Similar Reductions In Blood Pressure Research Articles

Carotid Artery Hemodynamics: Observing Patient-specific Changes with Amlodipine and Lisinopril by Using MR Imaging Computation Fluid Dynamics

To assess whether using magnetic resonance (MR) imaging combined with computational fluid dynamics (CFD) could reveal changes in common carotid artery (CCA) flow and wall shear stress (WSS) that might contribute to differences in CCA remodeling between amlodipine, a calcium channel blocker, and lisinopril, an angiotensin-converting enzyme inhibitor, despite similar reductions in blood pressure (BP). Institutional review board approval was obtained, and participants gave informed consent. Nine subjects with hypertension were recruited into a double-blind placebo-controlled randomized three-way crossover study to compare the hemodynamic effects of 7 days of treatment with placebo, amlodipine, or lisinopril. After each treatment period, patients underwent CCA ultrasonography, BP measurement, and MR imaging with CFD. Analyses were performed by using repeated-measures analysis of variance, followed by the Tukey test or the Wilcoxon matched-pairs test. Amlodipine and lisinopril lowered BP similarly, but CCA flow rate was significantly higher (P < .01) and distal vascular resistance was lower (P = .016) after amlodipine treatment than after lisinopril treatment. WSS on the inner wall of the CCA was significantly lower after lisinopril treatment than after amlodipine treatment (P = .03). The change in WSS in the CCA correlated with the change in vascular resistance (r = -0.85, P < .001). Amlodipine causes increased blood flow and increased time-averaged WSS in the CCA compared with lisinopril, despite similar reductions in BP. Differences in the subacute hemodynamic effects of amlodipine and lisinopril could contribute to the differences in CCA remodeling seen in long-term studies. http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.10100788/-/DC1.

Aliskiren Alone or in Combination With Hydrochlorothiazide in Patients With the Lower Ranges of Stage 2 Hypertension: The ACQUIRE Randomized Double‐Blind Study

Patients with stage 2 hypertension (systolic blood pressure [SBP] ≥160mm Hg and/or diastolic blood pressure [DBP] ≥100mm Hg) are at high cardiovascular risk and require intensive blood pressure (BP)-lowering therapy. This randomized double-blind study is the first prospective trial specifically designed to evaluate the direct renin inhibitor aliskiren in patients with a mean sitting SBP ≥160 mm Hg and <180mm Hg (the lower ranges of stage 2 systolic hypertension). After a 2- to 4-week washout period, 688 patients were randomized to once-daily aliskiren/hydrochlorothiazide (HCT) 150/12.5mg or aliskiren 150mg for 1 week and then double the doses for 11 weeks. Baseline BP was 167.1/95.0mm Hg. At week 12, both aliskiren/HCT and aliskiren provided substantial BP reductions from baseline (30.0/12.6 mm Hg and 20.3/8.2 mm Hg, respectively). Aliskiren/HCT lowered BP significantly more than aliskiren (least-squares mean between-treatment differences [95% confidence interval] were -9.7 [-12.0 to -7.4] for SBP and -4.5 [-5.8 to -3.2] for DBP; both P<.0001). Similar BP reductions were seen in the subgroups of patients with isolated systolic hypertension and obesity. Aliskiren, with or without HCT, provides clinically significant BP reductions and may therefore be an effective treatment option in patients with stage 2 hypertension.

Different Effects of Aliskiren and Losartan on Fibrinolysis and Insulin Sensitivity in Hypertensive Patients with Metabolic Syndrome

The aim of this study was to compare the effect of aliskiren and losartan on fibrinolysis and insulin sensitivity (IS) in hypertensive patients with metabolic syndrome. After 2-week placebo period, 76 outpatients with mild to moderate hypertension and metabolic syndrome were randomized to aliskiren 300 mg od or losartan 100 mg od for 12 weeks. Clinic blood pressure (BP), plasma PAI-1 antigen, and tPA activity were evaluated after 2, 4, 8, and 12 weeks of treatment. At the end of each treatment period patients performed an euglycemic hyperinsulinemic clamp and IS was assessed by glucose infusion rate (GIR). Both aliskiren and losartan induced a significant and similar SBP/DBP reduction (-15.6/10.7 mmHg and -15.5/10.5 mmHg, p<0.001 vs. baseline, respectively). Both drugs decreased PAI-1 antigen and activity after 2 weeks of treatment; subsequently, only the decreasing effect of aliskiren was sustained throughout the 12 weeks [-7.5 ng/ml (-31%) p<0.05 vs. baseline], while with losartan PAI-1 increased at week 12 [+3.6 ng/ml (+15%), p<0.05 vs. baseline and p<0.01 vs. aliskiren)]. The tPA activity showed no significant change with aliskiren and a decrease with losartan [-0.04 IU/ml (-8%), p<0.05 vs. baseline and p<0.01 vs. aliskiren]. Aliskiren significantly increased GIR [+1.4 mg/min/kg (+28%), p<0.01 vs. baseline] while losartan did not change it [+0.2 mg/min/kg (+4%), NS vs. baseline, p<0.05 vs. aliskiren)]. These results indicated that in this type of patients, despite similar BP reduction, aliskiren improved the fibrinolytic balance as well as IS, while losartan worsened the fibrinolytic balance and did not affect IS. The clinical relevance of these different effects remains to be clarified.

