Displaying publications 21 - 40 of 45 in total

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  1. Rathore HA, Munavvar AS, Abdullah NA, Khan AH, Fathihah B, NurJannah MH, et al.
    Auton Autacoid Pharmacol, 2009 Oct;29(4):171-80.
    PMID: 19740088 DOI: 10.1111/j.1474-8665.2009.00445.x
    1 A raised cardiac workload activates neurohormones which will increase muscle mass and shift contractility to the right along the Frank-Starling curve. 2 This study examined the interaction between the SNS and RAS in contributing to vascular responsiveness following the development of cardiac hypertrophy due to aortic banding. 3 Sprague Dawley rats (180-200 g) were assigned to one of six groups; Normal, Sham-operated, Aortic Banded (AB), Aortic Banded treated with losartan (ABLOS), Aortic Banded treated with 6-hydroxydopamine (ABSYMP) and Aortic banded treated with both losartan and 6-hydroxydopamine (ABSYMPLOS). A constricting band was placed around the supra renal aorta on day zero with drug treatment from day 37 to day 44. Vasopressor responses to noradrenaline, phenylephrine, methoxamine and angiotensin II were measured on day 45. 4 The magnitudes of the MAP responses to all vasoactive agents, expressed as percentage changes, were similar in Normal and Sham groups, but reduced in the AB group. ABLOS group showed attenuated response to ANGII whereas all responses were enhanced in the ABSYM group. 5 A positive interaction between the two systems was observed with alpha(1A)-adrenoceptors identified as a major component of SNS and AT(1) receptors of RAS to induce vasopressor effects.
    Matched MeSH terms: Renin-Angiotensin System/physiology*
  2. Balakumar P, Jagadeesh G
    Cell Signal, 2014 Oct;26(10):2147-60.
    PMID: 25007996 DOI: 10.1016/j.cellsig.2014.06.011
    Ang II, the primary effector pleiotropic hormone of the renin-angiotensin system (RAS) cascade, mediates physiological control of blood pressure and electrolyte balance through its action on vascular tone, aldosterone secretion, renal sodium absorption, water intake, sympathetic activity and vasopressin release. It affects the function of most of the organs far beyond blood pressure control including heart, blood vessels, kidney and brain, thus, causing both beneficial and deleterious effects. However, the protective axis of the RAS composed of ACE2, Ang (1-7), alamandine, and Mas and MargD receptors might oppose some harmful effects of Ang II and might promote beneficial cardiovascular effects. Newly identified RAS family peptides, Ang A and angioprotectin, further extend the complexities in understanding the cardiovascular physiopathology of RAS. Most of the diverse actions of Ang II are mediated by AT1 receptors, which couple to classical Gq/11 protein and activate multiple downstream signals, including PKC, ERK1/2, Raf, tyrosine kinases, receptor tyrosine kinases (EGFR, PDGF, insulin receptor), nuclear factor κB and reactive oxygen species (ROS). Receptor activation via G12/13 stimulates Rho-kinase, which causes vascular contraction and hypertrophy. The AT1 receptor activation also stimulates G protein-independent signaling pathways such as β-arrestin-mediated MAPK activation and Src-JAK/STAT. AT1 receptor-mediated activation of NADPH oxidase releases ROS, resulting in the activation of pro-inflammatory transcription factors and stimulation of small G proteins such as Ras, Rac and RhoA. The components of the RAS and the major Ang II-induced signaling cascades of AT1 receptors are reviewed.
