bluuebunny/crossref_metadata_2025 huggingface dataset:
Nek1 regulation of VHL and cilia
Authors: Patil Mallikarjun , Pabla navajotsingh , Dong Zheng
Published: June 2021

Nek1 is a member of NIMA related kinases in mammals that has been known to regulate ciliogenesis. Loss of function mutation in Nek1 leads to polycystic kidney disease in mouse and renal cysts in humans. pVHL, a well known tumor suppressor, has been recently implicated in the regulation of cilia and cell cycle. Loss of VHL function leads to renal cystic disease and renal cell carcinoma. Since mutation of Nek1 and VHL results in similar phenotype, we investigated if Nek1 and pVHL might function in a common regulatory pathway. Our in vitro and in vivo experiments show that pVHL may be a substrate of Nek1. Phosphorylation of VHL by Nek1 may affect the stability of pVHL and cilia dynamics. Phosphorylation site mutations in pVHL results in higher stability. Cells expressing mutant pVHL have stable cilia, resistant to serum stimulation and Nocodazole treatment. Phosphorylation of VHL by Nek1 does not seem to affect hypoxia inducible factors (HIF). Together, the results reveal a novel regulation of pVHL by Nek1, which may contributes to the regulation of cilia.

This study was supported by NIH
miRNA‐141 is a potential regulator of the mitochondrial phosphate carrier (slc25a3) in the type 1 diabetic heart
Authors: Thapa Dharendra , Baseler Walter A , Jagannathan Rajaganapathi , Dabkowski Erinne R , Croston Tara L , Nichols Cody E , Shepherd Danielle L , Lewis Sara E , Hollander John M
Published: June 2021

Cardiomyopathy is a leading cause of mortality among patients with diabetes mellitus. Dysfunctional mitochondria are central in the pathogenesis of diabetic cardiomyopathy. Mitochondrial proteomic alterations during diabetes mellitus have been reported however, the mechanisms responsible are unknown. The goal of this study was to determine whether miRNAs, specifically miRNA‐141, play a role in diabetes‐induced proteomic dysregulation. miRNA screening in diabetic mice following multiple low‐dose streptozotocin treatment revealed a significant increase in the expression of 10 miRNAs in the heart, including miRNA‐141 (P<0.05). Target scan analyses identified miRNA‐141 as a potential regulator of the inner membrane phosphate transporter, solute carrier family 25 member 3 (slc25a3), which provides inorganic phosphate essential for ATP production. miRNA‐141 overexpression in HEK 293 cells elicited a decrease in slc25a3 protein content similar to the diabetic phenotype (P<0.05). Moreover, ATP synthase activity was decreased in miRNA‐141 overexpressed HEK 293 cells similar to diabetes mellitus. Together these results indicate that miRNA‐141 could be a potential regulator of slc25a3 protein expression in the diabetic heart. Further, diabetes‐induced miRNA changes may influence mitochondrial proteomes and functional processes.(Support: NIH DP2DK083095, NIH T32HL090610, AHA 10PRE3420006)
Effects of exercise training on adipokines and glucose tolerance in non‐obese spontaneously type 2 diabetic torii rats
Authors: Kondo Hiroyo , Fujino Hidemi , Murakami Shinichiro , Nagatomo Fumiko , Morifuji Takeshi , Fujita Naoto , Tanaka Masayuki , Ishihara Akihiko
Published: June 2021

The male Spontaneously Diabetic Torii (SDT) rats develop hyperglycemia spontaneously without obesity. The purpose of present study was to investigate the effect of exercise training in SDT rat. The male SDT rats (10 weeks old) were randomly divided into an exercise training group (SDT+Ex) and a sedentary group (SDT), while the Sprague Dawley (SD) rats were used as control groups (SD+Ex and SD). The SDT+Ex and SD+Ex rats were trained on a treadmill at speeds up to 15 m/min for 60 min, 5 times per week for 14 weeks. An oral glucose tolerance test with estimation of total area under the curve (AUC), HbA1c, insulin, adiponectin, leptin and adipose tissue mass were measured. The level of blood glucose in SDT+Ex was significantly lower than that in SDT at 16 – 24 weeks old. In additon, AUC, HbA1c and epididymal adipose tissue mass in SDT were significantly higher relative to SD although there was no difference among SDT+Ex, SD+Ex and SD. Furthermore, there was no significant difference between the all groups in insulin and leptin levels. Although the level of adiponectin was significantly lower in SDT and higher in SDT+Ex rat than in SD rat. These results indicate that exercise training attenuates hyperglycemia and the decrease of adiponectin in non‐obese type 2 diabetes. Supported by Grants‐in‐Aid for Science Research from the Japanese Ministry of Education, Culture, Sports, Science and Technology.
Monoamine oxidase and ATPase activity in intrapulmonary arteries in Broiler chickens with IPAH
Authors: Kluess Heidi A , Evanson Kirk W , Stone Audrey J , Wideman Robert F
Published: June 2021

Vasoconstrictors, like serotonin and ATP, are suspected in causing high pulmonary arterial vascular resistance in people and Broilers with IPAH. The purpose was to evaluate the activity of key enzymes that breakdown serotonin and ATP since the balance between release and metabolism controls the amount of vasoconstriction that occurs. A diet supplemented with excess tryptophan (High‐TRP diet), the precursor for serotonin, was used. Intrapulmonary arteries were dissected and homogenized. Luminometric and spectrophotometric assays were used to quantify monoamine oxidase and ATPase activity. There was no effect of diet on ATPase activity. However, the 2A arterioles had greater phosphatase activity (8.35 ± 9.34 μM phosphate/μg protein/min; n = 20) compared to the pulmonary rami (3.80 ± 2.43 μM phosphate/μg protein/min; p<0.05; n = 20). Monoamine oxidase activity in the Control group (3,559±1,169 relative luminescence units (RLU), n=3) was greater in magnitude than in the High‐TRP group (83±186 RLU, p<0.05, n=5) in the pulmonary rami. For the 2A arterioles, monoamine oxidase activities did not differ between the Control group and the High‐TRP group. ATPase activity was highest in the smallest arterioles, but was unaffected by the treatment. However, monoamine oxidase activity was nearly abolished by the dietary treatment, suggesting that the ability to metabolize serotonin may be impaired in animals with IPAH.
Enhancement of the large conductance, Ca2+‐activated K+ (BK) channel current by cGMP‐dependent protein kinase requires multiple phosphorylation sites on the C‐terminal tail
Authors: Kyle Barry D , Hurst Soleil , Braun Andrew P
Published: June 2021

