the Special Issue Animal Models for Study of Pathophysiological Mechanisms of Hypertension and Its Complications)

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Open AccessArticle

Slower Growth during Lactation Rescues Early Cardiovascular and Adipose Tissue Hypertrophy Induced by Fetal Undernutrition in Rats

Pilar Rodríguez-Rodríguez

Ignacio Monedero-Cobeta

David Ramiro-Cortijo

Sophida Puthong

Begoña Quintana-Villamandos

and

Biomedicines 2022, 10(10), 2504; https://doi.org/10.3390/biomedicines10102504 - 07 Oct 2022

Viewed by 767

Abstract

Low birth weight (LBW) and accelerated growth during lactation are associated with cardiometabolic disease development. LBW offspring from rats exposed to undernutrition during gestation (MUN) develops hypertension. In this rat model, we tested if slower postnatal growth improves early cardiometabolic alterations. MUN dams were fed ad libitum during gestation days 1–10, with 50% of the daily intake during days 11–21 and ad libitum during lactation. Control dams were always fed ad libitum. Pups were maintained with their own mother or cross-fostered. Body weight and length were recorded weekly, and breastmilk was obtained. At weaning, the heart was evaluated by echocardiography, and aorta structure and adipocytes in white perivascular fat were studied by confocal microscopy (size, % beige-adipocytes by Mitotracker staining). Breastmilk protein and fat content were not significantly different between groups. Compared to controls, MUN males significantly accelerated body weight gain during the exclusive lactation period (days 1–14) while females accelerated during the last week; length growth was slower in MUN rats from both sexes. By weaning, MUN males, but not females, showed reduced diastolic function and hypertrophy in the heart, aorta, and adipocytes; the percentage of beige-type adipocytes was smaller in MUN males and females. Fostering MUN offspring on control dams significantly reduced weight gain rate, cardiovascular, and fat hypertrophy, increasing beige-adipocyte proportion. Control offspring nursed by MUN mothers reduced body growth gain, without cardiovascular modifications. In conclusion, slower growth during lactation can rescue early cardiovascular alterations induced by fetal undernutrition. Exclusive lactation was a key period, despite no modifications in breastmilk macronutrients, suggesting the role of bioactive components. Our data support that lactation is a key period to counteract cardiometabolic disease programming in LBW and a potential intervention window for the mother. Full article

(This article belongs to the Special Issue Animal Models for Study of Pathophysiological Mechanisms of Hypertension and Its Complications)

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Open AccessArticle

Disparate Roles of Oxidative Stress in Rostral Ventrolateral Medulla in Age-Dependent Susceptibility to Hypertension Induced by Systemic l-NAME Treatment in Rats

Yung-Mei Chao

Hana Rauchová

and

Julie Y. H. Chan

Biomedicines 2022, 10(9), 2232; https://doi.org/10.3390/biomedicines10092232 - 08 Sep 2022