Discovery of Novel Cyanodihydropyridines as Potent Mineralocorticoid Receptor Antagonists

A new 1,4-dihydropyridine 5a, containing a cyano group at the C3 position, was recently reported to possess excellent mineralocorticoid receptor (MR) antagonist in vitro potency and no calcium channel-blocker (CCB) activity. In the present study, we report the structure-activity relationships of this novel series of cyano ester dihydropyridines that resulted in R6 substituted analogues with improved metabolic stability while maintaining excellent MR antagonist activity and selectivity against other nuclear receptors. Further structure optimization with the introduction of five-membered ring heterocycles at R6 resulted in compounds with excellent MR antagonist potency and a suitable pharmacokinetic profile. In vivo studies of a promising tool compound in the Dahl salt-sensitive rat model of hypertension showed similar blood pressure (BP) reduction as the steroidal MR antagonist eplerenone, providing proof-of-concept (POC) for a nonsteroidal, orally efficacious MR antagonist.

HYPOKALEMIA BLUNTS LEFT VENTRICULAR MASS REGRESSION IN HYPERTENSIVE PATIENTS DURING LOSARTAN- OR ATENOLOL-BASED TREATMENT: THE LIFE ECHO-SUBSTUDY: 9D.06

Background: It has been recently reported in hypertensive patients that hypokalemia (HypoK) is associated with persistent ECG left ventricular (LV) hypertrophy. The aim of the present study was to assess the impact of HypoK on echocardiographic LV mass regression in treated hypertensive patients. Methods: We analyzed data from 863 patients from the LIFE echo substudy (age 66 ± 7 years, 41% women) with available serum K+ levels. Patients were dichotomized according to presence of HypoK (i.e. <3.90mmol/L, lowest quartile). LV mass regression after one year of treatment was compared among groups. Results: Patients with HypoK had similar mean age and gender distribution as compared to patients with normal K+ (all p = ns), but higher systolic and diastolic blood pressure (BP) and heart rate (all p < 0.05). There was a similar reduction among groups in both systolic and diastolic BP (p = ns). As shown in figure, in multivariate analysis controlling for differences in age, gender, baseline LV mass index, hydroclorothiazide use before or during the study, baseline BP, and BP change, patients with HypoK showed a significant lower reduction in LV mass as compared to the normal K+ group (p < 0.001). Furthermore, while in patients randomized to Losartan there was a similar significant reduction in LV mass both in the absence and presence of HypoK (p = ns), in the Atenolol group HypoK was associated with a nearly 60% lower LV mass reduction (p < 0.001). Conclusions: Despite similar blood pressure reduction with treatment, patients with HypoK have a significant lower LV mass regression. While Losartan is able to offset the negative impact of HypoK, its presence markedly affects the efficacy of Atenolol.

Differential effects of candesartan and olmesartan on adipose tissue activity biomarkers in type II diabetic hypertensive patients

