Search

Hypertension is a high risk of heart disease and stroke, which is caused by vasoconstrictive arteries due to angiotensin II binds to angiotensin II type 1 receptor (AT1R). Treatment of hypertension using the drugs angiotensin receptor blockers (ARBs) causes side effects of headaches, constipation, and diuretics. Phenolic compounds (10-gingerol, 8-gingerol, 6-gingerol) from red ginger (Zingiber officinale var. rubrum) were used for hypertensive herbal medicines. This study aims to predict the potency of 10-gingerol, 8-gingerol, 6-gingerol as AT1R antagonist by bioinformatics approach. This research was conducted using physicochemical properties, Pa test, pharmacokinetic test, and molecular docking of the three gingerol compounds and Losartan as drug control. The results show that 10-gingerol, 8-gingerol, 6-gingerol have good oral bioavailability, good vasodilator potential (Pa >7), hepatoprotective potential, vasoprotective potential, and antioxidant potential. Based on pharmacokinetic absorption, distribution, and excretion test, the three gingerol compounds showed higher results compared to the Losartan. The toxicity of the gingerol compounds is low, not hepatotoxic, whereas Losartan is hepatotoxic. Molecular docking showed that the three gingerol compounds and the Losartan were on one side of the binding to AT1R. The conclusion of this study is red ginger has potency as a candidate for oral drug hypertension. [ABSTRACT FROM AUTHOR]

Low intensity pulsed ultrasound (LIPUS) has been shown to enhance bone and cartilage regeneration from stem cells. Gene expression of angiotensin II type 1 (AT1) receptor can be increased in LIPUS-treated osteoblasts. The AT1 receptor is a known mechanoreceptor in cardiomyocytes. It suggests that LIPUS may enhance cardiomyogenesis via mechanotransduction by increasing AT1 expression. Murine embryonic stem cells (ESCs) were treated daily by 10-min 1MHz LIPUS at spatial-average temporal-peak acoustic intensities of 30 mW/cm2 and 300 mW/cm2 in both continuous and pulsed wave (20% duty cycle) for 10 days. Polymerase chain reaction (PCR), immunocytochemistry, and beating rate were used to evaluate the cardiac viability quantitatively. After the treatment of LIPUS, beating rate of contractile areas and cardiac gene expression, such as α- and β-myosin heavy chain, were improved. Furthermore, no deleterious effects to the development of cardiac proteins were observed. All results suggest that LIPUS stimulation has the capacity of enhancing cardiomyogenesis from embryonic stem cells. With the benefit and the ease in incorporating LIPUS into various culture platforms, LIPUS has the potential to produce cardiomyocytes for clinical use in the future. [ABSTRACT FROM AUTHOR]

Angiotensin Converting Enzyme Inhibitors (ACEI) and Angiotensin II Receptor Blockers (ARB) are two common medication classes used for heart failure treatment. The ADAHF (Automated Data Acquisition for Heart Failure) project aimed at automatically extracting heart failure treatment performance metrics from clinical narrative documents, and these medications are an important component of the performance metrics. We developed two different systems to detect these medications, rule-based and machine learning-based. The rule-based system used dictionary lookups with fuzzy string searching and showed successful performance even if our corpus contains various misspelled medications. The machine learning-based system uses lexical and morphological features and produced similar results. The best performance was achieved when combining the two methods, reaching 99.3% recall and 98.8% precision. To determine the prescription status of each medication (i.e., active, discontinued, or negative), we implemented a SVM classifier with lexical features and achieved good performance, reaching 95.49% accuracy, in a five-fold cross-validation evaluation. [ABSTRACT FROM AUTHOR]

An abstract of the article "Effect of high salt diet on expression of antioxidative enzymes, hypoxia inducible factor 1 alpha & cyclooxygenase 1 and 2 in blood vessels of Sprague-Dawley rats" by A. Ćosi Č, S. Novak, M. Mihalj and Z. Mihaljević is presented.

