Experimental Models Of Hypertension Research Articles

9246 Mineralocorticoid Receptor Regulation of the Molecular Clock in Cardiomyocytes Is Modulated by Time of Day

Abstract Disclosure: M. Kanki: None. S. Heanue: None. P.J. Fuller: None. T.J. Cole: None. C.D. Clyne: None. M.J. Young: None. The onset of cardiovascular disease events peaks in the early morning, which coincides with the diurnal surge in aldosterone and cortisol. Aldosterone-induced mineralocorticoid receptor (MR) activation in cardiomyocytes has established roles in cardiac pump function and electrophysiology and inappropriate MR activation promotes cardiovascular pathophysiology in experimental models of hypertension and heart failure and in the clinic. Recently, we identified a novel role for MR in regulating the circadian clock signalling network in cardiac cells and showed that time of day modulates MR activation in the heart. Whether time-of-day-dependent MR regulation of circadian clocks in cardiomyocytes modulates temporal expression of key functional pathways is unknown. Therefore, we sought to identify cardiac responsiveness to MR stimulation at lights on (7AM) versus lights off (7PM) in ≥8-week old male wildtype (WT) and cardiomyocyte-MR knockout (MyoMRKO) mice. RNA-seq analyses revealed that aldosterone (50 ug/kg) administered at 7PM but not at 7AM significantly enriched transcription of genes associated with 52 biological processes including “Circadian rhythm”, “Reg. of blood pressure”, “Ion transport” and “Reg. of the force of heart contraction” in WT hearts (p<0.05 versus 7PM vehicle-injected WT mice). These outcomes were absent in hearts isolated from MyoMRKO mice administered aldosterone at 7AM or 7PM. Analysis by RT-qPCR revealed that aldosterone versus vehicle administered at 7AM increased expression of circadian Period (Per) and Thyrotroph embryonic factor (Tef) genes in WT hearts, which was lost in MyoMRKO mice. Whole transcriptome analysis also detected significant enrichment in “Cell-cell signalling”, “Positive regulation of cell differentiation”, “Positive regulation of glucose metabolic process”, “Regulation of sodium ion transport”, and “Inflammatory response" processes between 7AM and 7PM in WT hearts, which was also lost in MyoMRKO mice. Our data show that MR transcription of genes associated with circadian rhythms and ion transport is temporally regulated, and demonstrates specificity for cardiomyocyte-MR regulation of circadian clocks. Taken together, we highlight that the role for cardiomyocyte-MR regulation of cardiac electrophysiology, heart rate variability, and metabolic processes is time-of-day-dependent. Understanding temporal coordination of MR activation in physiology and pathophysiology may inform new strategies for optimising MR-directed therapies in patients with heart disease. Presentation: 6/2/2024

7763 Mineralocorticoid Receptor Regulation of the Molecular Clock in Cardiomyocytes Is Modulated by Time of Day

Abstract Disclosure: M. Kanki: None. S. Heanue: None. P.J. Fuller: None. T.J. Cole: None. C.D. Clyne: None. M.J. Young: None. The onset of cardiovascular disease events peaks in the early morning, which coincides with the diurnal surge in aldosterone and cortisol. Aldosterone-induced mineralocorticoid receptor (MR) activation in cardiomyocytes has established roles in cardiac pump function and electrophysiology and inappropriate MR activation promotes cardiovascular pathophysiology in experimental models of hypertension and heart failure and in the clinic. Recently, we identified a novel role for MR in regulating the circadian clock signalling network in cardiac cells and showed that time of day modulates MR activation in the heart. Whether time-of-day-dependent MR regulation of circadian clocks in cardiomyocytes modulates temporal expression of key functional pathways is unknown. Therefore, we sought to identify cardiac responsiveness to MR stimulation at lights on (7AM) versus lights off (7PM) in ≥8-week old male wildtype (WT) and cardiomyocyte-MR knockout (MyoMRKO) mice. RNA-seq analyses revealed that aldosterone (50 ug/kg) administered at 7PM but not at 7AM significantly enriched transcription of genes associated with 52 biological processes including “Circadian rhythm”, “Reg. of blood pressure”, “Ion transport” and “Reg. of the force of heart contraction” in WT hearts (p<0.05 versus 7PM vehicle-injected WT mice). These outcomes were absent in hearts isolated from MyoMRKO mice administered aldosterone at 7AM or 7PM. Analysis by RT-qPCR revealed that aldosterone versus vehicle administered at 7AM increased expression of circadian Period (Per) and Thyrotroph embryonic factor (Tef) genes in WT hearts, which was lost in MyoMRKO mice. Whole transcriptome analysis also detected significant enrichment in “Cell-cell signalling”, “Positive regulation of cell differentiation”, “Positive regulation of glucose metabolic process”, “Regulation of sodium ion transport”, and “Inflammatory response" processes between 7AM and 7PM in WT hearts, which was also lost in MyoMRKO mice. Our data show that MR transcription of genes associated with circadian rhythms and ion transport is temporally regulated, and demonstrates specificity for cardiomyocyte-MR regulation of circadian clocks. Taken together, we highlight that the role for cardiomyocyte-MR regulation of cardiac electrophysiology, heart rate variability, and metabolic processes is time-of-day-dependent. Understanding temporal coordination of MR activation in physiology and pathophysiology may inform new strategies for optimising MR-directed therapies in patients with heart disease. Presentation: 6/2/2024

Antioxidative and cardioprotective effects of minocycline in ischemia/reperfusion injury in experimental model of hypertension.