    Matched MeSH terms: Renin-Angiotensin System/physiology*
  3. Gupta G, Dahiya R, Singh Y, Mishra A, Verma A, Gothwal SK, et al.
    Chem Biol Interact, 2020 Feb 01;317:108975.
    PMID: 32032593 DOI: 10.1016/j.cbi.2020.108975
    In patients with acute kidney injury progressively converting into chronic kidney disease (CKD), proteinuria and high blood pressure predict progression to end-stage renal disease (ESRD). Although, Renin-angiotensin-aldosterone system (RAAS) regulates blood pressure and kidney disease through both direct and indirect mechanisms. RAAS blockers that act at the level of angiotensin or lower in the cascade can cause compensatory increases in the plasma renin and angiotensin II level. Here, in this review article, we are exploring the evidence-based on RAAS blockade action releases of aldosterone and hypothesizing the molecular mechanism for converting the acute kidney injury into chronic kidney disease to end-stage renal disease.
    Matched MeSH terms: Renin-Angiotensin System/drug effects*
  4. Agarwal P, Agarwal R
    Expert Opin Ther Targets, 2018 07;22(7):629-638.
    PMID: 29883239 DOI: 10.1080/14728222.2018.1486822
    INTRODUCTION: Disturbances of extracellular matrix (ECM) homeostasis in trabecular meshwork (TM) cause increased aqueous outflow resistance leading to elevated intraocular pressure (IOP) in glaucomatous eyes. Therefore, restoration of ECM homeostasis is a rational approach to prevent disease progression. Since renin-angiotensin system (RAS) inhibition positively alters ECM homeostasis in cardiovascular pathologies involving pressure and volume overload, it is likely that RAS inhibitors reduce IOP primarily by restoring ECM homeostasis. Areas covered: Current evidence showing the presence of RAS components in ocular tissue and its role in regulating aqueous humor dynamics is briefly summarized. The role of RAS in ECM remodeling is discussed both in terms of its effects on ECM synthesis and its breakdown. The mechanisms of ECM remodeling involving interactions of RAS with transforming growth factor-β, Wnt/β-catenin signaling, bone morphogenic proteins, connective tissue growth factor, and matrix metalloproteinases in ocular tissue are discussed. Expert opinion: Current literature strongly indicates a significant role of RAS in ECM remodeling in TM of hypertensive eyes. Hence, IOP-lowering effect of RAS inhibitors may primarily be attributed to restoration of ECM homeostasis in aqueous outflow pathways rather than its vascular effects. However, the mechanistic targets for RAS inhibitors have much wider distribution and consequences, which remain relatively unexplored in TM.
    Matched MeSH terms: Renin-Angiotensin System/drug effects
  5. Ahmad N, Jamal R, Shah SA, Gafor AHA, Murad NAA
    Curr Diabetes Rev, 2019;15(4):263-276.
    PMID: 29984662 DOI: 10.2174/1573399814666180709100411
    BACKGROUND: The association of polymorphisms in the renin-angiotensin-aldosterone system candidate genes, namely Angiotensin-Converting Enzyme (ACE) Insertion/Deletion (I/D), Angiotensinogen (AGT) M235T and Angiotensin II Receptor Type 1 (AGTR1) A1166C with Diabetic Nephropathy (DN) has been studied for decades.