Genetic studies have led to the identification of proteins playing a crucial role in glomerular slit-diaphragm signaling and maintenance of podocyte integrity. Particularly, the gene encoding transient receptor potential canonical channel 6 (TRPC6) was identified as the genetic basis for an autosomal dominant form of focal segmental glomerulosclerosis (FSGS). A key role for podocytes in the pathogenesis of proteinuric diseases has been established since the injury of these cells leads to proteinuria and foot process effacement. Interstitial angiotensin II (Ang II) is found to be a key mediator of renal inflammation and fibrosis in chronic nephropathies. It was shown that expression of Ang II and its receptors (ATRs) is increased in patients with progressive glomerulopathies; what is more, Ang II application can increase intracellular calcium, and members of the TRPC-family channels emerged as prime candidates for this raise. The goal of this research was to define the signaling mechanisms mediating the effect of Ang II on TRPC6 channels in the podocytes and to study the potential capabilities of ATRs inhibitors in the treatment of FSGS. To address this aim we established a new approach allowing to measure ion channels activity and calcium concentration changes in the freshly isolated decapsulated glomeruli. We examined the effects of Ang II on intracellular Ca2+ concentrations in intact podocytes of the rat glomeruli. Changes in intracellular Ca2+ stimulated by 100 nM and up to 10 µM of Ang II in the presence or absence of thapsigargin or 100 µM TRPC inhibitor 2-APB were measured in Fura-2AM loaded podocytes of the intact glomeruli. Depletion of internal Ca2+ stores with thapsigargin did not affect cell activation by Ang II, but 2-APB totally blocked calcium flux. This therefore allows hypothesizing that TRPC channels in the podocytes mediate calcium influx in response to Ang II. Western blotting and IHC staining revealed that TRPC1, 3 and 6 are expressed in the Sprague Dawley rat glomeruli. Single channel electrophysiological analysis with patch-clamp demonstrated that 100 nM Ang II acutely activates native TRPC-like channels in the podocytes, as well as TRPC6 channels transiently overexpressed in CHO cells together with the ATR1; the detected effect was mediated by changes in the channel open probability. The ability of podocytes to precisely regulate intracellular Ca2+ plays a central role in glomerular diseases, therefore, manipulating Ca2+ levels by inhibiting TRPC channels or their activators may be a useful strategy for treating patients with FSGS. In this study we provide evidence of Ang II-dependent activation of TRPC6 channels in podocytes, which might play a significant role in the development of kidney diseases. [ABSTRACT FROM AUTHOR]

Angiotensin 1-7 (Ang1-7) has diuretic/natriuretic properties at the kidney. There is evidence that this response is due to a counter-regulation of the anti-diuretic/anti-natriuretic actions of Angiotensin II and is therefore dependant on the level of activation or suppression of the endogenous renin-angiotensin system (RAS). This study investigated whether the excretory responses to intrarenal Ang1-7 are altered in Deoxycorticosterone Acetate (DOCA) salt hypertensive rats where the RAS is known to be depressed. Male Wistar rats received two s.c. injections weekly of DOCA(15mg/kg) in arachis oil (2ml/kg) and 9% NaCl/2% KCl drinking water for four weeks, one week following unilateral nephrectomy performed under 5% isoflurane (0.5L/min O2) induction/2% (0.2L/min O2) maintenance. Prior to the terminal experiments animals were placed in metabolic cages to determine baseline excretory function. Anaesthesia was induced using 1 ml/kg body weight sodium pentobarbital i.p. The femoral artery was cannulated, to monitor mean arterial pressure (MAP), and vein, for infusion of saline at 3ml/h containing inulin. The left ureter was cannulated for urine collection and a small cannula inserted into the cortico-medullary border for the infusion of saline and Ang1-7 (6x10-6M) at 1 ml/h. After 1.5h, 20 min clearances were taken, two before and two 50 mins after the start of the Ang1-7 infusion. The rats were killed at the end of the experiment by anaesthetic overdose. Data, means±SEM were subjected to t-tests and significance taken at P<0.05. DOCA treated group (n=6) had a higher GFR than the control group (n=7), at3.3±0.2 vs. 1.1±0.06ml/min/kg respectively, and a higher urine volume (UV), at 131.5±11.1 vs. 29.5±3.6µl/min respectively. Sodium excretion values were also higher for the DOCA treated group compared to the control group, with absolute sodium excretion (UVNa) values of 29.0±2.1 vs. 1.42±0.09 µmol/min respectively, and fractional sodium excretion values(FENa) of 5.4±0.4 vs. 0.9±0.05% respectively. Ang1-7 had no effect on blood pressure, at 111±5 mmHg for control rats and 162±4 mmHg for DOCA rats, or GFR, at 4.4±0.4ml/min/kg and following Ang1-7 infusion 5.2±0.5ml/min/kg for control rats and for DOCA rats 9.1±2.2ml/min/kg and 10.9±2.8ml/min/kg before and after infusion respectively. In control rats, UV significantly increased (P<0.05) from 100.9±6.9 to 139.1±4.5 µl/min, UVNa, from 16.0±1.3 to 24.3±1.0 µmol/min and FENa by 2.3±0.5 to 2.9±0.5%. In the DOCA model these responses to Ang1-7 were completely blunted, with UV, 163.5±35.7µl/min, UVNa, 39±11 µmol/min and FeNa, 2.4±0.07% and following Ang1-7 infusion UV, 145.4±47.7µl/min, UVNa, 29.4±8.5µmol/min, and FENa, 1.5±0.2%. These findings suggest that the suppression of the RAS in the DOCA model of hypertension interferes with the diuretic/natriuretic response seen in normal animals to intra renal Ang1-7 infusion. [ABSTRACT FROM AUTHOR]

