Plasma ACE Activity Research Articles

ER stress improvement by aerobic training or enalapril differently ameliorates pathological cardiac remodeling in obese mice.

Overactivation of the classic arm of the renin-angiotensin system (RAS) is one of the main mechanisms involved in obesity-related cardiac remodeling, and a possible relationship between RAS and ER stress in the cardiovascular system have been described. Thus, the aim of this study is to evaluate if activating the protective arm of the RAS by ACE inhibition or aerobic exercise training could overturn diet-induced pathological cardiac hypertrophy by attenuating ER stress. Male C57BL/6 mice were fed a control (SC) or a high-fat diet (HF) for 16weeks. In the 8th week, HF-fed animals were randomly divided into HF, enalapril treatment (HF-En), and aerobic exercise training (HF-Ex) groups. Body mass (BM), food and energy intake, plasma analyzes, systolic blood pressure (SBP), physical conditioning, and plasma ACE and ACE2 activity were evaluated. Cardiac morphology, and protein expression of hypertrophy, cardiac metabolism, RAS, and ER stress markers were assessed. Data presented as mean ± standard deviation and analyzed by one-way ANOVA with Holm-Sidak post-hoc. HF group had increased BM and SBP, and developed pathological concentric cardiac hypertrophy, with overactivation of the classic arm of the RAS, and higher ER stress. Both interventions reverted the increase in BM, and SBP, and favored the protective arm of the RAS. Enalapril treatment improved pathological cardiac hypertrophy with partial reversal of the concentric pattern, and slightly attenuated cardiac ER stress. In contrast, aerobic exercise training induced physiological eccentric cardiac hypertrophy, and fully diminished ER stress.

In vitro and in vivo antihypertensive and antioxidant activities of fermented roots of Allium hookeri

ObjectiveTo evaluate antihypertensive and antioxidant activities of Allium hookeri root (AHR) fermented with Lactobacillus plantarum, Leuconostoc mesenteroides, and Weissella cibaria. MethodsThe novel fermented AHR products using L. plantarum, L. mesenteroides, and W. cibaria were developed and ACE inhibitory activity, DPPH radical scavenging activity, hydroxyl radical scavenging activity, superoxide anion radical scavenging activity, total phenolic content, and total thiosulfinate content were determined. The antihypertensive and antioxidant effects of fermented AHR were further investigated in spontaneously hypertensive rats (SHRs). ResultsAdministration of fermented AHR to SHRs had an attenuating effect on both diastolic and systolic blood pressure. The SHRs treated with fermented AHR showed lower plasma ACE activity and higher plasma NO levels. Furthermore, fermented AHR administration led to parallel improvements in plasma oxidative stress biomarkers in SHRs. ConclusionOur results highlight the potential usefulness of fermented AHR for the prevention of hypertension.

Effect of Angiotensin‐converting Enzyme Inhibition on Systemic and Renal RAS Components in a Hyperandrogenemic Rat Model of PCOS