Nitric oxide (NO)‐mediated activation of the cGMP‐dependent protein kinase (cGK) leads to relaxation of vascular smooth muscle (VSM) through a process involving phosphorylation of the BK channel. In VSM cells, this modification increases channel open probability, resulting in membrane hyperpolarization and closure of voltage‐gated Ca2+ channels. Although this paradigm is now generally accepted, the target residues of cGK‐mediated phosphorylation on the BK channel have thus far been inadequately characterized at the molecular level. We have scrutinized this BK channel phosphorylation by identifying several putative phosphorylation sites on the C‐terminus via electrophysiological and biochemical assays. Wild type (WT) and Ser to Ala mutated BK channels were expressed in cultured rat aortic VSM cells (A7r5) and studied using the cell‐attached patch clamp technique. The NO donor spermine NONOate (5 μM) and the membrane‐permeant analogue db‐cGMP (0.1 mM) enhanced WT BK channel activity, while several BK channel mutants had diminished responses to either stimulant. Exposure to the Ca2+ ionophore A23187 enhanced channel activity in both WT and mutant channels. These results demonstrate that BK current enhancement by NO/cGK‐mediated phosphorylation requires multiple sites on the C‐terminus tail, in an apparent all‐or‐none fashion. Supported by NSERC (APB) and a Kertland Family Scholarship (BDK).
Wall stress initiates the nuclear export and degradation of phosphorylated myocardin in vascular smooth muscle cells
Authors: Pfisterer Larissa , Feldner Anja , Hecker Markus , Korff Thomas
Published: June 2021

Myocardin controls the expression of genes stabilizing the contractile phenotype of vascular smooth muscle cells (SMC) by binding to the CArG box of serum response factor. Despite its crucial role in the development of the embryonic vasculature, its impact on the phenotype of adult SMCs still is poorly understood. We observed a significant decrease in myocardin abundance in SMCs of mouse arteries upon in vivo exposure to increased wall stress (e.g. hypertension), accompanied by downregulation of target genes such as calponin and an increase in proliferation. In SMCs of isolated mouse arteries myocardin level strongly decreased upon a supraphysiological increase in transmural pressure. Subsequent analyses of human cultured SMCs exposed to enhanced stretch, suggested that this biomechanical force elicits the nuclear export of phosphorylated myocardin. Followed by its proteasomal degradation in the cytoplasm.

These findings suggest that increased wall stress triggers the nuclear export of myocardin and its proteasomal degradation in arterial SMCs through an as yet unknown mechanism. This process may determine the switch towards the synthetic phenotype and thus control the onset of arterial remodeling.
Interplay between gap junctions and K2P‐channels: the switch from PDBu‐elicited contraction to the dilation of the thoracic aorta
Authors: Bychkov Rostislav , Cubano Luis , Hayoz Sebastien , Maldonado Hector
Published: June 2021

Phorbol‐12,13‐dibutyrate (PDBu) an activator of protein kinase C (PKC) was shown to mediate contraction in several vascular beds. PDBu (1μM) increased amplitude of the K+‐currents in freshly isolated myocytes from the aorta. The fraction of PDBu‐elicited K+‐currents was inhibited by “cocktail” of K+‐blockers: TEA (3mM), 4AP (3mM), charibdotoxin (200nM), apamin (1μM) and glibenclamide (10μM) (n=27). The amplitude of the “cocktail” blockers resistive whole cell K+‐currents were reduced partially by Zn (40μM), acid pH (6.5), Ba (300μM) and mercury Hg (5μM). Aorta rings mounted on Mulvany myograph were stretched by step pulse of 8 mN. “Cocktail” of K+‐blockers contracted pre‐stretched aorta. PDBu added cumulatively to the bath solution further contracted aorta. Carbenoxolone (200μM) added to the bath solution prior to the PDBu produced partial dilation of the aorta. PDBu added cumulatively to the carbenoxolone dilated all aorta rings. Go 6983 (20μM) nonselective PKC inhibitor antagonized PDBu‐elicited dilation. Low extracellular pH, zinc and mercury partially antagonized PDBu‐elicited dilation. Our data suggest that PKC contracts the aorta and opens K2P channels simultaneously. PKC dilated the aorta when intercellular coupling via gap junctions was inhibited. We propose that ratio between open gap junctions and K2P channels may switch from PKC mediated vasoconstriction to vasodilation.
IN VITRO TOLERANCE AFTER INCUBATION WITH NITROGLYCERIN (NTG) IS DUE TO INCREASED REACTIVE OXIGEN SPECIES IN THE ENDOTHELIAL CELLS
Authors: de Rezende Dias Vania Braghini , Silva Bruno Rodrigues , Pernomian Laena , Bendhack Lusiane Maria
Published: June 2021

NTG may cause tolerance during long‐term administration, which is its major therapeutic limitation. However, the mechanisms underlying NTG‐induced tolerance and the contribution of endothelial cells (EC) remain unclear. We have verified that the endothelium modulates the vasodilatation induced by NTG in rat aorta. This work aimed to study the effects of nitric oxide (NO) and reactive oxygen species (ROS) on NTG‐induced relaxation in rat aorta and in isolated EC in order to investigate the cause of the in vitro tolerance. Relaxation curves for NTG were constructed in intact endothelium (E+) aortic rings. It was determined the efficacy (ME) and potency (pD2) of NTG. L‐NAME reduced the pD2 (from 8.70±0.13 to pD2 7.83±0.15) and ME from 102.7±2.7%, n=10 to 69.8± 3.2%, n=5 (p<0.001). To study the tolerance in vitro, the E+ arteries were incubated for 5 min with NTG in the concentration that produced the ME: 100 μM. The ME and pD2 were reduced (from 101.9±1.6%; n=5 to 54.7±3.6%, n=5 p<0.001; and from 8.88±0.20 to 7.63±0.04; n=5, p<0.05), respectively. Following 5 min incubation, NTG enhanced the fluorescence intensity units (U) of superoxide (O2−) concentration by flow citometry (from basal 2.19±0.58U to 54.15±1.49U, p<0.001). NO concentration was not changed in the EC. In conclusion, the in vitro tolerance is induced by 5 min incubation with NTG with increased production of superoxide in aortic EC. Supported by FAPESP and CNPq.
Mechanism of hydrogen sulfide mediated contraction in rat small pulmonary arteries
Authors: Aaronson Philip Irving , Prieto-Lloret Jesus , Snetkov Vladimir , Connolly Michelle , Ward Jeremy
Published: June 2021