The aim of this study is to compare the effects of candesartan and olmesartan on insulin sensitivity-related parameters, before and after antihypertensive therapy. After a 4-week washout placebo period, 194 hypertensive (diastolic blood pressure (DBP) > or =80 mm Hg and systolic blood pressure (SBP) > or =130 mm Hg) patients with well-controlled type II diabetes were randomized to receive either 8 mg of candesartan once a day (o.d.) or 10 mg olmesartan o.d. and titrated after 1 month to 16 mg candesartan o.d. or 20 mg olmesartan o.d., respectively; the treatment period had a 1-year duration. We evaluated body weight, body mass index, SBP, DBP, glycated hemoglobin, fasting plasma glucose, M value, adiponectin (ADN), resistin (r), retinol-binding protein 4, visfatin, vaspin and high-sensitivity C-reactive protein (Hs-CRP) at their baseline values and after 6 and 12 months of treatment. We observed no variation in body weight or glycemic profile for either treatment. SBP and DBP were significantly reduced by both treatments (from 144+/-8/88+/-6 to 126+/-5/77+/-4 mm Hg by candesartan (P<0.001) and from 145+/-9/89+/-7 to 128+/-7/79+/-5 mm Hg by olmesartan (P<0.001)) without any difference between them. Retinol binding protein-4, r, and the vaspin value decreased in the candesartan group but not in olmesartan group. The M value, visfatin and ADN increased with candesartan, whereas no significant variations were observed with olmesartan. Both treatments resulted in a similar reduction in Hs-CRP. Although both therapies resulted in similar reductions in blood pressure, candesartan therapy was more effective than olmesartan therapy in improving insulin sensitivity.

Cardiovascular protective effects of nebivolol in Zucker diabetic fatty rats

Although effective in reducing blood pressure, therapy with a first-generation [beta]-blocker is currently controversial in metabolic syndrome due to its negative impact on carbohydrate and lipid metabolism. We evaluated the effects of nebivolol, a third-generation highly selective [beta]-blocker with additional vasodilating activity, versus the traditional [beta]-blocker atenolol in controlling functional and morphological cardiovascular damage in a rat model of metabolic syndrome. During 6 months, Zucker diabetic fatty (ZDF) rats and control lean Zucker rats (LZR) were studied. The experimental groups were: untreated ZDF, ZDF along with nebivolol, ZDF along with atenolol and LZR. Blood pressure, plasma insulin, triglycerides, cholesterol, glucose and platelet aggregation were evaluated. Malondialdehyde, reduced glutathione (GSH)/oxidized glutathione (GSSG) ratio, CuZn superoxide dismutase, catalase and glutathione peroxidase were determined in heart homogenates and transforming growth factor [beta]1 and plasminogen activator inhibitor-1 (PAI-1) expression, by immunohistochemistry (IHC). Vascular reactivity, vascular cell adhesion molecule-1, platelet endothelial cell adhesion molecule-1, PAI-1, enhanced nitric oxide synthase and collagen expression were evaluated in aorta. Nebivolol and atenolol presented a similar reduction in blood pressure. However, nebivolol showed a better lipid profile, preserved left ventricular function, a significant control in left ventricular geometry and moderated left ventricular hypertrophy versus atenolol. Significant reduction in platelet aggregation and a substantial endothelium-dependent and endothelium-independent relaxation in vessels were also shown in the nebivolol group versus atenolol group. Antioxidant defenses were preserved by nebivolol with a reduction in oxidative stress parameters. Vascular cell adhesion molecule-1, platelet endothelial cell adhesion molecule-1, PAI-1 and eNOS were favorably modulated with nebivolol in vessel wall. TGF[beta]1, PAI-1 and accumulation of collagen-III and collagen-I were also diminished in heart with nebivolol. The present study provides substantial information supporting an actual protective role of nebivolol in comparison with atenolol in experimental metabolic syndrome.

Abstract 5419: Hypokalemia Blunts Left Ventricular Mass Regression in Hypertensive Patients During Losartan- or Atenolol-Based Treatment: The LIFE Echo-substudy

Background: It has been reported that hypokalemia (HypoK) is associated with persistent ECG left ventricular (LV) hypertrophy in treated hypertensive patients. The aim of the present study was to assess the impact of HypoK on echocardiographic LV mass regression during aggressive antihypertensive treatment. Methods: We analyzed data from 863 patients in the LIFE echo substudy (age 66±7 years, 41% women) with available serum K + levels. Patients were dichotomized according to presence of HypoK (i.e. &lt;3.90mmol/L, lowest quartile). LV mass regression after one year of treatment was compared among groups. Results: Patients with HypoK had similar mean age and gender distribution to patients with normal K + (all p=ns), but higher systolic and diastolic blood pressure (BP) and heart rate (all p&lt;0.05). After one year, similar reduction among groups in both systolic and diastolic BP (p=ns) was found. In multivariate analysis controlling for differences in age, gender, baseline LV mass, hydroclorothiazide use before or during the study, baseline BP, and BP change, patients with HypoK had a significantly lower regression of LV mass as compared to the normal K + group (p&lt;0.001). Furthermore, while in patients randomized to Losartan (n=434) reduction in LV mass was not significantly different in the absence or presence of HypoK (p=ns), in the Atenolol group HypoK was associated with a nearly 60% lower LV mass reduction (Figure ; p&lt;0.001). Conclusions: Despite similar blood pressure reduction with treatment, patients with HypoK have a lower LV mass regression. While Losartan is able to offset the negative impact of HypoK, its presence markedly affects LV mass reduction on Atenolol-based therapy. Figure. Left ventricular mass reduction after one year of anti-hypertensive treatment according to serum K + levels and treatment arm.