Cardiovascular diseases remains leading cause of death and disabilities. Coronary artery occlusion and consequent ischemia leads to acute myocardial infarction, but restoration of blood flow, paradoxically, provokes further myocardial damage known as reperfusion injury. Minocycline is possessing anti-inflammatory and anti-apoptotic activity, immune-modulating and antioxidative properties besides its primary antibacterial effect. Recently it gained significant interest in preventing cardiac damage especially due to myocardial ischemia/reperfusion injury (MI/RI). The aim of this study was to assess the protective ability of pre-treatment and post-treatment of isolated hearts from healthy and spontaneously hypertensive rats with minocycline, on functional recovery and redox status after MI/RI using Langendorff technique. Using sensor in the left ventricle, the cardiodynamic parameters were recorded and in the samples of the coronary venous effluent oxidative stress biomarkers were analyzed. Minocycline was injected directly into the coronary vessels, in pre-treatment 5min before global ischemia, and in post-treatment during the first 5min of reperfusion. Changes in redox balance induced by minocycline were more prominent in post-treatment fashion of application. Cardioprotective effects of minocycline due to MI/RI are even more significant in hypertensive hearts. Minocycline showed significant cardioprotective effects, which was more pronounced in hypertensive compared to healthy hearts. Reduction of pro-oxidative biomarkers was more prominent in hypertensive hearts compared to the normotensive, especially if it is applied in the form of post-treatment. Minocycline could be important tool in reduction of heart damage induced by MI/RI due to its antioxidative potential, if these results are confirmed by clinical study.

Reactive oxygen species in hypertension.

Hypertension is a leading risk factor for stroke, heart disease and chronic kidney disease. Multiple interacting factors and organ systems increase blood pressure and cause target-organ damage. Among the many molecular elements involved in the development of hypertension are reactive oxygen species (ROS), which influence cellular processes in systems that contribute to blood pressure elevation (such as the cardiovascular, renal, immune and central nervous systems, or the renin-angiotensin-aldosterone system). Dysregulated ROS production (oxidative stress) is a hallmark of hypertension in humans and experimental models. Of the many ROS-generating enzymes, NADPH oxidases are the most important in the development of hypertension. At the cellular level, ROS influence signalling pathways that define cell fate and function. Oxidative stress promotes aberrant redox signalling and cell injury, causing endothelial dysfunction, vascular damage, cardiovascular remodelling, inflammation and renal injury, which are all important in both the causes and consequences of hypertension. ROS scavengers reduce blood pressure in almost all experimental models of hypertension; however, clinical trials of antioxidants have yielded mixed results. In this Review, we highlight the latest advances in the understanding of the role and the clinical implications of ROS in hypertension. We focus on cellular sources of ROS, molecular mechanisms of oxidative stress and alterations in redox signalling in organ systems, and their contributions to hypertension.

Imbalance of thalamic metabolites in an experimental model of hypertension: role of bergamot polyphenols

Abstract Funding Acknowledgements None. Hypertension is emerging as a pathogenic factor in vascular-based cognitive impairment, altering the structure and function of cerebral vasculature, and representing the main risk factor for cerebral small vessel diseases and neuronal loss. Some studies correlated a reduction in regional cerebral blood flow in the thalamus of elderly hypertensive brains with the decrease in certain cerebral metabolites, because of hypoperfusion. Patients with severe hypertension show a reduced oxygen consumption in regions with reduced cerebral blood flow suggesting that, the vascular dysfunction and the reduced cerebral blood flow could be related to reduced metabolic demands due to brain dysfunction and damage. Chronic cerebral hypoperfusion is associated with increased inflammatory state and oxidative stress. Herein, we hypothesized to prevent or reduce the onset of oxidative stress using natural occurring antioxidant compounds could be of particular importance for the management of hypertension-induced cerebral complications. Hypertension was induced on Wistar male rats by left renal artery ligation (RAL). After complete recovery from surgery, the animals were treated with 20 mg/kg deoxycorticosterone acetate twice a week for 4 weeks, and 1% sodium chloride (NaCl) water. A subgroup of hypertensive rats received Bergamot Polyphenolic Fraction (BPF) by gavage. A control group was treated with sub-cutaneous injection of saline. At baseline (T0), after 2 weeks (T1) and at the end of the experimental period (T2), the thalamic neurochemical profile were evaluated using proton magnetic resonance spectroscopy (1H-MRS), performed with a Bruker Pharmascan 70/16 7T. VAPOR water-suppression module was used and optimized to reduce residual water, then thalamic spectra were acquired using a short echo time single voxel point-resolved spectroscopy technique (voxel size 3x3x3 mm). The absolute quantification of metabolite concentrations has been performed using TARQUIN (v.4.3.10). A reduction tending to significance of the tNAA/tCr ratio, emerged in the thalamus of RAL DOCA-Salt rats compared to control rats at T2. A significant reduction of the tNAA/tCr ratio was observed in the group of RAL DOCA-Salt rats at the T2 compared to the same animals at the T1. In addition, a significantly decrease of the tCho/tCr ratio was highlighted in the RAL DOCA-Salt animals compared to the CTRL rats starting from the T1. The administration of BPF ameliorates the tNAA/tCr ratios in the thalamus of RAL DOCA-Salt rats. Such evidence of the influence of hypertension on tNAA/tCr and tCho/tCr ratios could better explain the relationship between brain structure and modulation of some metabolites, providing new insights into hypertension-induced brain complications and the contribution that the use of natural compounds could give to their management.