Polycystic Ovary Syndrome (PCOS) is characterized by androgen excess, oligo/anovulation, and polycystic ovaries. Obesity, insulin resistance (IR) and increased blood pressure (BP) are associated with PCOS. Therapeutic options for PCOS are limited and the mechanisms responsible for the cardiometabolic complications seen in PCOS are uncertain. It is unclear if androgen-mediated increases in BP contribute to obesity and/or IR in PCOS. The renin angiotensin system (RAS), a regulator of BP, is affected by androgens and is associated with increased BP in PCOS. To investigate the role of androgens and the contribution of the RAS in PCOS, RAS inhibition via an angiotensin-converting enzyme inhibitor (ACEi) was performed in a PCOS-like rat model. We hypothesized that ACEi would attenuate obesity and IR in PCOS. Female SD rats (4 week old) received dihydrotestosterone (DHT, 7.5 mg/ 90 days) pellets (HAF) subcutaneously or sham surgeries (CON). The rats were then assigned tap water or tap water with the ACEi, enalapril (ENA) (250mg/L) for n=10/group. At the end of the study (16 week old) body weight (BW), body composition by EchoMRI, and IR by HOMA-IR were assessed. Renal RAS gene expression was assessed by qPCR. BP was measured by radiotelemetry and plasma and renal ACE and ACE2 activities were assessed. HAF had increased BW, fat mass and IR vs CON. ENA reduced BW in only HAF. Overall, ENA decreased fat mass, and the decrease in HAF neared significance. ENA did not attenuate IR in HAF. In HAF, angiotensinogen (Agt) mRNA was increased in the renal cortex and medulla, while ACE and angiotensin II receptor type 1a (Atr1a) mRNA was increased in the medulla vs CON. In HAF, ENA had no impact on renal Agt, ACE or Atr1a mRNA. ACE2 mRNA was increased in the medulla of HAF vs CON, and ENA increased medulla ACE2 mRNA in both HAF and CON. HAF had increased BP, and ENA decreased BP in both HAF and CON by a similar degree. Overall, ENA decreased plasma ACE activity but only increased plasma ACE2 activity in HAF. ENA increased cortical ACE2 activity in both HAF and CON. In summary, ACEi therapy in a PCOS model reduced BW, BP and adiposity but had no impact on IR. Renal classic RAS gene expression is upregulated in the HAF but unchanged by ENA. Furthermore, only ACE2 mRNA expression was altered in the HAF with ENA. In addition, the expression of other RAS component genes that were unchanged by ACEi in HAF were significantly impacted by ACEi in CON. This reveals a complex interaction between androgen exposure and renal RAS component gene expression. Increased BP in the HAF did not correlate with plasma or renal ACE or ACE2 activities. Chronic RAS inhibition may be a promising therapeutic approach for androgen-mediated increases in BP and obesity in AE-PCOS, though additional therapy would be needed for IR.

The role of insertion-deletion polymorphism of the ACE gene in development of arterial hypertension in patients with chronic obstructive pulmonary disease

Objective. This study aims to establish the role of insertion-deletion polymorphism of the angiotensin-converting enzyme gene in development of arterial hypertension in patients with chronic obstructive pulmonary disease.
 Materials and Methods: The study group consisted of 96 patients: Group 1 (25 individuals with COPD), Group 2 (23 individuals with AH), Group 3 (28 individuals with COPD and AH). The control group consisted of the 20 healthy subjects. I/D genotypes of ACE were determined by polymerase chain reaction (PCR) amplification. Plasma ACE activity was determined photometrically by a commercially available kit.
 Results and Discussion: The distribution of polymorphic variants of the ACE gene among COPD-only patients genotype spreading was close to the data obtained in controls. In hypertensive patients, there were fewer ID heterozygotes and more ІІ homozygotes compared to controls. In the COPD+AH category of patients, II genotype was predominant in 7.1% subjects, DD genotype was predominant in 10.0% subjects and the proportion of ID heterozygotes was 17.1% lower compared to controls. The II genotype had a positive relationship with patient age and a negative relationship with body weights and respiratory rates of COPD+AH patients. The ID genotype was associated with increased respiratory rates; however, its correlation with the duration of the disease was negative.
 Conclusion: The data obtained in the study allow suggesting that polymorphism of the ACE gene doesn’t relate to development of AH in patients with COPD. The highest activity of ACE was found in patients with combination of COPD and AH; maximum findings of ACE activity were seen in patients with DD genotype.
 Bangladesh Journal of Medical Science Vol.19(3) 2020 p.543-551

Evidence that Nitric Oxide is Involved in the Blood Pressure Lowering Effect of the Peptide AVFQHNCQE in Spontaneously Hypertensive Rats.

AVFQHNCQE is an antihypertensive nonapeptide obtained from a chicken foot protein hydrolysate. The present study aims to investigate the mechanisms involved in its blood pressure (BP)-lowering effect. Male (17–20 weeks old) spontaneously hypertensive rats (SHR) were used in this study. Rats were divided into two groups and orally administered water or 10 mg/kg body weight (bw) AVFQHNCQE. One hour post-administration, animals of both groups were intra-peritoneally treated with 1 mL of saline or with 1 mL of saline containing 30 mg/kg bw Nω-nitro-L-arginine methyl ester (L-NAME), an inhibitor of nitric oxide (NO) synthesis, or with 1 mL of saline containing 5 mg/kg bw indomethacin, which is an inhibitor of prostacyclin synthesis (n = 6 per group). Systolic BP was recorded before oral administration and six hours after oral administration. In an additional experiment, SHR were administered water or 10 mg/kg bw AVFQHNCQE (n = 6 per group) and sacrificed six hours post-administration to study the mechanisms underlying the peptide anti-hypertensive effect. Moreover, the relaxation caused by AVFQHNCQE in isolated aortic rings from Sprague-Dawley rats was evaluated. The BP-lowering effect of the peptide was not changed after indomethacin administration but was completely abolished by L-NAME, which demonstrates that its anti-hypertensive effect is mediated by changes in endothelium-derived NO availability. In addition, AVFQHNCQE administration downregulated aortic gene expression of the vasoconstrictor factor endothelin-1 and the endothelial major free radical producer NADPH. Moreover, while no changes in plasma ACE activity were observed after its administration, liver GSH levels were higher in the peptide-treated group than in the water group, which demonstrates that AVFQHNCQE presents antioxidant properties.