There is increasing evidence that angiotensin II (Ang II) is associated with the cardiac electrical remodeling and thus the occurrence of ventricular arrhythmias under pathological conditions. Human ether-a-go-go-related gene (hERG) encodes the pore forming subunit of the channel underlying IKr, which is crucial for the repolarisation of cardiac action potentials. Our previous study has shown that Ang II produces an acute inhibitory effect on IKr/hERG currents via AT1 receptors in guinea pig ventricular myocytes. The present study was designed to investigate the post-transcription regulation of hERG channel protein by chronic stimulation of AT1 receptors in heterologous expression system. An HEK 293 cell line stably expressing hERG channels was established and human AT1 receptor was transiently co-transfected. Western-blot analysis showed that Ang II decreased the abundance of mature hERG protein (155-kDa) in a time- and dose-dependent manner without affecting the level of immature hERG protein (135-kDa). The relative intensity of mature 155-kDa band as control was 68 ± 4% after incubation of Ang II at 100 nM for 24 hours (P<0.0, n=6). Values are means ± S.E.M. of n experiments, compared by two-tailed Student's t test. To investigate the effects of Ang II on degradation of mature hERG channels, we blocked forward trafficking with a Golgi transit inhibitor brefeldin A (BFA, 10 μM). Ang II significantly enhanced the time-dependent reduction of mature hERG channels. A proteasomal inhibitor lactacystin (5 μM) significantly inhibited Ang II-mediated reduction of the mature protein (from 67 ± 4% to 89 ± 3%, P<0.05, n=3), but the lysosomal inhibitor bafilomycin A1(1 μM) had no significant effect on the role of Ang II. It indicated that Ang II accelerated channel protein degradation, primarily through the proteasome pathway. The protein kinase C inhibitor bisindolylmaleimide I antagonized the reduction of mature 155-kDa proteins by Ang II, suggesting that the effect of Ang II was mediated by intracellular PKC signaling pathway. In conclusion, the chronic incubation of Ang II reduced the mature hERG channel protein by accelerating channel degradation through a PKC pathway. The findings suggest a potential mechanism by which elevated levels of Ang II may be involved in the hERG channel remodeling in heart diseases. [ABSTRACT FROM AUTHOR]

An abstract of the article "The development of Angiotensin II-induced hypertension during various salt intakes in Cre/lox conditional knockout mice for bradykinin receptors in distal tubule" by L. Kopkan is presented.

An abstract of the article "Angiotensin II as a novel regulator of urothelial and bladder function" by L. Adjei, J. Li, and C. Wu is presented.