The protective effect of bergamot polyphenolic fraction on reno-cardiac damage induced by DOCA-salt and unilateral renal artery ligation in rats

Abstract Funding Acknowledgements None. The complex pathological interactions between renal and cardiovascular systems represent a real global epidemic and renovascular hypertension remains among the most prevalent, but also potentially reversible, risk factor for numerous reno-cardiac diseases in humans and pets. Here, we investigated the anti-inflammatory and reno-cardiac protective effects of a polyphenol-rich fraction of citrus bergamot (BPF) in an experimental model of hypertension induced by unilateral renal artery ligation (RAL). Adult male Wistar rats underwent unilateral renal artery ligation and treatment with 20 mg/kg deoxycorticosterone acetate (DOCA), twice a week for a period of 4 weeks, and 1% sodium chloride water. A subgroup of hypertensive rats received 100 mg/kg/day of BPF for 28 days, by gavage. Another group of animals was treated with a sub-cutaneous injection of vehicle (CTRL). RAL DOCA-Salt rats showed a significant increase in mean arterial blood pressure (MAP; p<0.05 vs CTRL) which strongly increased the resistive index (RI; p<0.05 vs CTRL) of contralateral renal artery flow and kidney volume after 4 weeks (p<0.001 vs CTRL). Renal dysfunction also led to a dysfunction of cardiac tissue strain associated with overt dyssynchrony in cardiac wall motion, as shown by the increased time-to-peak (T2P; p<0.05) and the decreased whole peak capacity (Pk; p<0.01) in displacement and strain rate (p<0.05) in longitudinal motion. The hearts of RAL DOCA-Salt rats showed a larger time delay between the fastest and the lowest region (Maximum Opposite Wall Delay-MOWD) (p<0.05 in displacement and p<0.01 in strain rate vs CTRL). A significant increase in the levels of the circulating pro-inflammatory cytokines and chemokines (p<0.05 for IL-12(40), p<0.01 for GM-CSF, KC, IL-13, and TNF- α) and in the NGAL expression of the ligated kidney (p<0.001) was observed.This pathological condition was prevented by BPF treatment, by reducing the increase of blood pressure in RAL DOCA-Salt rats (p<0.05) and exerting a protective effect on the volume of the contralateral kidney (p<0.01). BPF ameliorates cardiac tissue strain dysfunction by increasing Pk in displacement (p<0.01) and reducing the T2P in strain rate motion (p<0.05). These effects significantly improve MOWD (p<0.05) preventing the overt dyssynchrony in cardiac wall motion. The reno-cardiac protective effect of BPF was associated with a significant reduction in serum level of the pro-inflammatory cytokines and chemokines (p<0.05 for KC and IL-12(40), p<0.01 for GM-CSF, IL-13, and TNF- α)restoring physiological levels of NGAL (p<0.05) protein of the tethered kidney. In conclusion, the present results show that BPF promotes an efficient renovascular protection preventing the progression of inflammation and reno-cardiac damage, suggesting the potential clinical and veterinary role of dietary supplementation with the polyphenol-rich fraction of citrus bergamot in counteracting hypertension-induced reno-cardiac syndrome.

Pulmonary Hypertension and Anastrozole (PHANTOM): A Randomized, Double-Blind, Placebo-Controlled Trial.