Cited by 1 | Viewed by 768

Abstract

This study aims to investigate whether tissue oxidative stress in the rostral ventrolateral medulla (RVLM), where sympathetic premotor neurons reside, plays an active role in age-dependent susceptibility to hypertension in response to nitric oxide (NO) deficiency induced by systemic l-NAME treatment, and to decipher the underlying molecular mechanisms. Systolic blood pressure (SBP) and heart rate (HR) in conscious rats were recorded, along with measurements of plasma and RVLM level of NO and reactive oxygen species (ROS), and expression of mRNA and protein involved in ROS production and clearance, in both young and adult rats subjected to intraperitoneal (i.p.) infusion of l-NAME. Pharmacological treatments were administered by oral gavage or intracisternal infusion. Gene silencing of target mRNA was made by bilateral microinjection into RVLM of lentivirus that encodes a short hairpin RNA (shRNA) to knock down gene expression of NADPH oxidase activator 1 (Noxa1). We found that i.p. infusion of l-NAME resulted in increases in SBP, sympathetic neurogenic vasomotor activity, and plasma norepinephrine levels in an age-dependent manner. Systemic l-NAME also evoked oxidative stress in RVLM of adult, but not young rats, accompanied by augmented enzyme activity of NADPH oxidase and reduced mitochondrial electron transport enzyme activities. Treatment with L-arginine via oral gavage or infusion into the cistern magna (i.c.), but not i.c. tempol or mitoQ₁₀, significantly offset the l-NAME-induced hypertension in young rats. On the other hand, all treatments appreciably reduced l-NAME-induced hypertension in adult rats. The mRNA microarray analysis revealed that four genes involved in ROS production and clearance were differentially expressed in RVLM in an age-related manner. Of them, Noxa1, and GPx2 were upregulated and Duox2 and Ucp3 were downregulated. Systemic l-NAME treatment caused greater upregulation of Noxa1, but not Ucp3, mRNA expression in RVLM of adult rats. Gene silencing of Noxa1 in RVLM effectively alleviated oxidative stress and protected adult rats against l-NAME-induced hypertension. These data together suggest that hypertension induced by systemic l-NAME treatment in young rats is mediated primarily by NO deficiency that occurs both in vascular smooth muscle cells and RVLM. On the other hand, enhanced augmentation of oxidative stress in RVLM may contribute to the heightened susceptibility of adult rats to hypertension induced by systemic l-NAME treatment. Full article

(This article belongs to the Special Issue Animal Models for Study of Pathophysiological Mechanisms of Hypertension and Its Complications)

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Open AccessArticle

Beneficial Effects of Empagliflozin Are Mediated by Reduced Renal Inflammation and Oxidative Stress in Spontaneously Hypertensive Rats Expressing Human C-Reactive Protein

and

Biomedicines 2022, 10(9), 2066; https://doi.org/10.3390/biomedicines10092066 - 24 Aug 2022

Cited by 5 | Viewed by 991

Abstract

Gliflozins (inhibitors of sodium-glucose cotransporter 2) show many beneficial actions beyond their antidiabetic effects. The underlying mechanisms of these additional protective effects are still not well understood, especially under non-diabetic conditions. Therefore, we analyzed the effects of empagliflozin in young (3-month-old) and adult (12-month-old) male spontaneously hypertensive rats (SHR) expressing human C-reactive protein (CRP) in the liver. SHR-CRP rats are a non-diabetic model of metabolic syndrome, inflammation, and organ damage. Empagliflozin was given in a daily dose of 10 mg/kg body weight for 8 weeks. Both age groups of SHR-CRP rats treated with empagliflozin had lower body weight, decreased weight of fat depots, reduced ectopic fat accumulation in the liver and kidneys, and decreased levels of plasma insulin and β-hydroxybutyrate. Empagliflozin effectively reduced ectopic renal fat accumulation, and was associated with decreased inflammation. Exclusively in young rats, decreased microalbuminuria after empagliflozin treatment was accompanied by attenuated oxidative stress. In adult animals, empagliflozin also improved left ventricle function. In conclusion, in young animals, the beneficial renoprotective effects of empagliflozin could be ascribed to reduced lipid deposition in the kidney and the attenuation of oxidative stress and inflammation. In contrast, hepatic lipid metabolism was ameliorated in adult rats. Full article

(This article belongs to the Special Issue Animal Models for Study of Pathophysiological Mechanisms of Hypertension and Its Complications)

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Open AccessArticle

How Effective Is a Late-Onset Antihypertensive Treatment? Studies with Captopril as Monotherapy and in Combination with Nifedipine in Old Spontaneously Hypertensive Rats

Christina Hawlitschek

and

Biomedicines 2022, 10(8), 1964; https://doi.org/10.3390/biomedicines10081964 - 12 Aug 2022