Renin angiotensin system and pulmonary hemodynamics in chronic obstructive pulmonary disease

Background: Pulmonary hypertension in chronic obstructive pulmonary disease (COPD) due to chronic alveolar hypoxia is probably the main contributor to the pathogenesis of pulmonary hypertension in COPD. Angiotensin II is a potent vasoconstrictor in renin angiotensin aldosterone system (RAAS), it has been shown to promote growth response in vascular smooth muscle cell contributing towards pulmonary hypertension. So, the Echocardiographicaliy measured MPAP and its correlation with RAAS in patients of COPD was evaluated.Methods: A prospective observational study was done in 32 patients with COPD and 10 age matched healthy, non-smoker subject included as controls. Stable patients requiring no change in their medication in the previous four weeks and not having had an acute exacerbation in that period were included. MPAP was calculated. Measurement of Ang II and aldosterone was done.Results: Thirty-two cases of COPD, meeting inclusion criteria were enrolled comprising of 32 males and the mean age of patients ±2sd was (55.6 ±16.8), while mean age of controls ± 2sd was 49.60 ±5.56. Arterial blood gas analysis, PaO2 was ranged from (mean±2sd 75.44±12.1), PaCo2 ranged from (mean ±2sd 41.36±3.79) and SpO2 ranged from (mean±2sd 94.03 2±.74). Mean ±2sd of plasma Ang II in COPD cases was (4.9±3.8) ng/dl, significantly higher in comparison with controls (p < 0.001). Mean ±2sd of plasma ACE activity was (51.12±26.9) in COPD. Mean ±2sd of plasma aldosterone was (182.35±364.2) in COPD cases with significant (p<0.01). The MPAP in COPD cases was (mean±2sd 34.53±7.70).Conclusions: Use of Doppler has the advantage of being noninvasive and has been shown to be extremely reproducible in evaluation of MPAP and CO. The increased level of Ang II with increase MPAP in the present study would suggest that this may be a suitable model for investigating effects of novel vasodilator drugs for the treatment of pulmonary hypertension developed due to COPD.

Decreased potency of fimasartan in liver cirrhosis was quantified using mixed-effects analysis.

Fimasartan is a nonpeptide angiotensin II receptor blocker. In a previous study that compared the pharmacokinetics (PK) of fimasartan between patients with hepatic impairment (cirrhosis) and healthy subjects, the exposure to fimasartan was found to be higher in patients, but the decrease of blood pressure (BP) was not clinically significant in those with moderate hepatic impairment. The aims of this study were to develop a population PK-pharmacodynamic (PD) model of fimasartan and to evaluate the effect of hepatic function on BP reduction by fimasartan using previously published data. A 2-compartment linear model with mixed zero-order absorption followed by first-order absorption with a lag time adequately described fimasartan PK, and the effect of fimasartan on BP changes was well explained by the inhibitory sigmoid function in the turnover PK-PD model overlaid with a model of circadian rhythm (NONMEM version 7.2). According to our PD model, the lower BP responses in hepatic impairment were the result of the increased fimasartan EC50 in patients, rather than from a saturation of effect. This is congruent with the reported pathophysiological change of increased plasma ACE and renin activity in hepatic cirrhosis.

Renin-angiotensin system gene polymorphisms and endometrial cancer.