INVEST revisited: review of findings from the International Verapamil SR–Trandolapril Study

The International Verapamil SR–Trandolapril Study (INVEST), a randomized trial of 22,576 predominantly elderly patients with an average 2.7-year follow-up, compared a calcium antagonist-led strategy (verapamil SR plus trandolapril) with a β-blocker-led strategy (atenolol plus hydrochlorothiazide) for hypertension treatment and prevention of cardiovascular outcomes in coronary artery disease patients. Patients received individualized dose and drug titration following a flexible, multi-drug, guideline-based treatment algorithm, with the objective of achieving optimal blood pressure (BP) control individualized for comorbidities (e.g., diabetes). The primary outcome (PO) was first occurrence of death (all-cause), nonfatal myocardial infarction or nonfatal stroke. The strategies resulted in significant and very similar BP reduction, with approximately 70% of patients in both strategies achieving BP control (<140/90 mmHg). Increasing number of office visits with BP in control was associated with reduced risk of the PO. Overall, there was no difference in the PO comparing the strategies; however, new-onset diabetes occurred more frequently in those assigned the atenolol strategy. This report summarizes findings from INVEST and puts them in perspective with our current state of knowledge derived from other large hypertension treatment trials. INVEST findings support that BP reduction is important for prevention of adverse cardiovascular morbidity and mortality, and selection of antihypertensive agents should be based on patient comorbidities and other risk factors (e.g., risk for diabetes) and not necessarily that any one drug be given to all.

Dual blockade of the renin-angiotensin system: are two better than one?

The beneficial effects of blood pressure-lowering treatments on the risks of major cardiovascular events are well established [1]. Interruption of the renin–angiotensin system (RAS) with angiotensin-converting enzyme inhibitors (ACEi) or angiotensin receptor blockers (ARB) has been shown to be an effective strategy for lowering blood pressure. Randomized trials have shown that ACEi can lower blood pressure by an average of 5/2 mmHg and reduce the risks of cardiovascular events and cardiovascular mortality by ∼20% (and total mortality by 10%) [2–6]. ARBs produce similar reductions in blood pressure and vascular events (although fewer patients have received them in randomized trials) [7–9]. Further, RAS blockade has been reliably shown to reduce the risk of kidney disease progression [10–15]. A meta-analysis of ACEi and ARB monotherapy in diabetic nephropathy demonstrated reductions in end-stage renal disease (ESRD) of around one-quarter for both treatments [16]. Similarly, an individual patient data meta-analysis of ACEi in non-diabetic kidney disease showed a relative risk reduction of 31% (95% CI 5–49%). The major trials of ACEi or ARB monotherapy in various patient populations are summarized in Table 1. As shown in Table 1, among patients at a low risk of renal progression ESRD occurs rarely, and only after many years or even decades. This probably explains the lack of renal benefit reported in large general population trials and meta-analyses of such trials [17–19]. Furthermore, there is some evidence that even the relative benefit might depend on baseline risk, making it even less likely that any true benefit could be detected in existing trials [10]. Whether the observed benefits of RAS blockade are only mediatedbytheirbloodpressure-loweringeffectorwhether other effects also play a role remains controversial; there is some evidence that interruption of the RAS provides more benefit than would simply be expected by the degree of blood pressure reduction alone [5,7,20]. It has been suggested that incomplete blockade of the RAS with ACEi or ARB monotherapy can cause a phenomenon called ‘aldosterone escape’, in which the lack of negative feedback from end-products of the RAS causes a reactive increase in renin and consequent increases in angiotensin I and II concentrations which overwhelm the pharmacological blockade [21]. Dual blockade would therefore be attractive as ACEi and ARB inhibit the RAS at different steps. However, there is continuing uncertainty about the balance of benefits and harms of dual RAS blockade, both in terms of cardiovascular risk and progression of kidney disease. This question will be discussed here in the context of recent evidence from randomized controlled trials.