The gas H2S (sulfide) causes a biphasic contraction of unknown mechanism in pulmonary arteries (PA). We assessed this mechanism in rings of rat 2nd order PA using myography to measure tension and NaHS as a source of sulfide. Reactive oxygen species (ROS) levels and the mitochondrial membrane potential (Δψ) were recorded using the indicators LO12 and TMRE, respectively. NaHS (500μM) evoked a small contraction and then a much larger 2nd contraction which gradually relaxed. The 2nd contraction was strongly reduced by 10μg/ml antimycin (AM) and 50μM dantrolene but was unaffected by 1μM rotenone (ROT). 10 or 30μM sulfide caused an immediate transient rise in [ROS]; at 100–1000μM this was followed by a 2nd larger rise in ROS which fell to baseline within ~10 min. The biphasic increases in tension and ROS had similar timecourses. The rise in [ROS] was slightly blocked by 1μM ROT but was almost abolished by 10μg/ml AM. 500 μM sulphide caused a triphasic effect on Δψ: a rapid very transient hyperpolarization was followed by a depolarization, a 2nd slower hyperpolarization, and then a return to baseline. Sulfide oxidation by the mitochondrial flavoprotein sulfide‐quinone oxoreductase (SQR), which is expressed in PA, has been shown in some cells to generate electrons that are passed to complex 3. We propose that metabolism of sulfide by SQR gives rise to a complex 3‐mediated increase in ROS that causes a contraction by activating the RyR.
Atherogenic Index of Plasma: A significant indicator for the onset of Atherosclerosis During Menopause in Hypertensive Females of Southeast Nigeria
Authors: Igweh John Chukwuka
Published: June 2021

SUMMARY BACKGROUND

Hypertension and menopause are independent risk factors for dyslipidaemia. In normotensive subjects, menopause causes significant alteration in lipid levels that may require medical intervention. It is thus expected that this alteration will become more relevant in hypertensive menopausal subjects. In our environment, diverse dietary, socioeconomic, and geographical variables might alter the expected pattern of deraignment.

AIMS AND OBJECTIVES

This study aims to compare the total lipid profile and its subfractions in hypertensive premopausal and hypertensive postmenopausal subjects.

MATERIALS AND METHODS

This is a comparative, cross sectional cohort study involving 116 hypertensive females (67 premenopausal and 49 postmenopausal) consecutively recruited over a two year period. Serum total cholesterol and its sub fractions, high density lipoprotein (HDL), low density lipoprotein (LDL), Very low density lipoprotein (VLDL), and triglyceride, (TG) were estimated using standardized enzymatic and mathematical methods. Significant differences were analysed with student T –test using SPSS version 11 computer software.

RESULTS

There were no statistically significant differences in total cholesterol, HDL, LDL, VLDL and HDL/LDL ratio between the two groups (P> 0.05). However there were statistically significant differences in triglycerides and the atherogenic index of plasma (P<0.05).

CONCLUSION

Simultaneous occurrence of menopause and hypertension leads to alteration in lipid profile that favours the use of triglyceride based indices (instead of HDL/LDL ratio) in determining the risk of developing atherosclerosis.
Progression of microalbuminuria in SHR is associated with diminished expression of proteins that belong to the receptor‐mediated endocytosis macromolecular complex
Authors: Inoue Bruna Hitomi , Machado Marcos Oporini , Girardi Adriana C
Published: June 2021

Microalbuminuria is recognized to be a risk factor for cardiovascular and kidney disease and is associated with morbidity and mortality in hypertensive patients. It arises as a consequence of increased glomerular permeability and/or reduced tubular reabsorption. The aims of the present study were: (1) to analyze the temporal evolution and the pattern of urinary protein excretion in spontaneously hypertensive rats (SHR), and (2) to evaluate whether the expression of proteins implicated in receptor‐mediated endocytosis in the renal proximal tubule of SHR can vary with blood pressure. Urinary protein excretion was evaluated in 6, 14 and 21 week‐old SHR and in Wistar rats of corresponding age. Daily urinary protein excretion increased with the development of hypertension in SHR (15 ± 1; 71 ± 2 and 112 ± 6 mg/day at 6, 14 and 21 weeks respectively), but remained unchanged in normotensive rats. SDS‐PAGE analysis of urinary proteins showed that SHR displayed a progressive increase of intact urinary albumin excretion with age. Progression of microalbuminuria highly correlated with elevation of arterial blood pressure in SHR (0.91; P<0.0001). Moreover, during the period of 6 to 21 weeks of age, SHR only excreted proteins of the size of albumin or smaller. The expression of the endocytic receptors megalin and cubilin, the B2‐subunit of the H+‐ATPase and the ClC‐5 chloride channel decreased as blood pressure increased in SHR but remained unaltered in Wistar rats. Furthermore, western blot analysis of urine samples revealed that the urinary excretion of transferrin, a protein known to be reabsorbed via receptor mediated endocytosis, increases as blood pressure increases in SHR. Taken together these data suggest that SHR displays tubular proteinuria after development of hypertension at least in part due to a decrease of some components of the receptor‐mediated endocytosis macromolecular complex.