Inhibition of aromatase with anastrozole reduces pulmonary hypertension in experimental models. We aimed to determine whether anastrozole improved six-minute walk distance (6MWD) at six months in pulmonary arterial hypertension (PAH). We performed a randomized, double-blind, placebo-controlled Phase II clinical trial of anastrozole in subjects with PAH at seven centers. Eighty-four post-menopausal women and men with PAH were randomized in a 1:1 ratio to receive anastrozole 1 mg or placebo by mouth daily, stratified by sex using permuted blocks of variable sizes. All subjects and study staff were masked. The primary outcome was the change from baseline in 6MWD at six months. Using intent-to-treat analysis, we estimated the treatment effect of anastrozole using linear regression models adjusted for sex and baseline 6MWD. Assuming 10% loss to follow-up, we anticipated having 80% power to detect a difference in the change in 6MWD of 22 meters. Forty-one subjects were randomized to placebo and 43 to anastrozole and all received the allocated treatment. Three subjects in the placebo group and two in the anastrozole group discontinued study drug. There was no significant difference in the change in 6MWD at six months (placebo-corrected treatment effect -7.9 m, 95%CI -32.7 - 16.9, p = 0.53). There was no difference in adverse events between the groups. Anastrozole did not show a significant effect on 6MWD compared to placebo in post-menopausal women and men with PAH. Anastrozole was safe and did not show adverse effects. Clinical trial registration available at www. gov, ID: NCT03229499.

Ultrasound Neuromodulation of an Anti-Inflammatory Pathway at the Spleen Improves Experimental Pulmonary Hypertension.

Inflammation is pathogenically implicated in pulmonary arterial hypertension; however, it has not been adequately targeted therapeutically. We investigated whether neuromodulation of an anti-inflammatory neuroimmune pathway involving the splenic nerve using noninvasive, focused ultrasound stimulation of the spleen (sFUS) can improve experimental pulmonary hypertension. Pulmonary hypertension was induced in rats either by Sugen 5416 (20 mg/kg SQ) injection, followed by 21 (or 35) days of hypoxia (sugen/hypoxia model), or by monocrotaline (60 mg/kg IP) injection (monocrotaline model). Animals were randomized to receive either 12-minute-long sessions of sFUS daily or sham stimulation for 14 days. Catheterizations, echocardiography, indices of autonomic function, lung and heart histology and immunohistochemistry, spleen flow cytometry, and lung single-cell RNA sequencing were performed after treatment to assess the effects of sFUS. Splenic denervation right before induction of pulmonary hypertension results in a more severe disease phenotype. In both sugen/hypoxia and monocrotaline models, sFUS treatment reduces right ventricular systolic pressure by 25% to 30% compared with sham treatment, without affecting systemic pressure, and improves right ventricular function and autonomic indices. sFUS reduces wall thickness, apoptosis, and proliferation in small pulmonary arterioles, suppresses CD3+ and CD68+ cell infiltration in lungs and right ventricular fibrosis and hypertrophy and lowers BNP (brain natriuretic peptide). Beneficial effects persist for weeks after sFUS discontinuation and are more robust with early and longer treatment. Splenic denervation abolishes sFUS therapeutic benefits. sFUS partially normalizes CD68+ and CD8+ T-cell counts in the spleen and downregulates several inflammatory genes and pathways in nonclassical and classical monocytes and macrophages in the lung. Differentially expressed genes in those cell types are significantly enriched for human pulmonary arterial hypertension-associated genes. sFUS causes dose-dependent, sustained improvement of hemodynamic, autonomic, laboratory, and pathological manifestations in 2 models of experimental pulmonary hypertension. Mechanistically, sFUS normalizes immune cell populations in the spleen and downregulates inflammatory genes and pathways in the lung, many of which are relevant in human disease.

A novel dual inhibitor of the angiotensin and endothelin systems for the treatment of hypertension

Hypertension, affecting nearly half of the US adult population, is a primary cause of morbidity and mortality worldwide. Despite the availability of several classes of antihypertensive medications, only 25% of patients have their blood pressure under control, highlighting the need for novel antihypertensive therapeutics with better effcacy. Among hypertensive cases, salt-sensitive and drug-resistant hypertension are particularly concerning, as they are unresponsive to a combined regimen of three or more classes of medications, including angiotensin II (Ang II) receptor blockers (ARBs), angiotensin-converting enzyme inhibitors (ACEis), and diuretics. Salt-sensitive, observed in 50% of the general and 73% of black hypertensive patients, disproportionately affects the latter, leading to significantly higher mortality. Salt-sensitive hypertension in humans, as well as in various experimental models of hypertension (e.g., Ang II-induced, Dahl-salt sensitive [DSS] rats, deoxycorticosterone acetate [DOCA]-salt hypertensive rats), is characterized by significantly elevated levels of plasma endothelin-1 (ET-1), oxidative stress, and kidney dysfunction. ET-1 is often considered a final common pathway in orchestrating cardiovascular dysfunction through a range of proinflammatory mediators such as Ang II, cytokines, hypoxia, thrombin, reactive oxygen species (ROS), oxidized LDL, and vasopressin, all of which stimulate ET-1 production. In this capacity, we report the discovery of a gut microbiota-derived metabolite, indole-3-acetic acid (IAA), that simultaneously blocks ET-1 receptors (ETAR and ETBR) and the ET-biosynthetic enzyme ECE-1. Our data demonstrate that IAA inhibits ET-1-induced constriction of resistance mesenteric arteries, ROS production in human aortic smooth muscle cells, activation of cultured endothelial cells, adhesion molecule expression, and leukocyte adhesion. IAA inhibited purified human ECE-1 and suppressed Ang-II-induced and hypoxia-elicited ET-1 production from endothelial cells in vitro. Administration of a once-daily, extended-release formulation of IAA inhibits blood pressure elevation and kidney dysfunction in both DSS and Ang II-induced hypertension. IAA treatment preserved endothelial nitric oxide (NO) production and maintained smooth muscle sensitivity to a NO donor, sodium nitroprusside. Furthermore, IAA inhibited the expression of ROS-associated proteins such as Nox2 and Nox4, reduced oxidative damages, and decreased the production of ET-1 in vivo. Overall, IAA is the first compound that, through novel dual targeting of both the angiotensin and endothelin systems, demonstrates profound antihypertensive action in both salt-sensitive and angiotensin II-induced hypertension. Thus, IAA has the potential to effectively treat hypertension that does not respond to conventional therapies. American Heart Association. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Clinical-experimental justification of the method of prevention and treatment of appendicular pylephlebitis

