Long-term Angiotensin-converting Enzyme Inhibition Research Articles

Genetically proxied therapeutic inhibition of antihypertensive drug targets and risk of common cancers: A mendelian randomization analysis.

Epidemiological studies have reported conflicting findings on the potential adverse effects of long-term antihypertensive medication use on cancer risk. Naturally occurring variation in genes encoding antihypertensive drug targets can be used as proxies for these targets to examine the effect of their long-term therapeutic inhibition on disease outcomes. We performed a mendelian randomization analysis to examine the association between genetically proxied inhibition of 3 antihypertensive drug targets and risk of 4 common cancers (breast, colorectal, lung, and prostate). Single-nucleotide polymorphisms (SNPs) in ACE, ADRB1, and SLC12A3 associated (P < 5.0 × 10-8) with systolic blood pressure (SBP) in genome-wide association studies (GWAS) were used to proxy inhibition of angiotensin-converting enzyme (ACE), β-1 adrenergic receptor (ADRB1), and sodium-chloride symporter (NCC), respectively. Summary genetic association estimates for these SNPs were obtained from GWAS consortia for the following cancers: breast (122,977 cases, 105,974 controls), colorectal (58,221 cases, 67,694 controls), lung (29,266 cases, 56,450 controls), and prostate (79,148 cases, 61,106 controls). Replication analyses were performed in the FinnGen consortium (1,573 colorectal cancer cases, 120,006 controls). Cancer GWAS and FinnGen consortia data were restricted to individuals of European ancestry. Inverse-variance weighted random-effects models were used to examine associations between genetically proxied inhibition of these drug targets and risk of cancer. Multivariable mendelian randomization and colocalization analyses were employed to examine robustness of findings to violations of mendelian randomization assumptions. Genetically proxied ACE inhibition equivalent to a 1-mm Hg reduction in SBP was associated with increased odds of colorectal cancer (odds ratio (OR) 1.13, 95% CI 1.06 to 1.22; P = 3.6 × 10-4). This finding was replicated in the FinnGen consortium (OR 1.40, 95% CI 1.02 to 1.92; P = 0.035). There was little evidence of association of genetically proxied ACE inhibition with risk of breast cancer (OR 0.98, 95% CI 0.94 to 1.02, P = 0.35), lung cancer (OR 1.01, 95% CI 0.92 to 1.10; P = 0.93), or prostate cancer (OR 1.06, 95% CI 0.99 to 1.13; P = 0.08). Genetically proxied inhibition of ADRB1 and NCC were not associated with risk of these cancers. The primary limitations of this analysis include the modest statistical power for analyses of drug targets in relation to some less common histological subtypes of cancers examined and the restriction of the majority of analyses to participants of European ancestry. In this study, we observed that genetically proxied long-term ACE inhibition was associated with an increased risk of colorectal cancer, warranting comprehensive evaluation of the safety profiles of ACE inhibitors in clinical trials with adequate follow-up. There was little evidence to support associations across other drug target-cancer risk analyses, consistent with findings from short-term randomized controlled trials for these medications.

240-LB: Angiotensin-Converting Enzyme and Type 2 Diabetes Risk: A Mendelian Randomization Study