Blood pressure-independent effects of enhanced NO/cGMP signalling and gender on aortic remodelling in experimental renal hypertension

Results SNX led to increases in systolic blood pressure, with lower levels in F rats (F-SNX 129 ± 13 mmHg vs. M-SNX 140 ± 11 mmHg). Bay 41-8543 and hydralazine reduced blood pressure to control levels. Aortic remodelling was characterized by marked media thickening in both SNX groups, with a more pronounced increase in M versus F (127 ± 9 vs. 108 ± 6% of control; p < 0.001). Intima-media ratio was reduced in both uremic groups, with significant sex differences (M-SNX 66 ± 7% vs. F-SNX 80 ± 8% of control; p < 0.01). Furthermore, gender differences were observed in media-to-lumen ratio as indicator of aortic hypertrophy. The ratio was significantly higher in SNX males only (M-SNX 131 ± 9% vs. F-SNX 107 ± 15% of control; p < 0.001). Bay 41-8543 significantly ameliorated media thickness (111 ± 10 vs. 127 ± 9% of control in M; 101 ± 7 vs. 108 ± 6% of control in F; p < 0.05), intima-media ratio (85 ± 10 vs. 66 ± 7% of control in M; 91 ± 6 vs. 80 ± 8% of control in F, p < 0.01) and media-to-lumen ratio (107 ± 9 vs. 131 ± 9% of control in M; p < 0.001). Despite a similar reduction in blood pressure, hydralazine treatment did not alter aortic wall remodelling. These morphological changes were accompanied by elevated collagen I and reduced elastin protein expression at the level of aortic media, with decreased elastin/collagen ratio in untreated SNX groups, as marker of aortic wall stiffening. Bay 41-8543 treatment successfully prevented these molecular alterations (collagen I protein expression: 9.4 ± 0.3 vs. 14.5 ± 1.1% in females and 9.6 ± 0.4 vs. 16.1 ± 1.0% in males), while hydralazine showed no effects. SNX was characterized by increased extracellular matrix turnover with up-regulation of MMP2 and TIMP1 genes, more pronounced in males than in females (M-SNX 1.8 ± 0.1 vs. F-SNX 1.1 ± 0.1 for MMP2; M-SNX 4.2 ± 0.8 vs. F-SNX 2.7 ± 0.6 for TIMP1; both expressed as relative values vs. controls). In the male Bay 41-8543-treated group, expression of these genes was significantly lower (1.4 ± 0.1 MMP2from 4th International Conference of cGMP Generators, Effectors and Therapeutic Implications Regensburg, Germany. 19–21 June 2009

The Effect Of Resistance Training On Vascular Function And Central Blood Pressure In African American Men

PURPOSE: Young African American men have stiffer large central arteries, impaired dilation of smaller peripheral arteries and greater central blood pressure (BP) when compared to their white peers. The purpose of this study was to examine the effect of resistance exercise training (RT) on vascular function and central BP in young (age 22 yrs) African American and white men. METHODS: Vascular and hemodynamic measures were made in 19 African American and 18 white men at baseline and following 6-weeks of RT. Carotid BP and carotid artery beta-stiffness were measured by tonometry and ultrasonography respectively. Aortic BP and augmentation index (AIx) were measured by radial artery tonometry and a generalized transfer function. Aortic and brachial stiffness were measured by pulse wave velocity (PWV). Brachial blood flow was assessed by Doppler ultrasonography. Forearm blood flow was measured by strain-gauge plethysmography at rest and during reactive hyperemia (RH) induced by 5-min of upper arm occlusion. RESULTS: There were similar reductions in aortic systolic BP, carotid systolic BP, forearm vascular resistance and brachial vascular resistance in both African American and white men following training (p<0.05). There were similar increases in peak forearm blood flow and forearm blood flow area under the curve measured during RH in both African American and white men following training (p<0.05). There were no changes in brachial systolic BP, carotid stiffness, aortic AIx, aortic PWV, and brachial PWV in either group (p>0.05). CONCLUSIONS: RT reduced central BP while having no effect on brachial BP in young African American and white men. Resistance exercise training appears to be a useful lifestyle intervention for improving peripheral vascular function while not detrimentally affecting central vascular function in young African American men.