Support: FAPESP
ER stress inhibition reduces cardiac damage and improves endothelial function in hypertensive mice
Authors: Kassan Modar Omar , Galan Maria , Partyka Megan , Henrion Daniel , Trebak Mohamed , Matrougui Khalid
Published: June 2021

Vascular complications and cardiac damage are major cause of mortality in hypertension. In this study we explored the beneficial effect of ER stress inhibition on vascular and cardiac damage in hypertension

Mice were infused with Ang‐II with or without ER stress inhibitors (Tudca and PBA) for 2 weeks Mice infused with Ang‐II displayed an increase in SBP, cardiac hypertrophy and fibrosis associated with enhanced collagenI content, TGFb activity and ER stress markers which were blunted by ER stress inhibitors. AngII induced hypertension increased ER stress in aorta and mesenteric resistance arteries (MRA) enhanced TGFb activity in aorta but not in RA, reduced eNOS phosphorylation and endothelium‐dependent relaxation (EDR) in aorta and MRA. ER stress inhibition reduced TGFb fnactivity, enhanced eNOS phosphorylation and EDR. TGFb pathway inhibition improved EDR in aorta while the reduction in ROS levels ameliorated EDR in MRA only

ER stress inhibition reduces cardiac damage and improves vascular function in Ang II‐induced hypertension. ER stress could be a potential target for cardiovascular therapy
The correlation of pharmacodynamic activity of mineralocorticoid receptor antagonism with its blood pressure lowering effect in rat with the remnant kidney
Authors: Ma Xiuying , Contino Lisa , Stribling Sloan , Chen Nancy , Yi Pan , Wang Li , Price Olga , Loewrigkeit Christopher , Keohane Carol Ann , Jochnowitz Nina , Parlapiano Allison , Gichuru Loise , Ping Xiaoli , Wickham Alexandra , Szeto Daphne , Crook Martin , Pai Lee-Yuh , Metzger Joseph
Published: June 2021

Blockade of aldosterone action on the kidney with mineralocorticoid receptor antagonist spironolactone (SPL) or eplerenone (EPL) leads to increased natriuresis and decreased kaliuresis and has proven clinically effective for the treatment of hypertension and heart failure. However, a direct correlation between blood pressure (BP) lowering and the increased natriuretic effect in response to chronic administration of MR antagonist has not been well characterized. In the present study, our goal was to understand whether MR antagonist induces increased natriuresis overtime and therefore correlates to BP lowering in a hypertensive rat model with renal mass reduction (remnant kidney). Animals with the remnant kidney developed sustained systemic hypertension (140–180 mmHg), and their BP and urine chemistry was continuously monitored before and during the drug treatment with vehicle or SPL (30–100mg/kg) administered orally for 4 weeks. Following the 4 week chronic administration of SPL, systolic BP was dose‐dependently reduced by up to 15 mmHg, which was also accompanied with a marked attenuation in proteinuria. However, SPL induced initial increases in natriuresis and decreases in kaliuresis were gradually diminished over the course of the study. These findings clearly demonstrate that the BP lowering effect of SPL is not correlated with its chronic natriuretic effect in the hypertensive rat with remnant kidney.
Central nNOS neuron functions to compensate salt‐sensitive hypertension in Dahl rats.
Authors: Nishida Yasuhiro , Tandai-Hiruma Megumi , Kemuriyama Takehito , Maruyama Satoshi , Ohta Hiroyuki , Tashiro Akimasa , Takashi Iwakawa , Tamura Risa , Hagisawa Kohsuke
Published: June 2021

Salt‐sensitive hypertension produces central nNOS neurons enhanced markedly in the number of neurons and enzymatic activity. Which of salt‐load, high blood pressure or rat line causes enchancement has not been clarified. To determine the cause of the enhancement, high blood pressure was suppressed by nifedipie in Dahl salt‐sensitive (DSS) hypertensive rats fed 8% salt food, resulting in no enhacement was found in central nNOS neurons. The result indicates that high blood pressure per se may induce central nNOS enhancement. Central nNOS neurons are known to suppress blood pressure‐controlling sympathetic activity in acute phase. Then next, to determine if its sympathoinhibitory effect works in long‐term, a selective inhibitor, S‐methiy‐L‐thiocitrulline (SMTC), was intracerebroventricularly (icv) infused for 2 weeks, and arterial pressure was measured by a radiotelemetry method in DSS hypertensive rats fed 8% NaCl food, resulting in that chronic icv SMTC enhanced more hypertension. These results suggested that central nNOS neurons may function to suppress sympathetic activity to compensate high arterial pressure for lowering in salt‐sensitive hypertension.
Impaired Endothelial Function in Ovariectomised Rats: Effects of Tempol
Authors: Wang Dan , Ji Hong , Zheng Wei , Wu Xie , Welch William J , Sandberg Kathryn , Wilcox Christopher S
Published: June 2021

Menopause causes endothelial dysfunction. We investigated the hypothesis that reactive oxygen species (ROS) mediate the adverse effects of ovariectomy (OVX) on microvessels. Mesenteric arterioles (MAs) were isolated from rats 4–6 weeks after sham‐operation (S) or OVX alone, S or OVX rats were given vehicle or tempol (2 mmol · l−1) throughout (n=6/group) to measure endothelium derived relaxation factor (EDRF) and endothelium dependent contracting factor (EDCF) using a wire myograph. NO and ROS were quantitated by DAF‐FM and tempo‐9AC‐fluorescence using RatioMasterTM. OVX rats had increased mean blood pressure (MBP) (114±7 vs 88±6.5 mmHg, P<0.05). Their MAs had increased medium:lumen ratio (4.44±0.38 vs 1.54±0.29, P<0.01) and EDRF (20±4 vs 41±4%, P<0.001) and decreased NO activity (0.37±0.1 vs 0.7±0.1 Units, P<0.01). However, OVX rats developed a new EDCF response (20±6 vs 5±5%, P<0.05) accompanied by increased ROS activity (0.22±0.09 vs 0.10±0.01 units; P<0.01). Tempol prevented significant changes in BP, vascular remodeling, EDRF and NO activity, and prevented any EDCF or ROS responses in OVX rats. In conclusion, OVX causes hypertension and microvascular remodeling and redirects endothelial responses from relaxation to contraction accompanied by reduced vascular NO and enhanced ROS. All of these effects are dependent on ROS and could, therefore, be targeted with effective antioxidant therapy.
Exercise training modulates right ventricular function and remodeling in experimental pulmonary arterial hypertension
Authors: Gonçalves Daniel , Fonseca Hélder , Ferreira Rita , Padrão Ana Isabel , Vasques-Nóvoa Francisco , Vieira Sara , Pinto Manuel , Gonçalves Nadia , Neto Marina , Paixão Rodney , Amado Francisco , Duarte José Alberto , Leite-Moreira Adelino , Henriques-Coelho Tiago
Published: June 2021