    OBJECTIVE: This meta-analysis aimed to assess the updated pooled effects of these polymorphisms with DN among Asian populations with type 2 diabetes mellitus.

    METHODS: The PubMed electronic database was searched without duration filter until August 2017 and the reference list of eligible studies was screened. The association of each polymorphism with DN was examined using odds ratio and its 95% confidence interval based on dominant, recessive and allele models. Subgroup analyses were conducted based on region, DN definition and DM duration.

    RESULTS: In the main analysis, the ACE I/D (all models) and AGTR1 A1166C (dominant model) showed a significant association with DN. The main analysis of the AGT M235T polymorphism did not yield significant findings. There were significant subgroup differences and indication of significantly higher odds for DN in terms of DM duration (≥10 years) for ACE I/D (all models), AGT M235T (recessive and allele models) and AGTR1 A1166C (recessive model). Significant subgroup differences were also observed for DN definition (advanced DN group) and region (South Asia) for AGTR1 A1166C (recessive model).

    CONCLUSION: In the Asian populations, ACE I/D and AGTR1 A1166C may contribute to DN susceptibility in patients with T2DM by different genetic models. However, the role of AGT M235T needs to be further evaluated.

    Matched MeSH terms: Renin-Angiotensin System/genetics*
  6. Singh Y, Gupta G, Satija S, Negi P, Chellappan DK, Dua K
    Dermatol Ther, 2020 Jul;33(4):e13501.
    PMID: 32359088 DOI: 10.1111/dth.13501
    Matched MeSH terms: Renin-Angiotensin System/drug effects*
  7. Draman CR, Kong NC, Gafor AH, Rahman AF, Zainuddin S, Mustaffa WM, et al.
    Singapore Med J, 2008 Nov;49(11):924-9.
    PMID: 19037561
    Angiotensin-converting enzyme (ACE) gene polymorphism, especially the deletion/deletion (DD) genotype, is associated with the disease progression of immunoglobulin A (IgA) nephropathy patients in various studies from both Asia Pacific and European populations. However, recent studies within the same populations were unable to reproduce the same results. Hence, we had studied the distribution of the DD genotype, the association between ACE gene polymorphism and the disease progression, and the factors (other than ACE gene polymorphism) which were involved in the disease progression of our local patients.
    Matched MeSH terms: Renin-Angiotensin System/genetics
  8. Mayurasakorn K, Hasanah N, Homma T, Homma M, Rangel IK, Garza AE, et al.
    Metabolism, 2018 Jun;83:92-101.
    PMID: 29410348 DOI: 10.1016/j.metabol.2018.01.012
    BACKGROUND AND PURPOSE: The plasma membrane protein caveolin-1 (CAV-1) has been shown to be involved in modulating glucose homeostasis and the actions of the renin-angiotensin-aldosterone system (RAAS). Caloric restriction (CR) is widely accepted as an effective therapeutic approach to improve insulin sensitivity and reduce the severity of diabetes. Recent data indicate that polymorphisms of the CAV-1 gene are strongly associated with insulin resistance, hypertension and metabolic abnormalities in non-obese individuals. Therefore, we sought to determine whether CR improves the metabolic and cardiovascular (CV) risk factors in the lean CAV-1 KO mice.

    MATERIALS/METHODS: Twelve- to fourteen-week-old CAV-1 knockout (KO) and genetically matched wild-type (WT) male mice were randomized by genotype to one of two dietary regimens: ad libitum (ad lib) food intake or 40% CR for 4 weeks. Three weeks following the onset of dietary restriction, all groups were assessed for insulin sensitivity. At the end of the study, all groups were assessed for fasting glucose, insulin, HOMA-IR, lipids, corticosterone levels and blood pressure (BP). Aldosterone secretion was determined from acutely isolated Zona Glomerulosa cells.

    RESULTS: We confirmed that the CAV-1 KO mice on the ad lib diet display a phenotype consistent with the cardiometabolic syndrome, as shown by higher systolic BP (SBP), plasma glucose, HOMA-IR and aldosterone levels despite lower body weight compared with WT mice on the ad lib diet. CAV-1 KO mice maintained their body weight on the ad lib diet, but had substantially greater weight loss with CR, as compared to caloric restricted WT mice. CR-mediated changes in weight were associated with dramatic improvements in glucose and insulin tolerance in both genotypes. These responses to CR, however, were more robust in CAV-1KO vs. WT mice and were accompanied by reductions in plasma glucose, insulin and HOMA-IR in CAV-1KO but not WT mice. Surprisingly, in the CAV-1 KO, but not in WT mice, CR was associated with increased SBP and aldosterone levels, suggesting that in CAV-1 KO mice CR induced an increase in some CV risk factors.

    CONCLUSIONS: CR improved the metabolic phenotype in CAV-1 KO mice by increasing insulin sensitivity; nevertheless, this intervention also increased CV risk by inappropriate adaptive responses in the RAAS and BP.