Endometrial cancer (EC) is the most common gynaecological malignancy and its incidence is increasing. Dysregulation of the endometrial renin–angiotensin system (RAS) could predispose to EC; therefore, we studied the prevalence of RAS single nucleotide polymorphisms (SNPs) in Australian women with EC. SNPs assessed were AGT M235T (rs699); AGTR1 A1166C (rs5186); ACE A240T and T93C (rs4291, rs4292) and ATP6AP2 (rs2968915). They were identified using TaqMan SNP Genotyping Assays. The C allele of the AGTR1 SNP (rs5186) was more prevalent in women with EC (odds ratio (OR) 1.7, 95% confidence interval (CI) (1.2–2.3), P=0.002). The CC genotype of this SNP is associated with upregulation of the angiotensin II type 1 receptor (AGTR1). The G allele of AGT rs699, which is associated with higher angiotensinogen (AGT) levels, was less prevalent in women with EC (OR 0.54, 95% CI (0.39–0.74), P<0.001) compared with controls. AGT and AGT formed by removal of angiotensin I (des(Ang I)AGT) are both anti-angiogenic. In women with EC who had had hormone replacement therapy (HRT), the prevalence of the AGTR1 SNP (rs5186) and the ACE SNPs (rs4291 and rs4292) was greater than in women who had no record of HRT; SNP rs4291 is associated with increased plasma ACE activity. These data suggest there is an interaction between genotype, oestrogen replacement therapy and EC. In conclusion, the prevalence of two SNPs that enhance RAS activity was different in women with EC compared with healthy controls. These genetic factors may interact with obesity and hyperoestrogenism, predisposing ageing, obese women to EC.

Antihypertensive and cardioprotective effects of the dipeptide isoleucine-tryptophan and whey protein hydrolysate.

Angiotensin-converting enzyme inhibitors are treatment of choice in hypertensive patients. Clinically used inhibitors exhibit a structural similarity to naturally occurring peptides. This study evaluated antihypertensive and cardioprotective effects of ACE-inhibiting peptides derived from food proteins in spontaneously hypertensive rats. Isoleucine-tryptophan (in vitro IC50 for ACE = 0.7 μm), a whey protein hydrolysate containing an augmented fraction of isoleucine-tryptophan, or captopril was given to spontaneously hypertensive rats (n = 60) over 14 weeks. Two further groups, receiving either no supplement (Placebo) or intact whey protein, served as controls. Systolic blood pressure age-dependently increased in the Placebo group, whereas the blood pressure rise was effectively blunted by isoleucine-tryptophan, whey protein hydrolysate and captopril (-42 ± 3, -38 ± 5, -55 ± 4 mm Hg vs. Placebo). At study end, myocardial mass was lower in isoleucine-tryptophan and captopril groups but only partially in the hydrolysate group. Coronary flow reserve (1 μm adenosine) was improved in isoleucine-tryptophan and captopril groups. Plasma ACE activity was significantly decreased in isoleucine-tryptophan, hydrolysate and captopril groups, but in aortic tissue only after isoleucine-tryptophan or captopril treatment. This was associated with lowered expression and activity of matrix metalloproteinase-2. Following isoleucine-tryptophan and captopril treatments, gene expression of renin was significantly increased indicating an active feedback within renin-angiotensin system. Whey protein hydrolysate and isoleucine-tryptophan powerfully inhibit plasma ACE resulting in antihypertensive effects. Moreover, isoleucine-tryptophan blunts tissue ACE activity, reduces matrix metalloproteinase-2 activity and improves coronary flow reserve. Thus, whey protein hydrolysate and particularly isoleucine-tryptophan may serve as innovative food additives with the goal of attenuating hypertension.

Characterization of placental and fetal development in an animal model of severe arterial hypertension

Effects of kidney transplantation on the renin-angiotensin systems of the recipients. To investigate the effects of renal transplantation on the plasma and local kidney renin-angiotensin systems of the recipients the left kidneys of 13 adult male Wistar-Kyoto rats (WKY) and 13 stroke-prone spontaneously hypertensive rats (SHRSP) were transplanted to bilaterally nephrectomized (WKYxSHRSP)-F1 hybrids. Nine unilaterally nephrectomized WKY and nine SHRSP served as controls. Four weeks after surgery recipients of an SHRSP kidney but not recipients of a WKY kidney had significant post-transplantation hypertension. Plasma renin activity (PRA) was higher in SHRSP than in WKY. Transplanted rats had lower PRAs than nontransplanted controls. Plasma ACE activity was lowest in SHRSP, intermediate in transplanted F1 hybrids and highest in WKY. Plasma Ang I and Ang II concentrations closely paralleled each other. They were not significantly different between WKY and SHRSP and lower in transplanted than in nontransplanted rats. ACE and renin mRNA were lower in transplanted than in nontransplanted kidneys. Glomerular angiotensin II receptor density was higher in transplanted than in nontransplanted kidneys with no significant differences between strains. We conclude that renal transplantation has profound long-term effects on the recipients' plasma and local kidney renin-angiotensin systems. These do not appear to be involved in the pathogenesis of post-transplantation hypertension in recipients of an SHRSP kidney, but may reflect a role for the intrarenal renin-angiotensin system in long-term renal adaptation and repair processes after transplantation.