Taking into account the pathogenesis peculiarities of appendicular pylephlebitis, the risk group includes patients with a retrocecal location of the appendix, gangrenous and perforating appendicitis, the course of which was complicated by peritonitis or abscess. The purpose of our clinical-experimental study was to justify the method of pathogenetic treatment of acute appendicular pylephlebitis based on an experimental model of portal hypertension. Acute experiments were performed on male Wistar rats and outbred dogs. Clinical studies were prospectively-retrospective. In addition to traditional methods of treatment, we used the developed technique of draining the retroperitoneal space and introducing antibacterial compositions in a complex with a 10% dimethylsulfoxide (DMSO) solution was used. On the basis of experimental data, it was established that a 10% solution of DMSO complexed with a dye, when injected transperitoneally in the ileocecal angle area, preferentially penetrates the lymphatic and portal systems, even in conditions of portal hypertension. This is explained by the peculiarities of the anatomical structure. The use of the method of intraperitoneal administration of antibiotics in combination with DMSO is pathogenetically justified in patients with appendicular pylephlebitis, as it achieves local sanitation of the immediate source and primary ways of spreading the infection. Implementation of the developed method of prevention and treatment of acute pylephlebitis of appendicular genesis as part of improved treatment tactics allows to improve treatment results by likely reducing the frequency of postoperative complications from 18.7% to 2.7% (χ2 = 20.02, 95% CI 9.25-23.8) and the duration of hospitalization from 22.8 days to 8.5 days.

Gliflozins in the Treatment of Non-diabetic Experimental Cardiovascular Diseases.

A new class of antidiabetic drugs - gliflozins (inhibitors of sodium glucose cotransporter-2; SGLT-2i) stimulate glucose and sodium excretion, thereby contributing to improved glycemic control, weight loss and blood pressure reduction in diabetic patients. Large clinical trials in patients with type 2 diabetes treated with empagliflozin, canagliflozin or dapagliflozin have demonstrated their excellent efficacy in improving many cardiovascular outcomes, including the reduction of death from cardiovascular diseases, non-fatal myocardial infarction or stroke, and hospitalization for heart failure. Moreover, the beneficial effects of SGLT-2i were also demonstrated in the decrease in proteinuria, which leads to a lower risk of progression to end-stage renal disease and thus a delay in initiation of the renal replacement therapy. Unexpectedly, their cardioprotective and renoprotective effects have been demonstrated not only in patients with diabetes but also in those without diabetes. Recently, much effort has been focused on patients with heart failure (either with reduced or preserved ejection fraction) or liver disease. Experimental studies have highlighted pleiotropic effects of SGLT-2 inhibitors beyond their natriuretic and glycosuric effects, including reduction of fibrosis, inflammation, reactive oxygen species, and others. Our results in experimental non-diabetic models of hypertension, chronic kidney disease and heart failure are partially consistent with these findings. This raises the question of whether the same mechanisms are at work in diabetic and non-diabetic conditions, and which mechanisms are responsible for the beneficial effects of gliflozins under non-diabetic conditions. Are these effects cardio-renal, metabolic, or others? This review will focus on the effects of gliflozins under different pathophysiological conditions, namely in hypertension, chronic kidney disease, and heart failure, which have been evaluated in non-diabetic rat models of these diseases. Key words: SGLT-2 inhibitor, hypertension, chronic kidney disease, heart failure, liver disease, rat.

Effect of Benidipine Alone and in Combination With Bosentan and Sildenafil in Amelioration of Pulmonary Arterial Hypertension in Experimental Model in Rats.