Right ventricle failure (RVF) is a major determinant of survival in pulmonary arterial hypertension (PAH). Exercise training was shown to be beneficial in left ventricle failure but its impact on RVF remains unknown. We investigated whether exercise training modulates the right ventricular response to chronic pressure overload in monocrotaline (MCT) model of PAH. Male Wistar rats were submitted to normal cage activity (SED+MCT) or to treadmill exercise training (EXtreat+MCT) after the establishment of RV pressure overload induced by MCT (60 mg/kg). Exercise training attenuated cardiac hypertrophy, improved cardiac function and survival. Exercise training normalized RV SERCA2a protein levels, beta/alpha MHC isoform, ET‐1 and VEGF mRNA, cardiac fibrosis and inflammation. Mitochondrial function was preserved and was accompanied by reduced oxidative damage. These data suggest that exercise training is cardioprotective in RVF induced by experimental PAH and provide some insights about the putative underlying cardioprotective mechanisms.
An Experimental Chronic Obstructive Pulmonary Disease Model Induced by Cigarette Smoke and Bacterial Infection
Authors: LI Ya , LI Jiansheng , LI Suyun , DENG Li , TIAN Yange , JIANG Suli , WANG Ying , WANG Yuanyuan
Published: June 2021

To develop a stable chronic obstructive pulmonary disease (COPD) model, rats were treated with cigarette‐smoke inhalation (CSI), repetitive bacterial infection (RBI) or the combination of CSI and RBI (CCR), respectively. After 8 week treatment, tidal volume (VT), peak expiratory flow (PEF), 50% tidal volume expiratory flow (EF50) and right ventricular hypertrophy index (RVHI) decreased in CSI or RBI‐treated rats compared to the control rats. CSI and RBI treatment also caused the increases in cytokine levels including tumor necrosis factor (TNF)‐α, interleukin (IL)‐8 and 10 in blood serum and bronchoalveolar lavage fluid (BALF). H&E staining showed that bronchiole and arteriola wall thickness, degree of bronchiole stenosis and alveolar size increased in rats treated with CSI or RBI for 8 weeks, and then went into a tiny fluctuation in following months. All of these changes were more obvious in CCR‐treated rats compared to CSI or RBI‐treated rats. Our data showed that CSI or RBI treatment induced COPD in rats, and CCR induced a more stable COPD, which has more complications in COPD patients, such as chronic bronchitis, emphysema, pulmonary hypertension characterized by decreased RVHI.
Decreased membrane cholesterol facilitates depolarizationinduced Ca2+‐sensitization in pulmonary vascular smooth muscle following chronic hypoxia
Authors: Norton Charles E , Naik Jay S , Walker Benjimen R , Resta Thomas C
Published: June 2021

Previous studies support a role for caveolin‐1 (cav‐1) dysfunction in membrane depolarization‐induced Ca2+ sensitization in pulmonary vascular smooth muscle (VSM) from rats exposed to chronic hypoxia (CH). Because caveolar cholesterol content is important in regulation of cav‐1‐protein interactions, we hypothesized that reduced membrane cholesterol contributes to enhanced Ca2+ sensitivity following CH. We therefore examined vasoconstrictor responses to depolarizing concentrations of KCl (30–120 mM) under VSM Ca2+‐clamp conditions following administration of supplemental cholesterol [500 μM ‐ 5 mM methyl‐β‐cyclodextrin (MβCD)], or cholesterol depletion (MβCD, 10 mM) in pressurized endothelium‐disrupted pulmonary arteries (~150 μm diameter) from control and CH (4 wk at 0.5 atm) rats. Consistent with our hypothesis, cholesterol repletion decreased KCl‐dependent constriction in CH arteries and normalized reactivity between groups, while MβCD had no effect in either group. Additionally, CH reduced membrane cholesterol content as determined by filipin fluorescence. However, CH did not affect either arterial cav‐1 levels or caveolar density assessed by western blot and electron microscopy, respectively. We conclude that decreased membrane cholesterol is necessary but not sufficient for enhanced depolarization‐induced pulmonary VSM Ca2+‐ sensitization following CH.
Alterations of Orai, STIM, and TRPC Expression and Store‐ Operated Calcium Entry in Pulmonary Arteries of Monocrotaline‐Induced Pulmonary Hypertensive Rats
Authors: Lin Mo-Jun , Liu Qing , Liu Xiao-Ru , Wang Rui-Xing , Liu Cheng , Sham James S.K.
Published: June 2021

Pulmonary hypertension (PH) is associated with alterations in Ca2+ homeostasis in pulmonary arterial smooth muscle cells (PASMCs). Previous studies show that store‐operated Ca2+ entry (SOCE) is enhanced in PASMCs of chronic hypoxia‐ and monocrotaline (MCT)‐induced PH rats, and idiopathic PH patients. Since the SOCE pathway is composed of many different proteins and channels, including the sarcoplasmic Ca2+ sensor stromal interaction molecules (STIM), Orai channels, and transient receptor potential channels, we sought to examine the alterations in the expression of these molecular constituents of SOCE in the PASM of MCT‐induced PH rats. Rats developed severe PH and right ventricular hypertrophy within three weeks after a single injection of MCT. Quantitative RT‐PCR found that there was significant increase in the expression of STIM2, Orai1, Orai2, TRPC1, and TRPC4, whereas the expression of STIM1, Orai3, and TRPC6 was unchanged. Unregulation of Orai1, TRPC1, and TRPC4 proteins were also verified by Western blot. Moreover, the time‐course of increase in the expression of STIM2, Orai1, and TRPC1 were similar to that of the increase in SOCE induced PA contraction. These results suggest that multiple components of the SOCE pathways are altered during PH and contribute synergistically to the enhanced SOCE in PASMCs. (This work is supported by NSFC 30670772 and 31171104, FJMU09ZD010, NSF‐Fujian 2010J01173, and R01‐HL075134)
Model of pulmonary hypertension induced by reversible pressure‐overloaded left heart failure in rats
Authors: Chovanec Milan , Herget Jan
Published: June 2021

We focused on pulmonary hypertension induced by left heart failure in rats caused by inserting a polyethylene cannula into the ascending aorta via the left carotid artery.