The causal relationship between angiotensin-converting enzyme (ACE) inhibition and protection from type 2 diabetes (T2D) remains uncertain. While three large randomized control trials (RCTs) suggested a protective effect of ACE inhibitors compared to placebo, three other RCTs failed to observe an effect, including the only trial dedicated to this question. We hypothesized that ACE concentration-lowering genetic variants could be used to infer the pharmacological effect of ACE inhibitors on T2D risk using a Mendelian Randomization (MR) approach. We first assessed the association between T2D prevalence and ACE serum level in the Outcome Reduction with Initial Glargine Intervention (ORIGIN) trial (N=8,197). We next investigated whether genetically lowered ACE level was causally linked to the risk of T2D using (i) a two-sample MR analysis applied to the DIAbetes Genetics Replication And Meta-analysis consortium (n=26,676 T2D cases; 132,532 controls), and (ii) an ACE concentration-lowering genetic risk score in the UK Biobank cohort (N=341,872). We then compared the genetically determined effect of lower ACE level on T2D risk to the pharmacological inhibition of ACE vs. placebo, which was evaluated through a meta-analysis of six RCTs (N=31,200). Lower ACE serum level was associated with reduced T2D prevalence (OR, 0.89; 95% CI, 0.82-0.96; P=3.50x10-3) in the ORIGIN trial. Through MR analyses, a 1 SD lower genetically determined ACE level predicted a lower risk of T2D (OR, 0.92; 95% CI, 0.89-0.95; P=1.79x10-7). This result was replicated in the UK Biobank (OR, 0.97; 95% CI, 0.96-0.99, P=8.73x10-4). RCT meta-analysis showed a reduction in T2D incidence on ACE inhibitors vs. placebo (OR, 0.76; 95% CI, 0.60-0.97; P=2.59x10-2), which was consistent with the findings from MR analyses (P for comparison=0.95). Our results support a protective effect of long-term ACE inhibition on T2D risk and suggest to consider patient's risk for T2D when prescribing blood-pressure lowering drugs. Disclosure M. Pigeyre: None. J. Sjaarda: None. M. Chong: None. S. Hess: None. J. Bosch: Advisory Panel; Self; Bayer AG. S. Yusuf: None. H. Gerstein: Advisory Panel; Self; Abbott, AstraZeneca, Boehringer Ingelheim International GmbH, Eli Lilly and Company, Janssen Pharmaceuticals, Inc., Merck &amp; Co., Inc., Novo Nordisk A/S, Sanofi. Research Support; Self; AstraZeneca, Eli Lilly and Company, Merck &amp; Co., Inc., Novo Nordisk A/S, Sanofi. Other Relationship; Self; AstraZeneca, Boehringer Ingelheim International GmbH, Eli Lilly and Company, Sanofi. G. Pare: Consultant; Self; Amgen Inc., Bristol-Myers Squibb Company, Lexicomp, Sanofi. Research Support; Self; Canada Research Chair in Genetic and Molecular Epidemiology, CISCO Professorship in Integrated Health Biosystems, Sanofi. Funding Sanofi; Canadian Institutes of Health Research

Chronic kidney disease: cardiac and renal angiotensin‐converting enzyme (ACE) 2 expression in rats after subtotal nephrectomy and the effect of ACE inhibition

Renin-angiotensin system blockade slows but does not prevent the cardiovascular complications of chronic kidney disease (CKD). Angiotensin-converting enzyme (ACE) 2 is differentially regulated in acute kidney injury, with increased cardiac ACE2 but decreased kidney ACE2 levels. This study investigated the effect of long-term ACE inhibition on cardiac and renal ACE2 in rats with CKD induced by subtotal nephrectomy (STNx). Sprague-Dawley rats had sham (control) or STNx surgery. Control rats received vehicle (n = 9) and STNx rats ramipril (1 mg kg(-1) day(-1); n = 10) or vehicle (n = 10) for 28 days. Subtotal nephrectomy resulted in impaired creatinine clearance (P < 0.05), proteinuria (P < 0.05), renal fibrosis (P < 0.05) and reduced renal cortical ACE2 mRNA (P < 0.05) and activity (P < 0.05). In rats with CKD, ramipril improved creatinine clearance (P < 0.05) and was associated with an increase in cortical but not medullary ACE2 activity (P < 0.05). Compared with control rats, STNx rats were hypertensive (P < 0.01), with increased left ventricular end-diastolic pressure (LVEDP; P < 0.01), left ventricular hypertrophy (LVH; P < 0.05) and interstitial (P < 0.05) and perivascular fibrosis (P < 0.01). In rats with CKD, ramipril decreased blood pressure (P < 0.001) and reduced LVEDP (P < 0.01), LVH (P < 0.01) and perivascular fibrosis (P < 0.05) but did not significantly reduce interstitial fibrosis. There was no change in cardiac ACE2 in rats with CKD compared with control rats. In rats with CKD, ACE inhibition had major benefits to reduce blood pressure and cardiac hypertrophy and to improve creatinine clearance, but did not significantly impact on cardiac ACE2, cardiac interstitial fibrosis, renal fibrosis or proteinuria. Thus, in rats with CKD, renal ACE2 deficiency and lack of activation of cardiac ACE2 may contribute to the progression of cardiac and renal tissue injury. As long-term ACE inhibition only partly ameliorated the adverse cardio-renal effects of CKD, adjunctive therapies that lead to further increases in ACE2 activity may be needed to combat the cardio-renal complications of CKD.