    Matched MeSH terms: Renin-Angiotensin System/physiology
  9. Abdulla MH, Sattar MA, Abdullah NA, Khan MA, Anand Swarup KR, Johns EJ
    Auton Autacoid Pharmacol, 2011 Jan-Apr;31(1-2):13-20.
    PMID: 21166975 DOI: 10.1111/j.1474-8673.2010.00461.x
    1 Interaction between renin-angiotensin (RAS) and sympathetic nervous systems (SNS) was investigated by examining the effect of cumulative blockade of angiotensin II (Ang II) and adrenergic receptors in normal Sprague Dawley rats. 2 Rats were treated with losartan (10 mg/kg), carvedilol (5 mg/kg), or losartan plus carvedilol (10+5 mg/kg) orally for 7 days. On day 8, the animals were anaesthetized with pentobarbitone and prepared for systemic haemodynamic study. Dose-response relationships for the elevation of mean arterial pressure or change in heart rate (HR) in response to intravenous injections of noradrenaline (NA), phenylephrine (PE), methoxamine (ME) and Ang II were determined. 3 Losartan or the combination of losartan with carvedilol blunted vasopressor responses to ME and Ang II. Dose-response relationships for agonist action on HR were significantly inhibited by all treatments except for the combination of losartan and carvedilol on the decrease in HR induced by PE. Carvedilol decreased vasopressor responses to NA, PE and Ang II, and HR responses to NA, ME and Ang II. Combination treatment produced similar effects to losartan on the vasopressor and HR responses but had a greater effect on vasopressor responses to ME and Ang II, and on HR responses to NA and Ang II than carvedilol alone. 4 It is concluded that peripheral vasoconstriction induced by Ang II is partly mediated by adrenergic action and that the vasopressor responses to adrenergic agonists depend on an intact RAS. These observations suggest an interactive relationship between RAS and SNS in determining systemic haemodynamic responses in 'normal' rats.
    Matched MeSH terms: Renin-Angiotensin System/drug effects; Renin-Angiotensin System/physiology
  10. Abdulla MH, Sattar MA, Abdullah NA, Hazim AI, Anand Swarup KR, Rathore HA, et al.
    Auton Autacoid Pharmacol, 2008 Oct;28(4):95-101.
    PMID: 18778332 DOI: 10.1111/j.1474-8673.2008.00422.x
    1. This study was undertaken to elucidate the effects of inhibiting the renin-angiotensin system (RAS) with losartan, and acute unilateral renal denervation on renal haemodynamic responses to intrarenal administration of vasoconstrictor doses of dopamine and vasodilator doses of isoprenaline in Wistar-Kyoto (WKY) and spontaneously hypertensive rats (SHR). 2. Acute unilateral renal denervation of the left kidney in rats was confirmed by a drop in the renal vasoconstrictor response to renal nerve stimulation (P < 0.05) along with diuresis and natriuresis. Rats were pretreated with losartan for 7 days and thereafter animals fasted overnight were anaesthetized (sodium pentobarbitone, 60 mg/kg i.p.) and acute renal haemodynamic responses studied. 3. Dose-response curves were constructed for dopamine and isoprenaline that induced falls or increases in renal blood flow, respectively. It was observed that renal vascular responses were greater in the denervated as compared with rats with intact renal nerves (all P < 0.05). Dopamine-induced renal vasoconstrictor responses were markedly lower in losartan-treated denervated WKY and SHR compared with their untreated counterparts (all P < 0.05). It was also observed that in losartan-treated and denervated WKY rats the vasodilatory responses to isoprenaline were markedly lower compared with untreated rats (all P < 0.05). However, in SHR, under the same conditions, there was no difference in the renal response to isoprenaline whether or not rats were treated with losartan (P > 0.05). 4. The data obtained showed that the renal vasoconstrictor effect of dopamine depends on intact renal nerves and RAS in WKY and SHR. Isoprenaline responses were likewise sensitive to renal denervation and RAS inhibition in WKY rats but not SHRs. Our observations reveal a possible relationship between renal AT(1) receptors and alpha(1)-adrenoceptors in WKY and SHR. There is also evidence to suggest an interaction between renal beta-adrenoceptors and AT(1) receptors in WKY rats.
    Matched MeSH terms: Renin-Angiotensin System/drug effects; Renin-Angiotensin System/physiology*
  11. Ramachandran V, Ismail P, Stanslas J, Shamsudin N
    PMID: 19243623 DOI: 10.1186/1475-2840-8-11
    The renin-angiotensin aldosterone system (RAAS) plays an important role in regulating the blood pressure and the genetic polymorphisms of RAAS genes has been extensively studied in relation to the cardiovascular diseases in various populations with conflicting results. The aim of this study was to determine the association of five genetic polymorphisms (A6G and A20C of angiotensinogen (AGT), MboI of renin, Gly460Trp of aldosterone synthase and Lys173Arg of adducin) of RAAS genes in Malaysian essential hypertensive and type 2 diabetic subjects.
    Matched MeSH terms: Renin-Angiotensin System/genetics*
  12. Heidari F, Vasudevan R, Mohd Ali SZ, Ismail P, Arkani M
    Arch Med Res, 2017 Jan;48(1):88-95.
    PMID: 28577874 DOI: 10.1016/j.arcmed.2017.03.003
    BACKGROUNDS AND AIMS: Essential Hypertension (EH) is a common disorder associated with increased cardiovascular morbidity and mortality in Malaysia. To investigate how genetic polymorphisms of the renin-angiotensin-aldosterone system (RAS) influence EH control with angiotensin-converting enzyme inhibitor drugs (ACEI).