The effect of enalapril on furosemide-activated renin-angiotensin-aldosterone system in healthy dogs.

Studies in our laboratory have revealed that furosemide-induced RAAS activation, evaluated via the urine aldosterone-to-creatinine ratio (UAldo:C), was not attenuated by the coadministration of benazepril, while enalapril successfully suppressed amlodipine-induced urinary aldosterone excretion. This study was designed to evaluate the efficacy of enalapril in suppressing ACE activity and furosemide-induced circulating RAAS activation. Failure to do so would suggest that this failure may be a drug class effect. We hypothesized that enalapril would suppress ACE activity and furosemide-induced circulating RAAS activation. Sixteen healthy hound dogs. The effect of furosemide (2 mg/kg PO, q12 h; Group F) and furosemide plus enalapril (0.5 mg/kg PO, q12 h; Group FE) on circulating RAAS was determined by plasma ACE activity, 4-6 h post-treatment, and urinary A:C on days -1, -2, 1, 4, and 7. There was a significant increase in the average urine aldosterone-to-creatinine ratio (UAldo:C) after administration of furosemide (P < 0.05). Enalapril inhibited ACE activity (P < 0.0001) but did not significantly reduce aldosterone excretion. A significant (P < 0.05) increase in the UAldo:C was maintained for the 7 days of the study in both groups. Enalapril decreased plasma ACE activity; however, it did not suppress furosemide-induced RAAS activation, as determined by the UAldo:C. While enalapril blunts ACE activity, the absence of circulating RAAS suppression may be due to angiotensin II reactivation, alternative RAAS pathways, and furosemide overriding concurrent ACE inhibition, all indicating the existence of aldosterone breakthrough (ABT). Along with similar findings with benazepril, it appears that failure to suppress aldosterone suppression with furosemide stimulation may be a drug class effect. The discrepancy between the current data and the documented benefits of enalapril likely reflects the efficacy of this ACE inhibitor in suppressing tissue RAAS, variable population responsiveness to ACE-inhibition, and/or providing additional survival benefits, possibly through as yet unknown mechanisms.

Early developmental exposure to high fructose intake in rats with NaCl stimulation causes cardiac damage.

Metabolic syndrome (MS) increases the risk of type 2 diabetes and cardiovascular disease. High consumption of fructose is a proposed cause of increased MS, manifested through hypertension, obesity, insulin resistance, and dyslipidemia. High NaCl also increases the risk of CD. The purpose of this study is to evaluate the influence of fructose and sodium on autonomic dysfunction and its relation with CD in MS. Fructose overload was started at weaning and continued through adulthood. Male Wistar rats (21 days) were divided into four groups: Control (C), fructose consumption (10%, F), NaCl consumption (salt 1% for the 10 last days, S), and fructose and NaCl (FS), and monitored for 8 weeks. Metabolic evaluations consisted of Lee index, glycemia, insulin and glucose tolerance tests, triglycerides, and total cholesterol measurements. Cardiovascular parameters measured were arterial pressure (AP) and cardiac function performed by echocardiography. They also measured the influence of renin angiotensin (RAS) and autonomic nervous systems by drug blockage with losartan, atropine, and atenolol. Energy analysis showed no change between groups. Fructose overload induced a MS state, confirmed by insulin resistance, glucose intolerance, and dyslipidemia. Fasting glucose was increased in F and FS rat groups compared with C and S groups. AP was higher in F, S, and FS groups in comparison with the C group. The hypotensive response after sympathetic blockade was increased in F, S, and FS versus C. The cardiac vagal tonus was reduced in F and FS animal groups. The intrinsic heart rate was decreased in the FS group (372 ± 9 bpm) compared with the C group (410 ± 13 bpm). The morphometric measurements evaluated through left ventricular diameter during diastole and the left ventricular diameter during systole decreased in the FS group (16 and 26%, respectively). Diastolic function was reduced in F and FS. The depressor response induced by losartan was increased in the F group in comparison with other groups. However, there was a uniform increase in plasma ACE activity in all treated groups compared with the C group. Data suggest that early exposure to high fructose intake produced marked alterations in metabolic and cardiovascular function. When stimulated by NaCl, the fructose-fed subjects showed further impairment in cardiac function.