Clustered metabolic abnormalities blunt regression of hypertensive left ventricular hypertrophy: the LIFE study

Background and aims Clusters of metabolic abnormalities resembling phenotypes of metabolic syndrome predicted outcome in the LIFE study, independently of single risk markers, including obesity, diabetes and baseline ECG left ventricular hypertrophy (LVH). We examined whether clusters of two or more metabolic abnormalities (MetAb, including obesity, high plasma glucose without diabetes, low HDL-cholesterol) in addition to hypertension were associated to levels of ECG LVH reduction comparable to that obtained in hypertensive subjects without or with only one additional metabolic abnormality (no-MetAb). Methods and results We studied 5558 non-diabetic participants without MetAb (2920 women) and 1235 with MetAb (751 women) from the LIFE-study cohort. MetAb was defined by reported LIFE criteria, using partition values from the ATPIII recommendations. Time-trends of Cornell voltage–duration product (CP) over 5 years was assessed using a quadratic polynomial contrast, adjusting for age, sex, prevalent cardiovascular disease and treatment arm (losartan or atenolol). At baseline, despite similar blood pressures, CP was greater in the presence than in the absence of MetAb ( p < 0.0001). During follow-up, despite similar reduction of blood pressure, CP decreased less in patients with than in those without MetAb, even after adjustment for the respective baseline values (both p < 0.002). Losartan was more effective than atenolol in reducing CP independently of MetAb. Conclusions Clusters of metabolic abnormalities resembling phenotypes of metabolic syndrome are related to greater initial ECG LVH in hypertensive patients with value of blood pressure similar to individuals without metabolic abnormalities, and are associated with less reduction of ECG LVH during antihypertensive therapy, potentially contributing to the reported adverse prognosis of metabolic syndrome.

Resistance exercise training reduces central blood pressure and improves microvascular function in African American and white men

Objective African American men have stiffer large central arteries and impaired dilation of smaller peripheral arteries when compared to their white peers. The purpose of this study was to examine the effect of resistance exercise training (RT) on vascular function and central blood pressure (BP) in young (22 years) African American and white men. Methods Vascular and hemodynamic measures were made in 19 African American and 18 white men at baseline and following 6-weeks of RT. Carotid BP and carotid/brachial artery β-stiffness were measured by tonometry and ultrasonography, respectively. Aortic BP was measured by radial artery tonometry and a generalized transfer function. Aortic stiffness was measured by pulse wave velocity (PWV). Forearm blood flow (FBF) was measured by strain-gauge plethysmography before and during reactive hyperemia (RH) induced by 5-min of brachial artery occlusion. Results There were similar reductions in central BP and similar increases in FBF–RH in both African American and white men following RT ( p < 0.05). There were no changes in brachial systolic BP, carotid stiffness, and aortic PWV in either group ( p > 0.05). There was an increase in brachial stiffness in African American but not white men following RT ( p < 0.05). Conclusions RT led to reductions in central BP and increases in microvascular endothelial function with no effect on central artery stiffness in both groups of young men. RT increased brachial stiffness in African American men. Measurement of conventional brachial BP does not capture the central hemodynamic and vascular response to exercise training due to disparate racial changes in regional vascular properties.

Differential Effects of ChlorthalidoneVersusSpironolactone on Muscle Sympathetic Nerve Activity in Hypertensive Patients

Previous studies in rats indicated that thiazide-type diuretics reduced blood pressure (BP) and triggered baroreflex-mediated increase in sympathetic nerve activity (SNA), whereas spironolactone exerted central sympathoinhibitory action in addition to diuretic effects. The objectives were to determine effects of spironolactone and chlorthalidone on SNA and the role of SNA on diuretic-induced insulin resistance in human hypertension. We conducted a randomized crossover study in 23 untreated hypertensive patients in which we measured muscle SNA at baseline, after 1 and 3 months of chlorthalidone (12.5-25 mg/d), and after 1 and 3 months of spironolactone (50-75 mg/d). Ambulatory BP, baroreflex sensitivity, and indices of insulin resistance were also assessed at baseline and after 3 months of each drug treatment. Chlorthalidone caused a similar reduction in ambulatory BP from baseline when compared with spironolactone (11 +/- 2/4 +/- 2 and 10 +/- 2/4 +/- 2 mm Hg, respectively). However, chlorthalidone increased SNA by 23% (P < 0.01) within 1 month of treatment, whereas spironolactone had no effect in the same subjects. SNA continued to be elevated after 3 months of chlorthalidone when compared with baseline and spironolactone. Baroreflex control of SNA was unaffected by either drug. Chlorthalidone increased indices of insulin resistance, which were significantly correlated with increases in SNA from baseline, whereas spironolactone had no effect in the same subjects. Our data suggest that chlorthalidone, the first-line drug therapy for hypertension, causes persistent activation of sympathetic nervous system and insulin resistance in hypertensive patients. These side effects, however, are avoided by spironolactone despite similar reduction in BP.