Overactivation of β-adrenoceptors induced by isoproterenol (ISO) treatment causes cardiac remodeling and vascular dysfunction. It is known that angiotensin II via AT1 receptor and aldosteronevia mineralocorticoid receptor (MR) partially mediates the cardiac injury induced by ISO, including: myocardial hypertrophy and fibrosis, oxidative stress and inflammation. In the present study we tested the hypothesis that signaling pathways activated by AT1 and/or MR receptors are involved in the impairment of nitric oxide (NO) bioavailability induced by ISO treatment. Male Wistar rats were treated with ISO (0.3 mg/kg/day, s.c.) or vehicle (CT) and co-treated or not with the AT1 antagonist losartan (LOS, 40 mg/kg/day, p.o.) or MR antagonist spironolactone (SPI, 200 mg/kg/day, p.o.) for one week. In isolated aortic rings with endothelium (n=6-8 in each group), maximal response (Rmax) evoked by phenylephrine (Phe, 1ηM- 10µM) was enhanced in ISO-treated rats (CT= 6.8 ± 0.4 vs. ISO= 8.8 ± 0.5 mN/mm; p<0.05; n=6-8). LOS co-treatment did not modify this contractile hyperresponsiveness (ISO/LOS= 8.3 ± 0.2 mN/mm; n=6; p<0.05 vs. ISO), while SPI abolished this effect (ISO/SPI= 6.3 ± 0.3 mN/mm; n=8; p<0.05 vs. ISO). The NO synthase (NOS) inhibitor L-NAME (100 µM) enhanced the Rmax to Phe in aortas from all groups, abolishing differences among then. The superoxide dismutase (SOD, 150 U/mL) reduced Rmax to Phe only in ISO and ISO/LOS groups. This result suggests an enhanced participation of superoxide anion on aortic contractile response of ISO-treated rats that is normalized by SPI but not altered by LOS. Fluorescences to hydroethidine (DHE, 2 µM) and to diaminofluorescein-2 (DAF-2, 8 µM) were used to quantify reactive oxygen species and NO, respectively (n=5-6 in each group). Elevated DHE (+44%) and reduced DAF-2 (-60%) fluorescence was observed in aortas from ISO-treated rats; SPI co-treatment, but not LOS, normalized it. Incubation with L-NAME significantly reduced the fluorescence to DHE (-33%) in aortic slices of ISO group. Protein expression was evaluated in aortic homogenates (n=6-8 in each group) and no significant changes in SOD-1, -2 and -3 protein expression among groups were observed. On the other hand, eNOS protein expression was significantly enhanced by ISO treatment (+56%) whilst phosphorylation of eNOS at Ser1177 (normalized by total eNOS content) was reduced (-43%). Neither LOS nor SPI modified this ISO effect. In conclusion, data suggest that ISO treatment could enhance vascular contractility due to high superoxide anion production via uncoupled eNOS and reduced NO availability. These vascular effects seem to be mediated by MR but not by AT1 receptor. [ABSTRACT FROM AUTHOR]

High blood pressure (hypertension) indicates the deterioration of the set points of metabolic fitness and is one of the most frequent metabolic risk factors in Western countries. Pharmacological inhibition of angiotensin 2 (ANGII) by ACE inhibition action may have undesirable side effects, particularly, in the situation when one wants to exploit the sympatholytic and angiogenic benefits of physical therapy. Limited studies investigated ANGII levels related to exercise intensity and duration, but it seems to be that there is only an increase above with exercise intensity above the anaerobic threshold. The aim of this research is to detect changes in human ANGII levels after exercises of different intensities at or above the anaerobic threshold. On three separate occasions fit healthy male subjects (n=10, age: 29.6±2.1 year, length: 180.9±7.6 cm, mass: 76.1±5.6 kg) performed a maximal incremental exercise tests, a 12-minutes test at an intensity were they reached their aerobic threshold intensity and a 3-minutes test their ventilator compensation point intensity. Expired air was measured breath-by-breath, blood samples were taken before and 0, 3, 6 and 12 minutes after exercise and subject were screened for the ACE I-allele polymorphism. Blood was measured on lactate concentration and serum on ANGII levels. Values are means ± S.E.M. Direct after the 3-minutes cycling test there was a 1.8- fold increase in ANGII serum levels compared to resting levels (paired T-Test, 3.20±0.83 vs. 5.75±0.81 pg/mL, p=0.001) and after the 12-minutes test there was a 1.2-fold increase (paired T-Test, 4.4±1.47 vs. 5.5±1.30 pg/mL, p=0.24). ANGII levels were not affected after the maximal exercise test. 12 minutes after maximal exercise subjects with the ID/DD genotype had a significant lower ANGII serum level compared to subjects with the II genotype (ANOVA, 1.7±1.0, 9.6±5.5, p<0.05). ANGII levels were not correlated with blood lactate levels. ANGII could be detected after a non-maximal high intensity exercise. The data indicate that variability in the response of the major vasoconstrictor, ANGII, in serum after exercise is related to the ACE genotype dependent but not blood lactate. [ABSTRACT FROM AUTHOR]