In experiment A, an obturating cannula was implanted for 1 week (group 1wk, n=7), for 3 weeks (group 3wks, n=6) and for 3 weeks with a 3 weeks recovery period after removal of the cannula (group 3+3wks, n=8). We measured RV/LV+S ratio. We found no difference in heart weight vs. controls in the 1wk and 3+3wks groups. The RV/LV+S ratio (0.39±0.024 vs. 0.27±0.008; p<0.01) was significantly increased in the group 3+3wks compared to controls. In experiment B, we measured pulmonary artery pressure (PAP) in closed‐chest animals. Group N (n=8) were normoxic controls. Group H (n=8) were hypoxic controls. Rats were exposed to normobaric hypoxia (10% O2) for 3 weeks. Mean PAP was significantly elevated in groups 1wk and 3wks compared to normoxic controls (25.0±1.18mmHg and 22.9±0.66mmHg vs. 16.9±0.97mmHg; p<0.01 and p<0.05 respectively) but significantly lower compared to hypoxic controls (25.0±1.18mmHg and 22.9±0.66mmHg vs. 33.4±2.0mmHg; p<0.001 and p<0.0001 respectively).

This is a simple, well tolerated and fully reversible method of inducing pressure‐overloaded left heart failure followed by the significant pulmonary hypertension.

Supported by: GACR 305/05/08/108, GAUK 78007 and Cardiovascular Research Centre 1M510.
AT1A receptor‐mediated blood pressure and renal effects of long‐term infusion of a low dose of angiotensin II in C57BL/6J and AT1a receptor‐knockout mice
Authors: Miguel-Qin Elisa , Li Xiao C. , Ellis Bri , Zhuo Jia L.
Published: June 2021

The blood pressure and renal effects of angiotensin II (Ang II) are most commonly studied in rodents either acutely or short‐term infused with high doses of Ang II. Few if any studies have focused on the long‐term effects of a low dose of Ang II on blood pressure and the kidney. In the present study, a low dose of Ang II (400 ng/kg/day, i.p.) was infused continuously for 12 weeks in C57BL/6J (WT) or AT1a receptor‐knockout mice (AT1a‐KO), treated with or without the AT1 receptor antagonist losartan (10 mg/kg/day, p.o.). Ang II caused moderate and time‐dependent increases in systolic blood pressure (SBP) in WT mice (basal: 110 ± 4; Week 4: 120 ± 4; Week 8: 139 ± 3; and Week 12: 134 ± 3 mmHg, p<0.01 vs. basal), which were blocked by losartan. By contrast, Ang II had no effect on SBP in AT1a‐KO mice. 24 h urine and urinary sodium excretion were lower in WT mice infused with Ang II than AT1a‐KO or Ang II‐infused mice treated with losartan (p<0.05).The heart weight to body weight ratio was higher in Ang II‐infused WT mice than in Ang II‐infused mice treated with losartan or AT1a‐KO mice treated with and without Ang II infusion (p<0.01). The kidney weight to body weight ratio is, however, significantly lower in Ang II‐infused WT mice compared to the other groups of mice (p<0.01). Our data strongly suggests that infusion of Ang II, even at an initially non‐pressor dose, for 12 weeks can still elevate blood pressure and cause cardiovascular and renal injury.
Long‐term interactions between the ACE/Ang II/AT1a receptor axis and the ACE2/Ang(1–7)/Mas receptor axis in wild‐type C57BL/6J and AT1a receptor‐knockout mice
Authors: Ellis Brianne Nicole , Li Xiao C , Miguel-Qin Elisa , Zhuo Jia L
Published: June 2021

The present study tested the hypothesis that long‐term hypertensive and renal effects of angiotensin II (Ang II) are antagonized by the activation of the ACE2/Ang (1–7)/Mas receptor axis in C57BL/6J (WT) and AT1a‐KO mice. An equi‐dose of Ang II, Ang (1–7), or in combination, was infused in WT or AT1a‐KO mice continuously for 12 weeks (800 ng/kg/min, i.p.). In WT mice, Ang II increased systolic blood pressure (SBP) in a time‐dependent manner (Basal: 119 ± 6 vs. Week 12: 150 ± 7 mmHg, p<0.01). Ang (1–7) alone had no effect on SBP (Week 12: 119 ± 3 mmHg, n.s.) or on Ang II‐induce hypertension (Week 12: 146 ± 8 mmHg, n.s. vs. Ang II alone). In AT1a‐KO mice, basal SBP was significantly lower than in WT mice, which was not altered by Ang II. However, Ang (1–7) significantly decreased SBP in AT1a‐KO mice (Basal: 107 ± 4 vs. Week 12: 90 ± 2 mmHg, p<0.01). In the kidney, both Ang II and Ang (1–7) slightly increased 24 hour urine and urinary sodium excretion, and this effect was not altered by combination‐infusion in WT mice. Furthermore, Ang II significantly increased the levels of phosphorylated sodium and hydrogen exchanger‐3 in the renal cortex of WT mice (p<0.01), which was not blocked by co‐administration with Ang (1–7). We therefore conclude that the activation of the ACE2/Ang (1–7)/Mas receptor axis is unlikely to fully counter‐balance the long‐term blood pressure and renal effects induced by the ACE/Ang II/AT1 receptor axis.
Renal and lumber sympathetic nerve activity during the development of hypertension in Dahl‐Salt‐Sensitive rats
Authors: Yoshimoto Misa , Onishi Yuko , Mineyama Naoko , Shirai Mikiyasu , Miki Kenju
Published: June 2021