ACE Inhibition Reduces Infarction in Normotensive but Not Hypertensive Rats: Correlation with Cortical ACE Activity

Angiotensin-converting enzyme (ACE) inhibition can reduce stroke risk by up to 43% in humans and reduce the associated disability, and hence understanding the mechanism of improvement is important. In animals and humans, these effects may be independent of the blood pressure-lowering effects of ACE inhibition. Normotensive (Wistar-Kyoto (WKY)) and hypertensive (spontaneously hypertensive rat (SHR)) animals were treated with the ACE inhibitors ramipril or lisinopril for 7 or 42 days before 2 hours of transient middle cerebral artery occlusion (MCAo). Blood pressure, serum ACE, and blood glucose levels were measured and stroke infarct volume was recorded 24 hours after stroke. Despite greater reductions in blood pressure, infarct size was not improved by ACE inhibition in hypertensive animals. Short-term ACE inhibition produced only a modest reduction in blood pressure, but WKY rats showed marked reductions in infarct volume. Long-term ACE inhibition had additional reductions in blood pressure; however, infarct volumes in WKY rats did not improve further but worsened. WKY rats differed from SHR in having marked cortical ACE activity that was highly sensitive to ACE inhibition. The beneficial effects of ACE inhibition on infarct volume in normotensive rats do not correlate with changes in blood pressure. However, WKY rats have ACE inhibitor-sensitive cortical ACE activity that is lacking in the SHR.

Reducing blood pressure in SHR with enalapril provokes redistribution of NHE3, NaPi2, and NCC and decreases NaPi2 and ACE abundance

To determine the effects of long-term angiotensin-converting enzyme inhibition (ACEI) and blood pressure (BP) lowering on renal sodium transporter abundance and distribution in spontaneously hypertensive rats (SHR), 9-wk SHR were treated with enalapril (30 mg.kg(-1).day(-1)) for 4 wk. BP decreased from 156 +/- 4 to 96 +/- 8 mmHg. Na(+)/H(+) exchanger isoform 3 (NHE3) and Na(+)-P(i) cotransporter type 2 (NaPi2) localized to the body of the microvilli (MV) in normotensive rat strains. In untreated SHR, NHE3 partially retracted from the body to base of the MV and NaPi2 retracted to subapical vesicles. After enalapril treatment of SHR, NHE3 fully retracted to the base of the MV and, by density gradient fractionation, NHE3, NaPi2, dipeptidyl peptidase IV, myosin VI, Na-Cl cotransporter, and cortical Na-K-Cl cotransporter redistributed from low-density (apical enriched) to high-density (endosome enriched) membranes. Enalapril decreased total abundance of myosin VI (to 0.51 +/- 0.18 of untreated), ACE (0.67 +/- 0.22), and cortical NaPi2 (0.83 +/- 0.10). Normalizing SHR BP with HRH (7.5 mg/day hydralazine, 0.15 mg/day reserpine, and 3 mg/day hydrochlorothiazide) did not change Na(+) transporter density distribution or abundance. We conclude that lowering BP to normal levels in SHR does not normalize Na(+) transporter distribution, rather, chronic ACEI treatment provokes retraction of Na(+) transporters and associated proteins from transport-relevant domains of apical membranes and/or reduces their abundance.