Angiotensin (Ang) II, a vasoactive peptide and one of the main components of the rennin-angiotensin system (RAS), plays a very significant role in regulating blood pressure and may drive in part, the progression of pulmonary arterial hypertension (1). PAH is caused by functional and structural modifications in the pulmonary vasculature, resulting in increased resistance. This remodeling is accompanied by endothelial dysfunction, smooth muscle cell activation and recruitment of circulating progenitor cells (2). PAH contributes to the development of cardiovascular complications and despite advances in antihypertensive drug therapy, uncontrolled hypertension is still prevalent globally (3). Ang 1-7, an ACE2 (Angiotensin Converting Enzyme 2)-derived metabolite of Ang II exerts cardioprotective effects and is regarded as a potential antagonist of Ang II (1, 4). Using methods described previously (5), we assessed the mechanism of Ang II--induced Ca2+ signalling in acutely isolated rat pulmonary arterial smooth muscle cells (PASMCs) and the effect of Ang 1-7 on these responses. Extracellular application of 3µM Ang II evoked a robust Ca2+ transient in acutely isolated rat PASMCs, the Fura-2 fluorescence ratio (F340/F380) increasing from 0.44±0.01 to 1.19±0.05 (n=67). Ang II-evoked Ca2+ transients were abolished by the AT1R blocker Losartan (10µM; F340/F380 ratio increasing from 0.68±0.05 to 0.81±0.08 (n=9)), but remained unaffected by the AT2R blocker PD123319 (50µM; F340/F380 ratio increasing from 0.55±0.04 to 1.36±0.06 (n=9)). Surprisingly, although Ang 1-7 (3µM) had little effect on intracellular calcium in its own right, it significantly attenuated Ang II-evoked Ca2+ transients; Ang II increasing the F340/F380 ratio from 0.46±0.04 to 0.72±0.07 (n=23) in the presence of Ang1-7. We conclude that Ang II induces Ca2+ signals in rat PASMCs by activating AT1Rs and thus induces voltage-gated Ca2+ influx via L-type Ca2+ channels and SR Ca2+ release via RyRs, and in a manner that is be opposed by Ang 1-7. [ABSTRACT FROM AUTHOR]