Cited by 1 | Viewed by 607

Abstract

Background: A major problem in the treatment of human hypertension is the late diagnosis of hypertension and, hence, the delayed start of treatment. Very often, hypertension has existed for a long time and cardiac damage has already developed. Therefore, we tested whether late-onset antihypertensive treatment is effective in lowering blood pressure (BP) and in reducing or even preventing left ventricular hypertrophy and fibrosis. Methods: Twenty-one male 60-week-old spontaneously hypertensive rats (SHR) were included. Fourteen rats received oral treatment with captopril (CAP) either as monotherapy or combined with nifedipine (CAP + NIF) over 22 weeks. Seven untreated SHR served as controls. We examined the therapeutic effects on BP, heart weight and histological and biochemical markers of left ventricular remodeling and fibrosis. Results: At 82 weeks of age, BP was reduced in the CAP and CAP + NIF groups by 44 and 51 mmHg, respectively (p < 0.001), but not in untreated controls. Despite the late therapy start, cardiac hypertrophy and fibrosis were attenuated compared to controls. Both treatments reduced heart weight by 1.2 mg/g (25%, p = 0.001) and collagens I and III by 66% and 60%, respectively (p < 0.001), thus proving nearly equivalent cardioprotective efficacy. Conclusion: These data clearly emphasize the benefit of antihypertensive treatment in reducing BP and mitigating the development of cardiac damage even when treatment is started late in life. Full article

(This article belongs to the Special Issue Animal Models for Study of Pathophysiological Mechanisms of Hypertension and Its Complications)

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Open AccessArticle

Elevated Vascular Sympathetic Neurotransmission and Remodelling Is a Common Feature in a Rat Model of Foetal Programming of Hypertension and SHR

Maria Sofia Vieira-Rocha

Joana Beatriz Sousa

Pilar Rodríguez-Rodríguez

Silvia Madaglena Arribas

and

Carmen Diniz

Biomedicines 2022, 10(8), 1902; https://doi.org/10.3390/biomedicines10081902 - 05 Aug 2022

Cited by 1 | Viewed by 773

Abstract

Hypertension is of unknown aetiology, with sympathetic nervous system hyperactivation being one of the possible contributors. Hypertension may have a developmental origin, owing to the exposure to adverse factors during the intrauterine period. Our hypothesis is that sympathetic hyperinnervation may be implicated in hypertension of developmental origins, being this is a common feature with essential hypertension. Two-animal models were used: spontaneously hypertensive rats (SHR-model of essential hypertension) and offspring from dams exposed to undernutrition (MUN-model of developmental hypertension), with their respective controls. In adult males, we assessed systolic blood pressure (SBP), diastolic blood pressure (DBP), heart rate (HR), sympathetic nerve function (³H-tritium release), sympathetic innervation (immunohistochemistry) and vascular remodelling (histology). MUN showed higher SBP/DBP, but not HR, while SHR exhibited higher SBP/DBP/HR. Regarding the mesenteric arteries, MUN and SHR showed reduced lumen, increased media and adventitial thickness and increased wall/lumen and connective tissue compared to respective controls. Regarding sympathetic nerve activation, MUN and SHR showed higher tritium release compared to controls. Total tritium tissue/tyrosine hydroxylase detection was higher in SHR and MUN adventitia arteries compared to respective controls. In conclusion, sympathetic hyperinnervation may be one of the contributors to vascular remodelling and hypertension in rats exposed to undernutrition during intrauterine life, which is a common feature with spontaneous hypertension. Full article

(This article belongs to the Special Issue Animal Models for Study of Pathophysiological Mechanisms of Hypertension and Its Complications)

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Open AccessArticle

Sacubitril/Valsartan and Ivabradine Attenuate Left Ventricular Remodelling and Dysfunction in Spontaneously Hypertensive Rats: Different Interactions with the Renin–Angiotensin–Aldosterone System

Kristina Krajcirovicova

and

Biomedicines 2022, 10(8), 1844; https://doi.org/10.3390/biomedicines10081844 - 31 Jul 2022