Pulsology Reloaded

The Losartan Intervention For Endpoint reduction in hypertension (LIFE) Study,1 the Second Australian National Blood Pressure Trial (ANBP2),2 and the Anglo-Scandinavian Cardiovascular Outcome Trials3 have shown that different antihypertensive treatments may have different impacts on the rate of events in hypertension while achieving comparable brachial blood pressure (BP) reduction. Thus, although brachial BP estimation by classic Riva–Rocci cuff sphygmomanometer and the Korotkoff auscultatory technique have provided almost all of our knowledge on epidemiology, prognosis, and treatment of hypertension,4,5 recent trials1–3 are revealing intrinsic limitations of the conventional approach, because the real goal of treatment in hypertension is the reduction in the number and the rate of untoward events. More recently, the Conduit Artery Function Evaluation (CAFE) Study6 described higher central BP as a key factor explaining the greater number and rate of events with atenolol than with amlodipine plus perindopril. Central pressure waveform and BP values can be estimated by applanation tonometry, a method supported by solid theoretical principles and modeling studies in experimental settings.7 Analysis of the systolic portion of the carotid pressure waveform allows for obtaining indices of the arterial viscous-elastic properties that correlate with end-organ damage and clinical outcomes in hypertension.8 Therefore, the indices of arterial waveform reflection and mechanics and central BP assessed by applanation tonometry have the potential to add significant information for risk stratification beyond and above brachial BP. In fact, the conclusions of the CAFE Study were well received.9 In addition, applanation tonometry has also been associated with 2D-guided M-mode vascular ultrasonography to assess simultaneously the viscous-elastic properties of the carotid artery, the intima–media thickness, and quantification of atherosclerosis.8 Assessment of cardiovascular target organ damage is curial for a global risk assessment …

Aldosterone antagonists: Silver bullet or just sodium excretion and potassium retention?

ACE inhibitors or AT(1) antagonists are powerful therapeutic strategies to slow the progression of renal disease. However, they provide only imperfect protection since they cannot always prevent end-stage renal failure. Innovative approaches are needed to keep patients with chronic kidney disease off dialysis. Blockade of the aldosterone pathway may prove to be such a beneficial therapeutic concept.

Correlates of ACE activity in macroalbuminuric type 2 diabetic patients treated with chronic ACE inhibition

The activity of the renin-angiotensin-aldosterone system (RAAS) plays an important role in the development and progression of diabetic nephropathy. However, the effect of angiotensin-converting enzyme (ACE) inhibition on the RAAS appears to be modulated by a number of factors including the I/D polymorphism of the ACE genotype. In this study, we attempted to find independent correlates of ACE activity in 121 macroalbuminuric type 2 diabetic Iranian patients under chronic ACE inhibition. Both univariate and multivariate analyses were used. The presence of the D allele was independently associated with significantly higher levels of ACE activity (with the II genotype as reference, P < 0.001, B = 27.3, 95% CI = 17.6-37.1), and this association was not eliminated by potentially confounding variables. In conclusion, the D allele is a significant independent correlate of ACE activity in macroalbuminuric type 2 diabetic Iranian patients under long-term ACE inhibition.