Pulmonary arterial hypertension (PAH) is a persistent condition affecting the pulmonary arteries' endothelium. Benidipine, a calcium channel blocker, possesses vasodilatory, anti-inflammatory activity, reduces oxidative stress, and inhibits the activity of Transforming growth factor-β (TGF-β) and α-smooth muscle actin (α-SMA). The present study was designed to investigate the effect of benidipine alone and in combination with bosentan and sildenafil on monocrotaline (MCT)-induced pulmonary hypertension in a rat model. PAH was induced by a single-dose administration of MCT in rats. Animals were randomized into different groups and treated with benidipine alone and in combination with bosentan or sildenafil. Various parameters such as hemodynamic parameters, Fulton's index and oxidative stress parameters were performed. Additionally, histopathology of lung and right ventricular of heart tissue, immunohistochemistry, expression of α-SMA, endothelial nitric oxide synthase (eNOS), TGF-β, and RT-PCR, and an in vitro study using human umbilical vein endothelial cells (HUVECs) was also carried out. Treatment of benidipine and its combination exhibited better prevention in the elevated right ventricular systolic pressure, right ventricular hypertrophy, rise in oxidative stress, and increase in expression of α-SMA and TGF-β receptor 1 compared with MCT control group rats. In HUVECs, the expression of α-SMA was increased, whereas that of eNOS decreased after TGF-β exposure and was substantially reversed after pretreatment with benidipine. We concluded that benidipine and its combination with bosentan and sildenafil exhibit beneficial effects in MCT-induced PAH through the eNOS/TGF-β/α-SMA signaling pathway.

Reduced exercise capacity occurs before intrinsic skeletal muscle dysfunction in experimental rat models of pulmonary hypertension.

Reduced exercise capacity in pulmonary hypertension (PH) significantly impacts quality of life. However, the cause of reduced exercise capacity in PH remains unclear. The objective of this study was to investigate whether intrinsic skeletal muscle changes are causative in reduced exercise capacity in PH using preclinical PH rat models with different PH severity. PH was induced in adult Sprague-Dawley (SD) or Fischer (CDF) rats with one dose of SU5416 (20 mg/kg) injection, followed by 3 weeks of hypoxia and additional 0-4 weeks of normoxia exposure. Control s rats were injected with vehicle and housed in normoxia. Echocardiography was performed to assess cardiac function. Exercise capacity was assessed by VO2 max. Skeletal muscle structural changes (atrophy, fiber type switching, and capillary density), mitochondrial function, isometric force, and fatigue profile were assessed. In SD rats, right ventricular systolic dysfunction is associated with reduced exercise capacity in PH rats at 7-weektimepoint in comparison to control rats, while no changes were observed in skeletal muscle structure, mitochondrial function, isometric force, or fatigue profile. CDF rats at 4-weektimepoint developed a more severe PH and, in addition to right ventricular dysfunction, the reduced exercise capacity in these rats is associated with skeletal muscle atrophy; however, mitochondrial function, isometric force, and fatigue profile in skeletal muscle remain unchanged. Our data suggest that cardiopulmonary impairments in PH are the primary cause of reduced exercise capacity, which occurs before intrinsic skeletal muscle dysfunction.

Genetic and Epigenetic Mechanisms Regulating Blood Pressure and Kidney Dysfunction.

The pioneering work of Dr Lewis K. Dahl established a relationship between kidney, salt, and high blood pressure (BP), which led to the major genetic-based experimental model of hypertension. BP, a heritable quantitative trait affected by numerous biological and environmental stimuli, is a major cause of morbidity and mortality worldwide and is considered to be a primary modifiable factor in renal, cardiovascular, and cerebrovascular diseases. Genome-wide association studies have identified monogenic and polygenic variants affecting BP in humans. Single nucleotide polymorphisms identified in genome-wide association studies have quantified the heritability of BP and the effect of genetics on hypertensive phenotype. Changes in the transcriptional program of genes may represent consequential determinants of BP, so understanding the mechanisms of the disease process has become a priority in the field. At the molecular level, the onset of hypertension is associated with reprogramming of gene expression influenced by epigenomics. This review highlights the specific genetic variants, mutations, and epigenetic factors associated with high BP and how these mechanisms affect the regulation of hypertension and kidney dysfunction.

Modulation of TNF-α, interleukin-6, and interleukin-10 by nebivolol-valsartan and nebivolol-lisinopril polytherapy in SHR rats.