    METHODS: A case-control, cross-sectional population-based nested study (n = 142) included hypertensive subjects treated with ACEI drugs, either lisinopril or enalapril (20 mg, once daily) as monotherapy for 24 weeks. In total seven possible polymorphisms of RAS genes were genotyped. The association between those polymorphisms and the changes in blood pressure were observed in the 24 week treatment.

    RESULTS: Statistically significant associations of I, G, T, M and G alleles of ACE (I/D, G2350A), AGT (M235T, T175M and G-6A) respectively were observed in essential hypertensive subjects. The decrease in systolic blood pressure and diastolic blood pressure after 24 weeks of treatment of the patients carrying II, GG, and TT genotypes were greater than the groups carrying DD, AA, MM, MM and GG of I/D, G2350A, M235T, T174M and G-6A genotypes respectively. In contrast, No significant difference was observed between renin gene polymorphisms (Bg/I and MboI) and hypertensives.

    CONCLUSIONS: Although this study shows a possible association of polymorphisms of RAS genes with the risk of non-control of HT in ACEI-treated patients and indicates the importance of all this system's components in regulating HT, it needs to be replicated in other data sources.

    Matched MeSH terms: Renin-Angiotensin System/genetics*
  13. Azis NA, Agarwal R, Ismail NM, Ismail NH, Kamal MSA, Radjeni Z, et al.
    Mol Biol Rep, 2019 Jun;46(3):2841-2849.
    PMID: 30977084 DOI: 10.1007/s11033-019-04730-w
    This study investigated the effects of a standardised ethanol and water extract of Ficus deltoidea var. Kunstleri (FDK) on blood pressure, renin-angiotensin-aldosterone system (RAAS), endothelial function and antioxidant system in spontaneously hypertensive rats (SHR). Seven groups of male SHR were administered orally in volumes of 0.5 mL of either FDK at doses of 500, 800, 1000 and 1300 mg kg- 1, or captopril at 50 mg kg- 1 or losartan at 10 mg kg- 1 body weight once daily for 4 weeks or 0.5 mL distilled water. Body weight, systolic blood pressures (SBP) and heart rate (HR) were measured every week. 24-hour urine samples were collected at weeks 0 and 4 for electrolyte analysis. At week 4, sera from rats in the control and 1000 mg kg- 1 of FDK treated groups were analyzed for electrolytes and components of RAAS, endothelial function and anti-oxidant capacity. SBP at week 4 was significantly lower in all treatment groups, including captopril and losartan, when compared to that of the controls. Compared to the controls, ACE activity and concentrations of angiotensin I, angiotensin II and aldosterone were lower whereas concentrations of angiotensinogen and angiotensin converting enzyme 2 were higher in FDK treated rats. Concentration of eNOS and total anti-oxidant capacity were higher in FDK treated rats. Urine calcium excretion was higher in FDK treated rats. In conclusion, it appears that ethanol and water extract of FDK decreases blood pressure in SHR, which might involve mechanisms that include RAAS, anti-oxidant and endothelial system.
    Matched MeSH terms: Renin-Angiotensin System/drug effects
  14. Kamal MSA, Ismail NH, Satar NA, Azis NA, Radjeni Z, Mohammad Noor HS, et al.
    Clin Exp Hypertens, 2019;41(5):444-451.
    PMID: 30648895 DOI: 10.1080/10641963.2018.1506467