This investigation documented the changes in renal (RSNA) and lumbar (LSNA) sympathetic nerve activity during the early phase of hypertension development induced by 8% salt loading in Dahl Salt‐Sensitive rats. Male Dahl Salt‐Sensitive rats were chronically instrumented with bipolar electrode for recording RSNA and LSNA and with a telemeter for arterial pressure. Arterial pressure increased sharply during the first 3 days after the onset of 8% salt loading and then continued to increase gradually following from 4th day to 14th day of the salt loading. After the cessation of the salt loading, arterial pressure returned to the pre‐salt loading level. RSNA and LSNA did not change significantly throughout the experimental period relative to the pre‐salt loading level. These observations demonstrate that there was no significant relationship between arterial pressure and RSNA or LSNA during the early phase of hypertension development induced by 8% salt loading in Dahl Salt‐Sensitive rats. JSPS Grant.
The PPAR‐γ agonist Rosiglitazone increases angiotensin‐converting enzyme 2 (ACE2) promoter activity in neurons
Authors: Scroggin Melissa , Pedersen Kim B. , Lazartigues Eric
Published: June 2021

Angiotensin converting enzyme 2 (ACE2) converts angiotensin‐(Ang)‐II to the vasodilator peptide Ang‐(1–7). Our laboratory has previously observed that ACE2 expression and activity in brain regions involved in the central regulation of blood pressure (BP) and volume homeostasis (e.g. SFO, PVN, and RVLM) are reduced in mice with elevated brain Ang‐II levels. Other investigators have shown that Rosiglitazone, a peroxisome proliferator‐activator receptor gamma (PPAR‐γ) agonist, increases ACE2 mRNA in adipocytes. Here we assessed the potential of PPAR‐γ to activate the ACE2 gene promoter. A reporter plasmid containing the human ACE2 proximal promoter sequence was constructed, and luciferase activity was measured after transfection of mouse Neuro‐2a cells in the presence or absence of Rosiglitazone (1 μM) and Ang‐II (100 nM) for 24 hours. Human ACE2 promoter activity increased by 2‐fold (P<0.05) with Rosiglitazone treatment independently of Ang‐II treatment, suggesting that PPAR‐γ may bind the proximal promoter and induce expression of hACE2. On the other hand, our data suggest that Ang‐II regulation of the hACE2 gene expression is not dependent on its proximal promoter. Altogether, we show that PPAR‐γ positively regulates the hACE2 promoter activity, supporting a beneficial role in modulating Ang‐II levels in neurogenic hypertension and in the regulation of volume homeostasis. (Funding: HL093178)
Hypertension, glycemic control and microalbuminuria in Haitian Americans and African Americans
Authors: Cuervo Janelle , Zarini Gustavo G. , Exebio Joel C. , McLean Michael , Huffman Fatma G.
Published: June 2021

This cross‐sectional study investigated the relationship between hypertension (HTN), glycemic control (GC) with microalbuminuria (MAU) in African Americans (AA= 129) and Haitian Americans (HA=137) with type 2 diabetes (T2D). Participants were recruited from multiple sources from Miami‐Dade and Broward Counties, FL. Blood pressure (BP) was measured using an adult size cuff. Glycosylated hemoglobin (A1C) levels were measured from fasting blood samples with the Roche Tina‐quant method. MAU was determined in urine samples by a semiquantitative assay (ImmunoDip). Unadjusted odds ratios indicated that participants with poor GC were 2.6 times more likely to have MAU (P=.001; OR = 2.61, 95% CI 1.50, 4.50) compare to those with good GC. Logistic regression showed that participants with poor GC were 2.3 times more likely to have MAU if they had hypertension compared to those without hypertension (P=.004; OR= 2.37, 95% CI 1.32, 4.25). These findings point out the importance of early detection of MAU in both ethnic groups. Adequate blood pressure control along with glycemic control are needed to prevent and treat diabetes complications. Funding for this research was provided through NIH/NIDDK sponsored grant.
Hyper‐caloric diet induces a hydrogen sulfide‐dependent mechanism in aortic perivascular adipose tissue (PVAT) function in Dahl S rats
Authors: Spradley Frank T , Ho Dao H , Pollock Jennifer S
Published: June 2021

PVAT‐mediated blunting of vasoconstriction (PVAT function) is reduced in some obese rodent models. Dahl salt sensitive rats (Dahl S) are predisposed to cardiovascular disease. We tested the hypothesis that hypercaloric diet (HCD; 59% fat/0.4% NaCl) promotes PVAT dysfunction in Dahl S. At 16 weeks old, PVAT mass was greater following a 4 week HCD compared to normal diet (ND; 14% fat/0.4% NaCl) (6.1±0.3 vs 1.9±0.3 PVAT weight:aorta weight; P<0.05; N=6). Using wire myography, phenylephrine (PE) mediated constriction was less in PVAT‐intact vs PVAT‐removed aortae from HCD Dahl S (62±11% vs 145±10% increase in force; P<0.05; N=5). Endothelium (endo) denudation did not alter PE response in PVAT‐intact aortae from HCD Dahl S. Inhibition of the hydrogen sulfide (H2S) generating enzyme cystathionine γ lyase (PAG; 10mM) increased PE response in PVAT‐intact, endo‐denuded aortae from HCD Dahl S (106±8% vs 74±12% increase in force; P<0.05; N=4). In ND Dahl S, PE response was less in PVAT‐intact compared to PVAT‐removed aortae (90±7% vs 157±9% increase in force; P<0.05; N=6), however endo denudation restored PE response in PVAT‐intact aortae (139±2% increase in force). In conclusion, PVAT from ND Dahl S does not directly modulate vascular smooth muscle tone in endo‐denuded aortae whereas a short‐term HCD elicits a functional response in PVAT from Dahl S via an H2S‐dependent mechanism. Funding: PO1 HL69999 and AHA 10PRE4010001.
Female Spontaneously Hypertensive Rats (SHR) have greater increases in NOS in mesenteric arteries than males
Authors: Zimmerman Margaret Ann , Crislip G. Ryan , Sullivan Jennifer C.
Published: June 2021