Antihypertensive drug therapies have demonstrated their capacity to modulate the inflammatory processes associated with hypertension, leading to improvements in disease progression. Given the prevalent use of polytherapy in treating most hypertensive patients, comprehending the time-dependent effects of combination treatments on inflammation becomes imperative. In this study, spontaneously hypertensive rats (SHR) were divided into seven groups (n = 6): (i) SHR + vehicle, (ii) SHR + nebivolol, (iii) SHR + valsartan, (iv) SHR + lisinopril, (v) SHR + nebivolol-valsartan, (vi) SHR + nebivolol-lisinopril, and (vii) WKY + vehicle. Blood pressure was measured using the tail-cuff method. Temporal alterations in inflammatory cytokines TNF-α, IL-6, and IL-10 were assessed in serum through ELISA and mRNA expression in aortic tissue via qPCR after 1, 2, and 4 weeks of treatment with nebivolol, lisinopril, valsartan, and their respective combinations. Histological alterations in the aorta were assessed. The findings indicated that combined treatments reduced systolic and diastolic blood pressure in SHR. The nebivolol and lisinopril combination demonstrated a significant decrease in IL-6 serum and mRNA expression at both 1 week and 4 weeks into the treatment. Additionally, TNF-α mRNA expression also showed a reduction with this combination at the same time points. Particularly, nebivolol-valsartan significantly decreased TNF-α serum and mRNA expression after one and four weeks of treatment. Furthermore, an elevation in serum IL-10 levels was observed with both combination treatments starting from the second week onwards. This study provides compelling evidence that concurrent administration of nebivolol with lisinopril or valsartan exerts time-dependent effects, reducing proinflammatory cytokines TNF-α and IL-6 while modifying IL-10 levels in an experimental hypertensive model.

Atlas of cardiac endothelial cell enhancer elements linking the mineralocorticoid receptor to pathological gene expression.

Endothelial cells play crucial roles in physiology and are increasingly recognized as therapeutic targets in cardiovascular disease. Here, we analyzed the regulatory landscape of cardiac endothelial cells by assessing chromatin accessibility, histone modifications, and 3D chromatin organization and confirmed the functional relevance of enhancer-promoter interactions by CRISPRi-mediated enhancer silencing. We used this dataset to explore mechanisms of transcriptional regulation in cardiovascular disease and compared six different experimental models of heart failure, hypertension, or diabetes. Enhancers that regulate gene expression in diseased endothelial cells were enriched with binding sites for a distinct set of transcription factors, including the mineralocorticoid receptor (MR), a known drug target in heart failure and hypertension. For proof of concept, we applied endothelial cell-specific MR deletion in mice to confirm MR-dependent gene expression and predicted direct MR target genes. Overall, we have compiled here a comprehensive atlas of cardiac endothelial cell enhancer elements that provides insight into the role of transcription factors in cardiovascular disease.

Cardiac and perivascular myofibroblasts, matrifibrocytes, and immune fibrocytes in hypertension; commonalities and differences with other cardiovascular diseases.

Hypertension is a major cause of cardiovascular diseases such as myocardial infarction and stroke. Cardiovascular fibrosis occurs with hypertension and contributes to vascular resistance, aortic stiffness, and cardiac hypertrophy. However, the molecular mechanisms leading to fibroblast activation in hypertension remain largely unknown. There are two types of fibrosis: replacement fibrosis and reactive fibrosis. Replacement fibrosis occurs in response to the loss of viable tissue to form a scar. Reactive fibrosis occurs in response to an increase in mechanical and neurohormonal stress. Although both types of fibrosis are considered adaptive processes, they become maladaptive when the tissue loss is too large, or the stress persists. Myofibroblasts represent a subpopulation of activated fibroblasts that have gained contractile function to promote wound healing. Therefore, myofibroblasts are a critical cell type that promotes replacement fibrosis. Although myofibroblasts were recognized as the fibroblasts participating in reactive fibrosis, recent experimental evidence indicated there are distinct fibroblast populations in cardiovascular reactive fibrosis. Accordingly, we will discuss the updated definition of fibroblast subpopulations, the regulatory mechanisms, and their potential roles in cardiovascular pathophysiology utilizing new knowledge from various lineage tracing and single-cell RNA sequencing studies. Among the fibroblast subpopulations, we will highlight the novel roles of matrifibrocytes and immune fibrocytes in cardiovascular fibrosis including experimental models of hypertension, pressure overload, myocardial infarction, atherosclerosis, aortic aneurysm, and nephrosclerosis. Exploration into the molecular mechanisms involved in the differentiation and activation of those fibroblast subpopulations may lead to novel treatments for end-organ damage associated with hypertension and other cardiovascular diseases.

Early detection of optic nerve head changes using optical coherence tomography after using mesenchymal stromal cells as intravitreal therapy in rabbit models of ocular hypertension.

Stem cell therapy is considered a promising treatment for several neurodegenerative diseases. However, there are very few studies on the use of this therapy in glaucoma models. By detecting the changes produced by glaucoma early, cell therapy could help prevent the events that lead to blindness. In this study, early changes in the optic nerve head (ONH) as detected by optical coherence tomography (OCT) after the application of human Wharton's jelly-derived mesenchymal stromal cells (hWJ-MSCs) in an experimental model of ocular hypertension (OH) were evaluated. Fifteen New Zealand rabbits were randomly divided into the following three groups: G1: OH, G2: hWJ-MSCs, and G3: OH + hWJ-MSCs. An OH model was constructed, and the intraocular pressure (IOP) was measured regularly. At week 7, 105/100 μL hWJ-MSCs were intravitreally injected. Retinography and OCT were used to evaluate structural changes in ONH. IOP increased significantly in G1 and G3 from week 3 onward. Retinography revealed more significant optic nerve changes, that is, papillary asymmetry suggestive of optic nerve excavation, vascular alterations, and irregular hypopigmentation peripheral to the optic disk margin, in G1 compared with G3. OH locates the hWJ-MSCs solution in the vitreous in front of the optic nerve. OCT revealed retinal nerve fiber layer (RNFL) reduction in all groups, reduced optic cup volume in G2 and G3 between weeks 1 and 9, and significant ganglion cell layer thickness reduction in G1 and a slight increase in G3. Intravitreal hWJ-MSCs injection produced changes in optic cup volume, which were detected early on by OCT; however, RNFL could not be restored in this OH model.