Background: Angiotensin II (AngII) acts via several tissues, including the brain to exert its well established roles in the regulation of blood pressure (BP) and fluid and electrolyte regulation. Manipulation of brain AngII can also induce metabolic changes including lean phenotype and increased metabolic rate possibly via modulation of the sympathetic nervous system. These actions are mediated via activation of the AngII type 1A receptor (AT1AR). In addition, chronic low dose infusion of Ang II induces hypertension via activation of the AT1AR. Whilst the involvement of AT1AR in specific cells of the kidney has been demonstrated in AngII-dependent hypertension it is not clear whether other tissues are involved. The present study aimed to investigate whether targeted deletion of AT1ARs from the catecholaminergic cells affects the baseline metabolic parameters and blood pressure (BP) and the response to sustained infusion of AngII. Methods: All experiments were approved by the University of Melbourne Animal Experimentation Ethics Committee in accordance with guidelines of the Australian National Health and Medical Research Council. Mice (C57Bl/6 background) with cell-selective deletion of the AT1AR from catecholaminergic cells were generated by crossing AT1AR floxed (AT1ARfl/fl) mice with mice expressing crerecombinase (Cre) under the control of the tyrosine hydroxylase (TH) promoter. Two different genotypes AT1ARfl/fl;THCre+/- (knockouts) and AT1ARfl/fl;TH-Cre-/- (controls) were used in this study. In vitro autoradiography was performed to confirm the loss of AT1R binding from catecholaminergic cells. All surgical procedures were performed under surgical anesthesia (loss of pedal withdrawal reflex) using either isoflurane delivered by a gas mask (~2% in oxygen) or ketamine/xylacine i.p. (75 mg/kg:10 mg/kg). All animals received a long-acting, non-steroidal anti-inflammatory agent at the start of the surgical procedure (caroprofen 5 mg/kg). Telemetry devices were used to record baseline BP and heart rate (HR). For the metabolic studies, mice were housed individually in metabolic cages with free access to food and water. After 1 day acclimatization 24 hour urine output and food and water intake were recorded. AngII-dependent hypertension was induced by subcutaneous implantation of mini-osmotic pumps designed to infuse Ang II (500 ng/kg/min) for 4 weeks. Results: AT1R binding was completely absent in the adrenal medulla and thoracic sympathetic ganglia of the AT1AR fl/fl;TH-Cre+/- mice. Basal systolic BP and HR were not different between the groups (mean±SEM; 109± 1mmHg vs. 108 ± 2 mmHg and 553± 10 bpm vs. 573 ± 10 bpm). Body weight, water intake, and 24 h urine volumes were also not different between groups. Infusion of Ang II in AT1ARfl/fl;TH-Cre-/- induced a gradual pressor response that was increased above baseline by day 5 of infusion. The maximal change in BP occurred at day 13. After day 17 BP gradually decreased toward baseline. The trajectory of BP increase was less in the AT1A fl/fl;TH Cre+/- mice throughout the infusion with a significant decrease in the maximal response at day 13 of infusion (150± 3 mmHg vs. 133 ± 2 mmHg; P<0.05). The reduced pressor response was associated with reduced fluid and electrolyte retention, reduced activation of the sympathetic nervous system and loss of superoxide formation in key brain cardiovascular nuclei. Conclusions: AT1AR knockout from catecholaminergic cells does not elicit changes in metabolic state, baseline systolic BP or HR but expression of the receptor by these cells is essential for the full development of AngII hypertension. [ABSTRACT FROM AUTHOR]

The renin-angiotensin system (RAS) is a key regulator of blood pressure (BP), with angiotensin II (ang II) acting as a major effector molecule via its receptors which are broadly expressed in a variety of tissues. Previous and ongoing work from our lab has demonstrated the significance of the type 1 angiotensin receptor in the kidney for BP homeostasis. We have taken the approach of gene-targeting in mice to study the role of the AT1A receptor in BP regulation and hypertension pathogenesis. Mice completely deficient in AT1A receptors had profound reductions (>20 mm Hg) in systolic blood pressure. Following this, we next used a kidney cross-transplantation approach to identify the kidney as a tissue with a distinct role in BP regulation by the RAS. Kidney AT1A KO mice had lower baseline BPs and were resistant to angiotensin II hypertension. Our more recent studies have investigated the function of the AT1A receptor in BP control in individual cell lineages in order to dissect the role of the RAS in specific regions of the kidney. To accomplish this, we utilized a cre-loxp approach for cell-specific gene targeting using a mouse line we generated with a conditional Agtr1a allele. We have systematically examined the role of the AT1A receptor in BP regulation in the renal proximal tubule, distal nephron and renal vasculature. Our studies have identified critical segments in the kidney for baseline blood pressure homeostasis, salt sensitivity, and regulation of hypertension. Together, our data suggest that type 1 angiotensin receptors in the kidney play a complex role in the integrated control of blood pressure. [ABSTRACT FROM AUTHOR]