Cited by 1 | Viewed by 1059

Abstract

This study investigated whether sacubitril/valsartan and ivabradine are able to prevent left ventricular (LV) fibrotic remodelling and dysfunction in a rat experimental model of spontaneous hypertension (spontaneously hypertensive rats, SHRs) and whether this potential protection is associated with RAAS alterations. Five groups of three-month-old male Wistar rats and SHRs were treated for six weeks as follows: untreated Wistar controls, Wistar plus sacubitril/valsartan, SHR, SHR plus sacubitril/valsartan, and SHR plus ivabradine. The SHRs developed a systolic blood pressure (SBP) increase, LV hypertrophy and fibrosis, and LV systolic and diastolic dysfunction. However, no changes in serum RAAS were observed in SHRs compared with the controls. Elevated SBP in SHRs was decreased by sacubitril/valsartan but not by ivabradine, and only sacubitril/valsartan attenuated LV hypertrophy. Both sacubitril/valsartan and ivabradine reduced LV collagen content and attenuated LV systolic and diastolic dysfunction. Sacubitril/valsartan increased the serum levels of angiotensin (Ang) II, Ang III, Ang IV, Ang 1-5, Ang 1-7, and aldosterone, while ivabradine did not affect the RAAS. We conclude that the SHR is a normal-to-low serum RAAS model of experimental hypertension. While the protection of the hypertensive heart in SHRs by sacubitril/valsartan may be related to an Ang II blockade and the protective Ang 1-7, the benefits of ivabradine were not associated with RAAS modulation. Full article

(This article belongs to the Special Issue Animal Models for Study of Pathophysiological Mechanisms of Hypertension and Its Complications)

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Open AccessArticle

Cardiac Cx43 Signaling Is Enhanced and TGF-β1/SMAD2/3 Suppressed in Response to Cold Acclimation and Modulated by Thyroid Status in Hairless SHR^M

Katarina Andelova

Barbara Szeiffova Bacova

and

Biomedicines 2022, 10(7), 1707; https://doi.org/10.3390/biomedicines10071707 - 14 Jul 2022

Cited by 4 | Viewed by 953

Abstract

The hearts of spontaneously hypertensive rats (SHR) are prone to malignant arrhythmias, mainly due to disorders of electrical coupling protein Cx43 and the extracellular matrix. Cold acclimation may induce cardio-protection, but the underlying mechanisms remain to be elucidated. We aimed to explore whether the adaptation of 9-month-old hairless SHR^M to cold impacts the fundamental cardiac pro-arrhythmia factors, as well as the response to the thyroid status. There were no significant differences in the registered biometric, redox and blood lipids parameters between hairless (SHR^M) and wild type SHR. Prominent findings revealed that myocardial Cx43 and its variant phosphorylated at serine 368 were increased, while an abnormal cardiomyocyte Cx43 distribution was attenuated in hairless SHR^M vs. wild type SHR males and females. Moreover, the level of β-catenin, ensuring mechanoelectrical coupling, was increased as well, while extracellular matrix collagen-1 and hydroxyproline were lower and the TGF-β1 and SMAD2/3 pathway was suppressed in hairless SHR^M males compared to the wild type strain. Of interest, the extracellular matrix remodeling was less pronounced in females of both hypertensive strains. There were no apparent differences in response to the hypothyroid or hyperthyroid status between SHR strains concerning the examined markers. Our findings imply that hairless SHR^M benefit from cold acclimation due to the attenuation of the hypertension-induced adverse downregulation of Cx43 and upregulation of extracellular matrix proteins. Full article

(This article belongs to the Special Issue Animal Models for Study of Pathophysiological Mechanisms of Hypertension and Its Complications)

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Open AccessArticle

Activation of RAAS Signaling Contributes to Hypertension in Aged Hyp Mice

and

Biomedicines 2022, 10(7), 1691; https://doi.org/10.3390/biomedicines10071691 - 13 Jul 2022