Urgent management of quadriplegia following Sichuan earthquake under field condition

Objective: Clonidine, by activating peripheral α-adrenoceptors, produces transient pressor response after i. v. injection in anesthetized animals. Moxonidine, with at least 40-fold higher affinity to I1-imidazoline receptors than to α2-adrenoceptors, produces also a transient pressor response. This work was designed to investigate whether I1-imidazoline receptors are involved in this pressor effect of moxonidine. Methods: Female spontaneously hypertensive rats (SHRs, aged 14-16 weeks) were anesthetized with urethane. To observe the transient pressor responses, moxonidine 0.1, 0.3, 1.0 mg/kg (intravenous, i. v.), 2.0 μg (intracerebroventricular, i. c. v.) and 1.0, 10.0 mg/kg (intragastric, i. g.) were administrated in different groups of rats. To evaluate the roles of α2-adrenoceptors, α2-adrenoceptors and I1-imidazoline receptors in the transient pressor responses to moxonidine, prazosin (10.0 μg/kg), yohimbine (2.0 mg/kg), phentolamine (0.2 mg/kg), idazoxan (1.0 mg/kg) or yohimbine + iclazoxan (2.0 mg/kg + 1.0 mg/kg) were intravenously given to the animals before moxonidine 0.3 mg/kg (i. v.). Results: It was found that i. v. moxonidine produced a greater pressor response than clonidine when producing a similar reduction of blood pressure. This effect of moxonidine was not influenced by prazosin, but was partly inhibited by yohimbine, phentulamine or idazoxan, and completely blocked by the combination of yohimbine and idzaxon. Neither i. c. v. injection nor i. g. administration of moxonidine induced transient pressor responses. Conclusion: The transient pressor response of i. v. moxonidine is mediated by both peripheral I1-imidazoline receptors and α2-adrenoceptors.

Continuous Activation of Renin-Angiotensin System Impairs Cognitive Function in Renin/Angiotensinogen Transgenic Mice

We examined the possibility that continuous activation of the human brain renin-angiotensin system causes cognitive impairment, using human renin (hRN) and human angiotensinogen (hANG) gene chimeric transgenic (Tg) mice. Cognitive function was evaluated by the shuttle avoidance test once a week from 10 to 20 weeks of age. The avoidance rate in wild-type mice gradually increased. In contrast, the avoidance rate in chimeric hRN/hANG-Tg mice also increased; however, no further increase in avoidance rate was observed from 14 weeks of age, and it decreased thereafter. Cerebral surface blood flow was markedly reduced in 20-week-old hRN/hANG-Tg mice. Superoxide anion production in the brain was already higher in 10-week-old hRN/hANG-Tg mice and further increased thereafter with an increase in NADPH oxidase activity. Moreover, expression of p47(phox) and Nox4 in the brain of hRN/hANG-Tg mice also increased. Administration of an angiotensin II type 1 receptor blocker, olmesartan (5.0 mg/kg per day), attenuated the increase in blood pressure and ameliorated cognitive decline with enhancement of cerebral surface blood flow and a reduction of oxidative stress in hRN/hANG-Tg mice. On the other hand, hydralazine (0.5 mg/kg per day) did not improve the decrease in avoidance rate, and did not influence cerebral surface blood flow or oxidative stress in hRN/hANG-Tg mice, in spite of a similar reduction of blood pressure to that by olmesartan. Moreover, we observed that treatment with Tempol improved impaired cognitive function in hRN/hANG-Tg mice. These results suggest that continuous activation of the brain renin-angiotensin system impairs cognitive function via stimulation of the angiotensin II type 1 receptor with a decrease in cerebral surface blood flow and an increase in oxidative stress.

“Pulse” Treatment With High-Dose Angiotensin Blocker Reverses Renal Arteriolar Hypertrophy and Regresses Hypertension