    Ficus deltoidea is used in Malay traditional medicine for the treatment of a number of disorders, including hypertension. There is, however, no scientific evidence on its anti-hypertensive effects. This study, therefore, investigated the effects of a standardized ethanolic-water extract of Ficus deltoidea Angustifolia (FD-A) on blood pressure (BP) in spontaneously hypertensive rats (SHR). Male SHR with systolic BP of >150 were divided into 4 groups (n = 8) and given either FD-A (800 or 1000 mg kg-1 day-1) or losartan (10 mg kg-1 day-1) or 0.5 ml of distilled water (control) daily for 28 days. BP, body weight, food and water intake, serum and urinary electrolytes, endothelin-1 (ET-1), total antioxidant capacity (TAC) and components of the renin-angiotensin-aldosterone system were measured. Data were analyzed using ANOVA with statistical significance set at p renin-angiotensin-aldosterone system between controls and FD-A treated rats. In conclusion, FD-A when given daily at doses of either 800 or 1000 mg kg-1 day-1 body weight reduces BP in SHR. This effect does not seem to involve the renin-angiotensin-aldosterone-system but might involve some other mechanisms. Abbreviations: FD-A: Ficus deltoidea Angustifolia; ACE: Angiotensin-converting enzyme; SHR: Spontaneously hypertensive rats; SBP: Systolic blood pressure; DBP: Diastolic blood pressure; AUC: Area under curve; RAAS: Renin Angiotensin Aldosterone System.
    Matched MeSH terms: Renin-Angiotensin System/drug effects
  15. Tee BH, Hoe SZ, Cheah SH, Lam SK
    Biomed Res Int, 2016;2016:1361508.
    PMID: 27800486 DOI: 10.1155/2016/1361508
    Although Eurycoma longifolia has been studied for erectile function, the blood pressure- (BP-) lowering effect has yet to be verified. Hence, this study aims at investigating the BP-lowering properties of the plant with a view to develop an antihypertensive agent that could also preserve erectile function. Ethanolic root extract was partitioned by hexane, dichloromethane (DCM), ethyl acetate, butanol, and water. The DCM fraction, found to be potent in relaxing phenylephrine- (PE-) precontracted rat aortic rings, was further purified by column chromatography. Subfraction DCM-II, being the most active in relaxing aortae, was studied for effects on the renin-angiotensin and kallikrein-kinin systems in aortic rings. The effect of DCM-II on angiotensin-converting enzyme (ACE) activity was also evaluated in vitro. Results showed that DCM-II reduced (p < 0.05) the contractions evoked by angiotensin I and angiotensin II (Ang II). In PE-precontracted rings treated with DCM-II, the Ang II-induced contraction was attenuated (p < 0.05) while bradykinin- (BK-) induced relaxation enhanced (p < 0.001). In vitro, DCM-II inhibited (p < 0.001) the activity of ACE. These data demonstrate that the vasodilatory effect of DCM-II appears to be mediated via inhibition of Ang II type 1 receptor and ACE as well as enhancement of Ang II type 2 receptor activation and BK activity.
    Matched MeSH terms: Renin-Angiotensin System/drug effects
  16. Ng YP, Balasubramanian GP, Heng YP, Kalaiselvan M, Teh YW, Cheong KM, et al.
    Diabetes Metab Syndr, 2018 May;12(3):305-308.
    PMID: 29279269 DOI: 10.1016/j.dsx.2017.12.005
    AIMS: Recent data showed an alarming rise of new dialysis cases secondary to diabetic nephropathy despite the growing usage of RAAS blockers. Primary objective of this study is to explore the prevalence of RAAS blockers usage among type II diabetic patients, secondary objectives are to compare the prescribing pattern of RAAS blocker between primary and tertiary care center and to explore if the dose of RAAS blocker prescribed was at optimal dose as suggested by trials.