Cited by 2 | Viewed by 969

Abstract

High circulating levels of fibroblast growth factor-23 (FGF23) are associated with left ventricular hypertrophy as well as increased morbidity and mortality in patients suffering from chronic kidney disease. However, the mechanisms underlying this association are controversial. Here, we aimed to further characterize the cardiovascular sequelae of long term endogenous FGF23 hypersecretion using 14-month-old male Hyp mice as a model of FGF23 excess. Hyp mice were characterized by a ~10-fold increase in circulating intact FGF23, hypophosphatemia, increased serum aldosterone, but normal kidney function, relative to wildtype (WT) controls. Cardiovascular phenotyping did not reveal any evidence of left ventricular hypertrophy or functional impairment in 14-month-old Hyp mice. Fractional shortening, ejection fraction, molecular markers of hypertrophy (Anp, Bnp), and intracardiac markers of contractility and diastolic function were all unchanged in these animals. However, intraarterial catheterization revealed an increase in systolic, diastolic, and mean arterial pressure of ~12 mm Hg in aged Hyp mice relative to WT controls. Hypertension in Hyp mice was associated with increased peripheral vascular resistance. To test the hypothesis that a stimulation of the renin–angiotensin–aldosterone system (RAAS) contributes to hypertension in aged Hyp mice, we administered the angiotensin receptor blocker losartan (30 mg/kg twice daily) or the mineralocorticoid receptor antagonist canrenone (30 mg/kg once daily) to aged Hyp and WT mice over 5 days. Both drugs had minor effects on blood pressure in WT mice, but reduced blood pressure and peripheral vascular resistance in Hyp mice, suggesting that a stimulation of the RAAS contributes to hypertension in aged Hyp mice. Full article

(This article belongs to the Special Issue Animal Models for Study of Pathophysiological Mechanisms of Hypertension and Its Complications)

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Review

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Open AccessReview

Role of Translationally Controlled Tumor Protein (TCTP) in the Development of Hypertension and Related Diseases in Mouse Models

Jeehye Maeng

and

Kyunglim Lee

Biomedicines 2022, 10(11), 2722; https://doi.org/10.3390/biomedicines10112722 - 27 Oct 2022

Cited by 1 | Viewed by 599

Abstract

Translationally controlled tumor protein (TCTP) is a multifunctional protein that plays a wide variety of physiological and pathological roles, including as a cytoplasmic repressor of Na,K-ATPase, an enzyme pivotal in maintaining Na⁺ and K⁺ ion gradients across the plasma membrane, by binding to and inhibiting Na,K-ATPase. Studies with transgenic mice overexpressing TCTP (TCTP-TG) revealed the pathophysiological significance of TCTP in the development of systemic arterial hypertension. Overexpression of TCTP and inhibition of Na,K-ATPase result in the elevation of cytoplasmic Ca²⁺ levels, which increases the vascular contractility in the mice, leading to hypertension. Furthermore, studies using an animal model constructed by multiple mating of TCTP-TG with apolipoprotein E knockout mice (ApoE KO) indicated that TCTP-induced hypertension facilitates the severity of atherosclerotic lesions in vivo. This review attempts to discuss the mechanisms underlying TCTP-induced hypertension and related diseases gleaned from studies using genetically altered animal models and the potential of TCTP as a target in the therapy of hypertension-related pathological conditions. Full article

(This article belongs to the Special Issue Animal Models for Study of Pathophysiological Mechanisms of Hypertension and Its Complications)

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Open AccessReview

Chloride Ions, Vascular Function and Hypertension

Kenichi Goto

and

Takanari Kitazono

Biomedicines 2022, 10(9), 2316; https://doi.org/10.3390/biomedicines10092316 - 18 Sep 2022