One ultimate goal of hypertension therapy is to cause permanent reversal ("regression") of already established hypertension. Our aim was to examine whether high-dose "pulse" treatment with a renin-angiotensin system inhibitor could cause regression of established hypertension and to link this action to reversal of arteriolar hypertrophy and changes in vascular matrix metalloproteinase activities. First, 16-week-old male spontaneously hypertensive rats (n=60) were pulse treated for 2 weeks with high-dose angiotensin-converting enzyme inhibitor (enalapril), angiotensin receptor blocker (candesartan), calcium channel blocker (nifedipine), or vasodilator (hydralazine) with or without salt restriction, and the long-term effects on blood pressure were examined. Second, spontaneously hypertensive rats were treated with angiotensin receptor blocker or calcium channel blocker, and the effects on renal gene expressions, arteriolar structure, and vascular matrix metalloproteinase were compared. Treatment of spontaneously hypertensive rats with different antihypertensive agents caused apparently similar reductions in blood pressure during the course of the pulse treatment, within the limitations of the tail-cuff method. After cessation of medications, blood pressure in the rats treated with renin-angiotensin system inhibitor remained reduced by >30 to 40 mm Hg for 4 months. No such effect was seen with calcium channel blocker or vasodilator. The 2-week angiotensin receptor blocker treatment induced a marked reversal of the arteriolar hypertrophy specifically in the small (30 to 100 microm) renal arterioles, together with increased expression and activity of matrix metalloproteinase-13. In conclusion, transient high-dose pulse treatment with angiotensin receptor blocker caused changes in vascular matrix metalloproteinase activity, specific reversal of renal arteriolar hypertrophy, and regression of hypertension in spontaneously hypertensive rats.

Add-on manidipine versus amlodipine in diabetic patients with hypertension and microalbuminuria: the AMANDHA study

The aim of this study was to compare the efficacy and safety of adding manidipine 20 mg versus amlodipine 10 mg to the treatment of diabetic patients with uncontrolled hypertension and microalbuminuria despite full-dose treatment with a renin–angiotensin system blocker for at least 6 months. Patients were randomized to receive manidipine (n = 61) or amlodipine (n = 30) in a 2:1 ratio for 6 months and monitored for microalbuminuria for an additional extension phase of 18 months. Manidipine and amlodipine decreased blood pressure values to a similar extent. Urinary albumin excretion was reduced by 65.5% with manidipine versus 20% with amlodipine (p < 0.01) at 6 months and 62.7 versus 16.6% (p < 0.01) at the end of the extension phase. Manidipine was better tolerated than amlodipine. Thus, the addition of manidipine, but not amlodipine, resulted in a large reduction in the urinary albumin excretion rate despite similar blood pressure reductions.

Strict angiotensin blockade prevents the augmentation of intrarenal angiotensin II and podocyte abnormalities in type 2 diabetic rats with microalbuminuria

Beneficial effects of angiotensin II type 1 receptor blockers have been indicated for patients with diabetic nephropathy. We investigated the effects of an angiotensin II type 1 receptor blocker, telmisartan, on intrarenal angiotensin II levels and the progression of albuminuria or glomerular injury in type 2 diabetic Otsuka Long-Evans Tokushima Fatty rats with microalbuminuria. Otsuka Long-Evans Tokushima Fatty rats were randomly treated with telmisartan (10 mg/kg/day, orally), hydralazine (25 mg/kg/day in drinking water) or vehicle from the initiation of albuminuria (13 weeks old). At this age, Otsuka Long-Evans Tokushima Fatty rats showed low but detectable albuminuria (1.0 +/- 0.1 mg/day) and higher systolic blood pressure, postprandial blood glucose and kidney angiotensin II levels than age-matched nondiabetic Long-Evans Tokushima Otsuka rats. At 35 weeks of age, vehicle-treated Otsuka Long-Evans Tokushima Fatty rats did not show apparent glomerular injury or tubulointerstitial fibrosis but did exhibit severe albuminuria (72.6 +/- 5.9 mg/day) and accumulation of cytoplasmic granules containing albumin in podocytes. Otsuka Long-Evans Tokushima Fatty rats also showed higher systolic blood pressure, postprandial blood glucose, collagen gene expression, desmin staining (a marker of podocyte injury) and angiotensin II levels than Long-Evans Tokushima Otsuka rats. Treatment with telmisartan did not affect postprandial blood glucose but decreased systolic blood pressure, collagen gene expression, desmin staining and angiotensin II levels. Telmisartan also prevented the development of albuminuria (0.6 +/- 0.1 mg/day at 35 weeks old) and accumulation of cytoplasmic granules. Hydralazine treatment resulted in a similar reduction in systolic blood pressure and partially attenuated the albuminuria (35.4 +/- 1.8 mg/day at 35 weeks old) but did not affect the other parameters. The present results suggest the contribution of augmented intrarenal angiotensin II levels to the initiation and progression of albuminuria as well as podocyte abnormalities in type 2 diabetic rats. Angiotensin II blockade may inhibit the transition from microalbuminuria to overt nephropathy through prevention of intrarenal angiotensin II augmentation, independently of changes in blood pressure and glucose levels.