GW24-e1391 Angiotensin-(1-7) inhibits vascular calcification in rats

ObjectivesAngiotensin-(1-7) [Ang-(1-7)] is a new bioactive heptapeptide in the renin-angiotensin system (RAS). It is produced mainly by the activity of angiotensin-converting enzyme 2 (ACE2) and acts through the Mas receptor....

Low-molecular procyanidin rich grape seed extract exerts antihypertensive effect in males spontaneously hypertensive rats

Grapes are a good source of flavonoids, which have been previously demonstrated to exert beneficial healthy effects on cardiovascular diseases. The aims of this study were to extensively characterise a grape seed procyanidin extract (GSPE) (total phenolic content, antioxidant capacity and HPLC–MS phenolic profile) and, to assess its antihypertensive effect in spontaneously hypertensive rats (SHR) which is a model of genetically hypertensive rat analogue to the essential hypertension in humans. The hypotensive effect of GSPE was also proved in normotensive Wistar–Kyoto rats. Chromatographic analysis of the extract showed that the most abundant polyphenols are monomers and dimers, in their free forms and linked to a gallate. GSPE produced a significant decrease in systolic and diastolic blood pressure of SHR dose-dependently up to 375mg/kg (maximum decrease 6h post-administration) and did not affect blood pressure of Wistar–Kyoto rats. GSPE increased the activity of an antioxidant endogen system, but did not affect plasma ACE activity in these animals.

Effect of Telmisartan on the Regression of the Left Ventricular Hypertrophy in the Patients of Essential Hypertension

An increase in the Left Ventricular Mass as a result of muscle hypertrophy, has emerged as a powerful pressure independent risk factor for the cardiovascular mortality and morbidity. It is associated with a risk of death that is 3 times greater than the risk which is associated with hypertension alone. For the development of Left Ventricular Hypertrophy (LVH), in addition to a chronic increase in the pressure and/or volume overload, an elevation in the plasma ACE activity, plasma aldosterone levels, and the angiotensin-II concentrations play a major role .In this study, the effect of Telmisartan, a selective angiotension-II receptor blocker, was compared with that of Atenolol, a selective β1adrenergic receptor blocker, on the regression of LVH in the patients of essential hypertension. Essential hypertensive patients with LVH were selected for this study, as per the inclusion and exclusion criteria. This study was carried out on two groups of hypertensive patients with LVH: Group-1: The patients who were taking telmisartan 80 mg OD. Group-2: The patients who were taking atenolol 50 mg OD. The blood pressure was measured and echocardiography was done in both the groups, prior to the treatment and 6 months after the treatment in the Department of Cardiology, MKCG Medical College Hospital, Brahmapur, India. The data were analysed by using the Student's 't' test. In the cases of Left Ventricular Mass Index (LVMI), which is a better indicator of LVH, in the Atenolol group, the mean value changed from 143.93 ± 2.44 gm/m(2) to 130.16 ± 2.88 gm/m(2) (t=5.83,p<0.01versus baseline).In the Telmisartan group, the mean value changed from 184.67 ± 7.14 gm/m(2) to 133.41± 4.24 gm/m(2) (t=12.12, p<0.001versus baseline). On comparing Telmisartan with Atenolol, Telmisartan was found to produce a greater (27.49%) reduction than Atenolol (9.68%). In the Telmisartan group, 13 patients out of 26 patients achieved a target value of LVMI that was <134 gm/m(2) in males and <110 gm/m(2) in females (50%). In the Atenolol group, only 9 patients out of 22patients achieved a target value (40.90%). Thus, Telmisartan a selective AT1antagonist, possesses pharmacological effects beyond a blood pressure reduction in which the blockade of the AT1receptor may lead to attenuation of the growth promoting action of Ang II. From this study, it is clear that Telmisartan is superior to Atenolol in achieving a regression of LVH, which is a better indicator of the cardiovascular morbidity and mortality.