Viewed by 1320

Abstract

Blood pressure is determined by cardiac output and systemic vascular resistance, and mediators that induce vasoconstriction will increase systemic vascular resistance and thus elevate blood pressure. While peripheral vascular resistance reflects a complex interaction of multiple factors, vascular ion channels and transporters play important roles in the regulation of vascular tone by modulating the membrane potential of vascular cells. In vascular smooth muscle cells, chloride ions (Cl⁻) are a type of anions accumulated by anion exchangers and the anion–proton cotransporter system, and efflux of Cl⁻ through Cl⁻ channels depolarizes the membrane and thereby triggers vasoconstriction. Among these Cl⁻ regulatory pathways, emerging evidence suggests that upregulation of the Ca²⁺-activated Cl⁻ channel TMEM16A in the vasculature contributes to the increased vascular contractility and elevated blood pressure in hypertension. A robust accumulation of intracellular Cl⁻ in vascular smooth muscle cells through the increased activity of Na⁺–K⁺–2Cl⁻ cotransporter 1 (NKCC1) during hypertension has also been reported. Thus, the enhanced activity of both TMEM16A and NKCC1 could act additively and sequentially to increase vascular contractility and hence blood pressure in hypertension. In this review, we discuss recent findings regarding the role of Cl⁻ in the regulation of vascular tone and arterial blood pressure and its association with hypertension, with a particular focus on TMEM16A and NKCC1. Full article

(This article belongs to the Special Issue Animal Models for Study of Pathophysiological Mechanisms of Hypertension and Its Complications)

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Open AccessReview

Genetic Modifications to Alter Blood Pressure Level

Hiroki Ohara

and

Toru Nabika

Biomedicines 2022, 10(8), 1855; https://doi.org/10.3390/biomedicines10081855 - 01 Aug 2022

Viewed by 1133

Abstract

Genetic manipulation is one of the indispensable techniques to examine gene functions both in vitro and in vivo. In particular, cardiovascular phenotypes such as blood pressure cannot be evaluated in vitro system, necessitating the creation of transgenic or gene-targeted knock-out and knock-in experimental animals to understand the pathophysiological roles of specific genes on the disease conditions. Although genome-wide association studies (GWAS) in various human populations have identified multiple genetic variations associated with increased risk for hypertension and/or its complications, the causal links remain unresolved. Genome-editing technologies can be applied to many different types of cells and organisms for creation of knock-out/knock-in models. In the post-GWAS era, it may be more worthwhile to validate pathophysiological implications of the risk variants and/or candidate genes by creating genome-edited organisms. Full article

(This article belongs to the Special Issue Animal Models for Study of Pathophysiological Mechanisms of Hypertension and Its Complications)

Open AccessReview

Hypertension of Developmental Origins: Consideration of Gut Microbiome in Animal Models

You-Lin Tain

and

Chien-Ning Hsu

Biomedicines 2022, 10(4), 875; https://doi.org/10.3390/biomedicines10040875 - 09 Apr 2022

Cited by 5 | Viewed by 1576

Abstract

Hypertension is the leading cause of global disease burden. Hypertension can arise from early life. Animal models are valuable for giving cogent evidence of a causal relationship between various environmental insults in early life and the hypertension of developmental origins in later life. These insults consist of maternal malnutrition, maternal medical conditions, medication use, and exposure to environmental chemicals/toxins. There is a burgeoning body of evidence on maternal insults can shift gut microbiota, resulting in adverse offspring outcomes later in life. Emerging evidence suggests that gut microbiota dysbiosis is involved in hypertension of developmental origins, while gut microbiota-targeted therapy, if applied early, is able to help prevent hypertension in later life. This review discusses the innovative use of animal models in addressing the mechanisms behind hypertension of developmental origins. We will also highlight the application of animal models to elucidate how the gut microbiota connects with other core mechanisms, and the potential of gut microbiota-targeted therapy as a novel preventive strategy to prevent hypertension of developmental origins. These animal models have certainly enhanced our understanding of hypertension of developmental origins, closing the knowledge gap between animal models and future clinical translation. Full article

(This article belongs to the Special Issue Animal Models for Study of Pathophysiological Mechanisms of Hypertension and Its Complications)

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