Female SHR have greater levels of Ang (1–7) and greater NO production than male SHR. This study tested the hypothesis that infusion of Ang (1–7) increases NO synthase (NOS) activity and expression more effectively in female SHR than in males. 11 week old male and female SHR received minipumps to deliver Ang (1–7) (24 μg/kg/hr; n=3–13). After 2 week, the renal cortex and mesenteric arteries were isolated to assess total NOS activity, NOS1 and NOS3 protein expression. NOS activity and protein expression were similar in the renal cortex of untreated male and female SHR and Ang (1–7) infusion did not alter NOS activity or protein expression in either sex. Similarly, NOS activity and protein expression were comparable in mesenteric arteries from untreated female and male SHR. Ang (1–7) infusion increased NOS activity in mesenteric arteries from female (47±5 to 82±12 pmol/mg, p≤.01) and male SHR (38±3 to 50±6 pmol/mg, p≤.05); however the increase in NOS activity was greater in females. Increased NOS activity was not associated with changes in NOS1 protein expression in either sex, however, Ang (1–7) increased NOS3 (endothelial NOS) protein expression in females (0.6±0.05 to 0.8±0.08 densitometric units, p≤.01), with no effect in male SHR. In conclusion, female SHR more sensitive to tissue specific Ang (1–7) mediated increases in NOS activity and expression, which may contribute to lower blood pressure in female SHR.
Toll‐Like Receptor 4 Contributes to Hypertension and Endothelial Dysfunction Produced By Angiotensin II
Authors: Palvia Vijay , Pyle Chelsea , Mezzetti Erin , Chen Xunsheng , Didion Sean
Published: June 2021

We have previously found that C3H/He mice are a strain of mice that is resistant to endothelial dysfunction produced by Angiotensin II (Ang II). Interestingly, C3H/He mice carry a point mutation in the Toll‐Like Receptor 4 (TLR4) gene that results in defective TLR4‐mediated signaling. The goal of this study was to further explore the potential role of TLR4 in the hypertension and endothelial dysfunction produced by Ang II. C57Bl/6 (TLR4+/+ strain) and C57Bl/10ScN mice (a strain that carries a null‐mutation for the TLR4 gene) were infused with either vehicle or Ang II (1000 ng/kg/min) for 14 days. Baseline blood pressure was similar in C57Bl/6 and C57Bl/10ScN and on Day 14 of vehicle‐infusion. Ang II‐infusion produced hypertension in both C57Bl/6 and C57Bl/10ScN mice, however the degree of hypertension was significantly greater in C57Bl/6 than C57Bl/10ScN mice (164±6 vs. 147±9 mmHg, respectively). Acetylcholine produced concentration‐dependent relaxation that was similar in carotid arteries from vehicle‐infused C57Bl/6 and C57Bl/10ScN mice. In contrast, responses to acetylcholine were markedly impaired in Ang II‐infused C57Bl/6 mice. Responses to acetylcholine in Ang II‐infused C57Bl/10ScN mice were similar to their vehicle‐infused counterparts. Taken together, these findings demonstrate that TLR4 expression contributes to the hypertension and endothelial dysfunction produced by Ang II.
Role of ENaC and of the Na/K pump on the Hypertonicity‐induced inhibition of Na Transport in Cystic Fibrosis Human Bronchial Epithelial Cells
Authors: Rasgado-Flores Hector , Ngansop Thierry , Piennette Paul , Gallegos Kevin , Bridges Robert J
Published: June 2021

Introduction

Hypertonic saline (HS) inhalation produces surprisingly long lasting benefits to Cystic Fibrosis (CF) patients. We have found that exposure to hypertonic challenge (HC) solutions produce long‐lasting inhibitions of the transepithelial short‐circuit current (ISC) in primary cultures of human bronchial epithelial (HBE) cells from CF donors.

Aims

To determine if the HS‐induced inhibition of ISC is due to inhibition of the epithelial Na+ channels (ENaC) and/or the basolateral Na/K ATPase.

Methods

HBE cells from CF were grown on Transwell inserts (air liquid interface) and were mounted on Ussing chambers to perform trans‐epithelial impedance analysis and measure transepithelial ISC, resistance (Rt), capacitance (Ct) and Conductance (Gt) The putative role of ENaC and of the Na/ATPase on the HC‐induced inhibition of the ISC was studied by permeabilizing the apical or basolateral membranes with Nystatin.

Results

i) Exposure to apical or basolateral HC‐NaCl or HC‐mannitol inhibited ISC. ii) Exposure to HC‐solutions induced cell shrinkage as indicated by a reduction in CT.; iii) Neither activity of the Na/K ATPase nor the ENaC was absolutely required for the HC‐induced inhibition of ISC.

Conclusions

Cell shrinkage, together with a likely increase in the intracellular Na+ concentration inhibit transepithelial Na transport (ISC). Both, the ENaC and the Na/K ATPase play a role in this inhibition.
Discovery of novel small molecule CFTR inhibitor through structural modification of compound from Thai plant: Mechanism and Anti‐diarrheal efficacy
Authors: Sawasvirojwong Sutthipong , Suksamrarn Sunit , Chatsudthipong Varanuj , Muanprasat Chatchai
Published: June 2021

Inhibition of Cystic fibrosis transmembrane conductance regulator (CFTR) is proposed as a promising therapeutic approach for cholera, one of the important health problems worldwide. To identify novel class of CFTR inhibitors, several natural compounds were structurally modified and tested for CFTR inhibitory effect in Fisher rat thyroid (FRT) cells stably expressing human CFTR. Among test compounds, compound 130 exhibited the highest potency (IC50 ~10 μM). It inhibited CFTR‐mediated apical chloride current stimulated by forskolin, CPT‐cAMP and apigenin. CFTR inhibitory effect of compound 130 was reversible and not associated with cytotoxicity. Electrophysiological analysis indicated that compound 130 is a CFTR pore blocker. Similarly, compound 130 inhibited cAMP and cholera toxin‐induced chloride secretion across T84 cell monolayers without changing intracellular cAMP level. Interestingly, compound 130 inhibited calcium‐activated chloride channel with similar potency. Intraluminal injection of compound 130 blocked cholera toxin‐induced intestinal fluid secretion by ~80% in mouse closed‐loop models. In mouse open‐loop cholera models, oral administration of compound 130 prevented intestinal fluid secretion was by ~80%. This study reveals a new class of CFTR inhibitors, which holds the promise for treatment of infectious secretory diarrhea.

This work was supported by the Thailand Research Fund and the Office of the Higher Education Commission and Mahidol University under the National Research Universities Initiative.