Comprehensive Evaluation of the Effects of Enalapril on Matrix Metalloproteinases Levels in Hypertension

Angiotensin-converting enzyme inhibitors (ACEi) may downregulate matrix metalloproteinases (MMPs). We examined whether enalapril affects MMP-2, MMP-8, and MMP-9 levels and activity, and their endogenous inhibitors (tissue inhibitors of MMPs, TIMP-1 and TIMP-2) levels in hypertensive patients. Moreover, we assessed the effects of enalaprilat on MMP-9 and TIMP-1 secretion by human endothelial cells (HUVECs). Thirty-eight hypertensive patients received enalapril for 8 weeks and were compared with thirty-eight normotensive controls. Blood samples were collected at baseline and after treatment. Plasma ACE activity was determined by a fluorimetric assay. Plasma MMP-2, MMP-8, MMP-9, TIMP-1, and TIMP-2 were measured by ELISA and gelatin zymography. A fluorogenic peptide cleavage assay was used to measure MMP activity. HUVECs cells were stimulated by phorbol-12-myristate-13-acetate (PMA) and the effects of enalaprilat (10(-10) to 10(-6) M) on MMP-9 and TIMP-1 levels were determined. Enalapril decreased blood pressure and ACE activity in hypertensive patients (P < 0.05), but had no effects on plasma MMP-2, MMP-8, MMP-9, TIMP-1, and TIMP-2 levels, or MMP activity. Enalaprilat had no effects on PMA-induced increases in MMP-9 and TIMP-1 secretion by HUVECs or on MMP activity. We show consistent evidence, both in vivo and in vitro, that enalapril does not affect MMPs and TIMPs levels in hypertensive patients.

Decreased aortal angiotensin converting enzyme 2 (ACE2) and phospho‐eNOS protein expression in db/db diabetic mice

Cardiovascular disease is a long term complication of diabetes and remains a leading cause of morbidity and mortality. ACE2 is a homologue of ACE that preferentially converts the vasopressor angiotensin II (Ang II) to the vasodilator Ang (1–7). Endothelial nitric oxide synthase (eNOS) produces the endogenous vasodilator nitric oxide (NO). There is evidence that diabetes impairs ACE2 and NO-mediated vasodilation. Our previous studies demonstrated an age-dependent increase of blood pressure in db/db type 2 diabetic mice. The goal of this study was to investigate the role ACE2 and phospho-eNOS in the pathogenesis of hypertension in db/db diabetic mice. Plasma and tissue ACE and ACE2 activities were measured. Western blot demonstrated a significant decrease in aortal ACE2 and phospho-eNOS protein expression in 12 wk hypertensive db/db mice compared to controls (p<0.001). However, aortal renin, ACE, neprilysin and total eNOS protein expression were not altered in db/db mice. There was a significant increase in plasma ACE activity in db/db mice. In conclusion, down regulation of aortal ACE2 and phospho-eNOS protein expression coupled with increased plasma ACE activity may contribute to the evolution of hypertension in db/db diabetic mice.

Hypotensive mechanism of the extracts and artemetin isolated from Achillea millefolium L. (Asteraceae) in rats

Traditional uses of Achillea millefolium L. (Asteraceae) include the treatment of cardiovascular diseases. In the present study, we used anesthetized rats to assess the hypotensive effect of a hydroethanolic extract (HEAM), and its dichloromethane (DCM), ethyl acetate (EA), butanolic (BT), and dichloromethane-2 (DCM-2) fractions, besides the flavonoid artemetin, isolated from A. millefolium. The oral administration of HEAM (100-300 mg/kg), DCM (20mg/kg), DCM-2 (10-30 mg/kg), but not EA (10 mg/kg) and BT (50 mg/kg) fractions significantly reduced the mean arterial pressure (MAP) of normotensive rats. The phytochemical analysis by NMR (1)H of DCM and DCM-2 fractions revealed high amounts of artemetin, that was isolated and administered by either oral (1.5 mg/kg) or intravenous (0.15-1.5 mg/kg) routes in rats. This flavonoid was able to dose-dependently reduce the MAP, up to 11.47 ± 1.5 mmHg (1.5 mg/kg, i.v.). To investigate if artemetin-induced hypotension was related to angiotensin-converting enzyme inhibition, we evaluated the influence of this flavonoid on the vascular effects of both angiotensin I and bradykinin. Intravenous injection of artemetin (0.75 mg/kg) significantly reduced the hypertensive response to angiotensin I while increased the average length of bradykinin-induced hypotension. Artemetin (1.5 mg/kg, p.o.) was also able to reduce plasma (about 37%) and vascular (up to 63%) ACE activity in vitro, compared to control group. On the other hand, artemetin did not change angiotensin II-induced hypertension. Our study is the first showing the hypotensive effects induced by the extract and fractions obtained from A. millefollium. In addition, our results disclosed that this effect may be, at least in part, associated with high levels of artemetin and its ability to decrease angiotensin II generation in vivo, by ACE inhibition.