    MATERIALS AND METHODS: This is a retrospective study conducted at one public tertiary referral hospital and one public health clinic in Sungai Petani, Kedah, Malaysia.

    RESULTS: RAAS blockers in T2DM patients was found to be 65%. In primary care, 14.3% of the RAAS blockers prescribed was ARB. Tertiary care had higher utilization of ARB, which was 42.9%. In primary care setting, the most commonly used ACEI were perindopril (92.4%) followed by enalapril (7.6%), meanwhile perindopril was the only ACEI being prescribed in tertiary care. The most prescribed ARB was irbesartan (63.6%) and telmisartan (54.2%) respectively in primary and tertiary care. Overall, 64.9% of RAAS blockers prescribed by both levels of care were found to be achieving the target dose as recommended in landmark trials. Crude odd ratio of prescribing RAAS blocker in primary care versus tertiary care was reported as 2.70 (95% CI: 1.49 to 4.91).

    CONCLUSION: RAAS blockers usage among T2DM patients was higher in primary care versus tertiary care settings. Majority of the patients did not receive optimal dose of RAAS blockers.
    Matched MeSH terms: Renin-Angiotensin System/drug effects*
  17. Manoharan S, Shuib AS, Abdullah N
    PMID: 28573254 DOI: 10.21010/ajtcam.v14i2.39
    BACKGROUND: The commercially available synthetic angiotensin-I-converting enzyme (ACE) inhibitors are known to exert negative side effects which have driven many research groups globally to discover the novel ACE inhibitors.

    METHOD: Literature search was performed within the PubMed, ScienceDirect.com and Google Scholar.

    RESULTS: The presence of proline at the C-terminal tripeptide of ACE inhibitor can competitively inhibit the ACE activity. The effects of other amino acids are less studied leading to difficulties in predicting potent peptide sequences. The broad specificity of the enzyme may be due to the dual active sites observed on the somatic ACE. The inhibitors may not necessarily competitively inhibit the enzyme which explains why some reported inhibitors do not have the common ACE inhibitor characteristics. Finally, the in vivo assay has to be carried out before the peptides as the antihypertensive agents can be claimed. The peptides must be absorbed into circulation without being degraded, which will affect their bioavailability and potency. Thus, peptides with strong in vitro IC50 values do not necessarily have the same effect in vivo and vice versa.

    CONCLUSION: The relationship between peptide amino acid sequence and inhibitory activity, in vivo studies of the active peptides and bioavailability must be studied before the peptides as antihypertensive agents can be claimed.