Impact of exercise training associated with enalapril treatment on blood pressure variability and renal dysfunctions in an experimental model of arterial hypertension and postmenopause.

In this study, we aimed to investigate the effects of the concurrent exercise training (CET) associated with the enalapril maleate on blood pressure variability (BPV) and renal profile in an experimental model of arterial hypertension (AH) and postmenopause. Female ovariectomized spontaneously hypertensive rats (SHR) were distributed into 4 groups (n = 8/group): sedentary (SO), sedentary + enalapril (SOE), trained (TO) and trained + enalapril (TOE). Both enalapril (3mg/kg) and CET (3 days/week) were conducted during 8 weeks. Blood pressure (BP) was directly recorded for BPV analyses. Renal function, morphology, inflammation and oxidative stress were assessed. The SOE, TO e TOE groups presented decreased systolic BP compared with SO. Both trained groups (TO and TOE) presented lower BPV and increased baroreflex sensitivity (TO: 0.76 ± 0.20 and TOE: 1.02 ± 0.40 vs. SO: 0.40 ± 0.07 ms/mmHg) compared with SO group, with additional improvements in TOE group. Creatinine and IL-6 levels were reduced in SOE, TO and TOE compared with SO group, while IL-10 was increased only in TOE group (vs. SO). Enalapril combined with CET promote reduction in lipoperoxidation (TOE: 1.37 ± 0.26 vs. SO: 2.08 ± 0.48 and SOE: 1.84 ± 0.35 μmol/mg protein) and hydrogen peroxide (TOE: 1.89 ± 0.40 vs. SO: 3.70 ± 0.19 and SOE: 2.73 ± 0.70 μM), as well as increase in catalase activity (vs. sedentary groups). The tubulointerstitial injury was lower in interventions groups (SOE, TO and TOE vs. SO), with potentialized benefits in the trained groups. Enalapril combined with CET attenuated BPV and baroreflex dysfunctions, probably impacting on end-organ damage, as demonstrated by attenuation in the AH-induced renal inflammations, oxidative stress and morphofunctional impairments in postmenopausal rats.

An updated review of experimental rodent models of pulmonary hypertension and left heart disease.

Left heart disease (LHD) is the leading cause of pulmonary hypertension (PH). Its recent growth has not been matched by the design of therapeutic agents directly targeting the disease. Effective therapies approved for pulmonary arterial hypertension (PAH) have been shown to be inefficient in patients with PH-LHD. Hence, there is a need for an animal model that would closely mimic PH-LHD in preclinical experiments. The current study describes and compares a number of rodent models of left ventricular failure and their potential to induce PH. It also evaluates whether, and to what extent, common PH models could develop LV failure. Articles were identified in the Pubmed/Medline and Web of Science online electronic databases following the PRISMA Protocol between 1992 and 2022. Quality assessment was carried out using the SYRCLE risk-of-bias tool for animal studies. Publication bias across studies using Egger's regression test statistic, was performed together with sensitivity analysis. A wide spectrum of protocols-135 studies and 207 interventions, was examined, including systemic hypertensive models, pressure-overload-induced HF, model of ischemic heart failure, and metabolic approaches based on high fat diet or metabolic syndrome. The most pronounced alterations in PH-related parameters were demonstrated for the common PH models, but were also seen in animals with LV failure induced by ischemic conditions, pressure overload or metabolic conditions. Models based on aortic banding, transverse aortic constriction (TAC), or with myocardial infarction (MI) caused by coronary artery ligation, demonstrated more pronounced worsening in PH due to LV failure; however, they also demonstrated poor survival, especially the ischemic-HF model. Common PH models, excluding prolonged exposure to monocrotaline, do not promote LV hypertrophy. Prolonged exposure to a high-fat diet, or a two-hit model of an obese ZSF1 rat combined with SU5416-induced pulmonary endothelial impairment (a VEGF receptor antagonist) worsened PH and impaired diastolic dysfunction. Due to the limited number of protocols, further trials are needed to confirm the utility of such approaches for modeling PH in subjects with metabolic syndrome. This would provide a clearer insight into the complexity of LHD, PH and metabolic disorders in PH-LHD, and thus accelerate the development of new therapies in clinical trials.