Angiotensin I-Converting Enzyme Gln1069Arg Mutation Impairs Trafficking to the Cell Surface Resulting in Selective Denaturation of the C-Domain

BackgroundAngiotensin-converting enzyme (ACE; Kininase II; CD143) hydrolyzes small peptides such as angiotensin I, bradykinin, substance P, LH-RH and several others and thus plays a key role in blood pressure regulation and vascular remodeling. Complete absence of ACE in humans leads to renal tubular dysgenesis (RTD), a severe disorder of renal tubule development characterized by persistent fetal anuria and perinatal death.Methodology/Principal FindingsPatient with RTD in Lisbon, Portugal, maintained by peritoneal dialysis since birth, was found to have a homozygous substitution of Arg for Glu at position 1069 in the C-terminal domain of ACE (Q1069R) resulting in absence of plasma ACE activity; both parents and a brother who are heterozygous carriers of this mutation had exactly half-normal plasma ACE activity compared to healthy individuals. We hypothesized that the Q1069R substitution impaired ACE trafficking to the cell surface and led to accumulation of catalytically inactive ACE in the cell cytoplasm. CHO cells expressing wild-type (WT) vs. Q1069R-ACE demonstrated the mutant accumulates intracellularly and also that it is significantly degraded by intracellular proteases. Q1069R-ACE retained catalytic and immunological characteristics of WT-ACE N domain whereas it had 10–20% of the nativity of the WT-ACE C domain. A combination of chemical (sodium butyrate) or pharmacological (ACE inhibitor) chaperones with proteasome inhibitors (MG 132 or bortezomib) significantly restored trafficking of Q1069R-ACE to the cell surface and increased ACE activity in the cell culture media 4-fold.Conclusions/SignificanceHomozygous Q1069R substitution results in an ACE trafficking and processing defect which can be rescued, at least in cell culture, by a combination of chaperones and proteasome inhibitors. Further studies are required to determine whether similar treatment of individuals with this ACE mutation would provide therapeutic benefits such as concentration of primary urine.

Effects of iron and/or zinc deficiency on blood biochemical parameters in rats

To investigate the effects of iron (Fe) and zinc (Zn) deficiency on blood biochemical parameters (plasma lipids, protein, plasma AST, ALT and ACE activities), forty 4‐week‐old male Sprague‐Dawley rats were assigned into 4 dietary treatment groups of 10 for the 4‐week study: severely Fe‐deficient group (FD), moderately Zn‐deficient group (ZD), severely Fe‐deficient/moderately Zn‐deficient group (FZD), and control group (Control). After 4 weeks on dietary regimen, rats were fasted overnight and anesthetized with diethylether. Blood was collected from the abdominal aorta with heparin. Statistical analysis was conducted using Tukey's simultaneous multiple comparison test. Plasma TG, T‐Cho and FFA concentrations were not significantly different among all treatment groups. Plasma PL concentration of FD and FZD was significantly higher than that of ZD. Compared with Control, plasma total protein and globulin concentrations of FD were significantly higher, and those of ZD tended to decrease. However, the Fe deficiency‐associated alterations were suppressed in the combined deficiency of Fe and Zn. Plasma albumin concentration was not significantly different among all treatment groups. The A/G ratio of FZD was significantly higher than FD. Plasma AST activity of FD was significantly higher than that of Control. Plasma ACE activity of FD, ZD and FZD were significantly higher than that of Control. These data indicate an interaction between Fe and Zn metabolism.