    Matched MeSH terms: Renin-Angiotensin System/drug effects*
  18. Kow CS, Zaidi STR, Hasan SS
    Am J Cardiovasc Drugs, 2020 Jun;20(3):217-221.
    PMID: 32281055 DOI: 10.1007/s40256-020-00406-0
    There is ongoing debate on the safety of renin-angiotensin system (RAS) inhibitors in COVID-19. Recently published studies highlight a potential relationship between cardiovascular disease (CVD) and COVID-19. This article aims to summarize the evidence on the use of RAS inhibitors in CVD patients with COVID-19, focusing on safety issues of the RAS inhibitors and their relationship with COVID-19.
    Matched MeSH terms: Renin-Angiotensin System/drug effects*
  19. Smith PM, Hindmarch CC, Murphy D, Ferguson AV
    Front Psychol, 2014;5:832.
    PMID: 25120524 DOI: 10.3389/fpsyg.2014.00832
    Obesity is a chronic metabolic condition with important public health implications associated with numerous co-morbidities including cardiovascular disease, insulin resistance, and hypertension. The renin angiotensin system (RAS), best known for its involvement in cardiovascular control and body fluid homeostasis has, more recently, been implicated in regulation of energy balance. Interference with the RAS (genetically or pharmacologically) has been shown to influence body weight gain. In this study we investigated the effects of systemic AT1 receptor blockade using losartan on ingestive behaviors and weight gain in diet induced obese (DIO) rats. Prior to losartan administration (30 mg/kg/day) body weight gain remained constant within the DIO animals (3.6 ± 0.3 g/day, n = 8), diet resistant (DR) animals (2.1 ± 0.6 g/day, n = 8) and in the age-matched chow fed control (CHOW) animals (2.8 ± 0.3 g/day, n = 8), Losartan administration abolished body weight gain in animals fed a high fat diet (DIO: -0.4 ± 0.7 g/day, n = 8; and DR: -0.8 ± 0.3 g/day, n = 8) while chow fed animals continued to gain weight (2.2 ± 0.3 g/day, n = 8) as they had previously to oral administration of losartan. This decrease in daily body weight gain was accompanied by a decrease in food intake in the HFD fed animals. Following the removal of losartan, both the DIO and DR animals again showed daily increases in body weight gain and food intake which were similar to control values. Our data demonstrate that oral losartan administration attenuates body weight gain in animals fed a HFD whether the animal is obese (DIO) or not DR while having no effect on body weight gain in age-matched chow fed animals suggesting a protective effect of losartan against body weight gain while on a HFD.
    Matched MeSH terms: Renin-Angiotensin System
  20. Gan R, Rosoman NP, Henshaw DJE, Noble EP, Georgius P, Sommerfeld N
    Med Hypotheses, 2020 Nov;144:110024.
    PMID: 32758871 DOI: 10.1016/j.mehy.2020.110024
    SARS-CoV-2, the agent of COVID-19, shares a lineage with SARS-CoV-1, and a common fatal pulmonary profile but with striking differences in presentation, clinical course, and response to treatment. In contrast to SARS-CoV-1 (SARS), COVID-19 has presented as an often bi-phasic, multi-organ pathology, with a proclivity for severe disease in the elderly and those with hypertension, diabetes and cardiovascular disease. Whilst death is usually related to respiratory collapse, autopsy reveals multi-organ pathology. Chronic pulmonary disease is underrepresented in the group with severe COVID-19. A commonality of aberrant renin angiotensin system (RAS) is suggested in the at-risk group. The identification of angiotensin-converting-enzyme 2 (ACE2) as the receptor allowing viral entry to cells precipitated our interest in the role of ACE2 in COVID-19 pathogenesis. We propose that COVID-19 is a viral multisystem disease, with dominant vascular pathology, mediated by global reduction in ACE2 function, pronounced in disease conditions with RAS bias toward angiotensin-converting-enzyme (ACE) over ACE2. It is further complicated by organ specific pathology related to loss of ACE2 expressing cells particularly affecting the endothelium, alveolus, glomerulus and cardiac microvasculature. The possible upregulation in ACE2 receptor expression may predispose individuals with aberrant RAS status to higher viral load on infection and relatively more cell loss. Relative ACE2 deficiency leads to enhanced and protracted tissue, and vessel exposure to angiotensin II, characterised by vasoconstriction, enhanced thrombosis, cell proliferation and recruitment, increased tissue permeability, and cytokine production (including IL-6) resulting in inflammation. Additionally, there is a profound loss of the "protective" angiotensin (1-7), a vasodilator with anti-inflammatory, anti-thrombotic, antiproliferative, antifibrotic, anti-arrhythmic, and antioxidant activity. Our model predicts global vascular insult related to direct endothelial cell damage, vasoconstriction and thrombosis with a disease specific cytokine profile related to angiotensin II rather than "cytokine storm". Our proposed mechanism of lung injury provides an explanation for early hypoxia without reduction in lung compliance and suggests a need for revision of treatment protocols to address vasoconstriction, thromboprophylaxis, and to minimize additional small airways and alveolar trauma via ventilation choice. Our model predicts long term sequelae of scarring/fibrosis in vessels, lungs, renal and cardiac tissue with protracted illness in at-risk individuals. It is hoped that our model stimulates review of current diagnostic and therapeutic intervention protocols, particularly with respect to early anticoagulation, vasodilatation and revision of ventilatory support choices.
    Matched MeSH terms: Renin-Angiotensin System
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