Prevention of cardiovascular events in end-stage renal disease: Results of a randomized trial of fosinopril and implications for future studies

Cardiovascular events (CVEs) are the leading cause of death in chronic hemodialysis patients. Results of trials in non-end-stage renal disease (ESRD) patients cannot be extrapolated to patients with ESRD. It is critical to test cardiovascular therapies in these high-risk patients who are usually excluded from major cardiovascular trials. The study objective was to evaluate the effect of fosinopril on CVEs in patients with ESRD. Eligible patients were randomized to fosinopril 5 mg titrated to 20 mg daily (n=196) or placebo (n=201) plus conventional therapy for 24 months. The primary end point was combined fatal and nonfatal first major CVEs (cardiovascular death, resuscitated death, nonfatal stroke, heart failure, myocardial infarction, or revascularization). No significant benefit for fosinopril was observed in the intent to treat analysis (n=397) after adjusting for independent predictors of CVEs (RR=0.93, 95% confidence interval (CI) 0.68-1.26, P=0.35). The per protocol secondary supportive analysis (n=380) found a trend towards benefit for fosinopril (adjusted RR=0.79 (95% CI 0.59-1.1, P=0.099)). In the patients who were hypertensive at baseline, systolic and diastolic blood pressures were significantly decreased in the fosinopril as compared to the placebo group. After adjustment for risk factors, trends were observed suggesting fosinopril may be associated with a lower risk of CVEs. These trends may have become statistically significant had the sample size been larger, and these findings warrant further study.

Ramipril Treatment Protects Against Nitrate-induced Oxidative Stress in eNOS???/??? Mice: An Implication of the NADPH Oxidase Pathway

The development of nitrate tolerance has been found to be associated with vascular production of superoxide anion (O2-*), generated mainly by the eNOS and NADPH oxidase pathways. The aim of our study was to investigate whether long-term angiotensin-converting enzyme inhibition by ramipril is able to protect against nitrate tolerance in the aortas of eNOS-deficient (eNOS-/-) mice and to assess the implication of the NADPH oxidase pathway. Therefore, 3 types of treatment were given to wild-type (WT) and eNOS-/- mice: group 1 received ramipril for 5 weeks and a co-treatment with ramirpil plus nitroglycerine (NTG) during the last 4 days, group 2 received only NTG, and group 3 served as control. Relaxations to NTG (0.1 nmol/L to 0.1 mmol/L) were determined on U44619, a thromboxane analogue, precontracted rings, and O2-* production were assessed on aorta homogenates with the lucigenin-enhanced chemiluminescence technique. Cyclic guanosine monophosphate and reverse-transcriptase-polymerase chain reaction analyses were performed on whole mouse aortas. In WT group 2, the concentration-effect curves to NTG were significantly shifted to the right: the pD2 was 6.16 +/- 0.17 (n = 6) vs 6.81 +/- 0.10 (n = 6) in WT group 3 (not exposed to NTG; P < 0.05) and O2-* production was enhanced from 100% +/- 11% (n = 9) to 191% +/- 21% (n = 6; P < 0.01). In contrast, in WT group 1, the rightward shift was abolished: the pD2 value was 6.73 +/- 0.13 (n = 6; NS vs group 3 WT) and O2-* production was 117% +/- 6% (n = 7; NS vs group 3 WT). In eNOS groups 1 and 3, similar data were observed: the pD2 values were 7.58 +/- 0.08 and 7.38 +/- 0.11 (NS) vs 6.89 +/- 0.20 in eNOS group 2 (n = 6; P < 0.01). In the WT mice aortas, ramipril treatment significantly increased the cyclic guanosine monophosphate levels (reflecting nitric oxide availability), which returned to control values after in vivo co-treatment with a bradykinin BK2 antagonist (Icatibant). In both strains, candesartan, an AT1 blocker, was also able to protect against the development of nitrate tolerance. Moreover, before NTG exposure, ramipril treatment decreased p22phox and gp91phox (essential NADPH oxidase subunits) mRNA expression in aortas from both mice strains. In conclusion, long-term ramipril treatment in mice protects against the development of nitrate tolerance by counteracting NTG-induced increase in O2 production, which involves a direct interaction with the NADPH oxidase pathway and seems to be completely independent of the eNOS pathway.

Brachial Pressure–Independent Reduction in Carotid Stiffness After Long-Term Angiotensin-Converting Enzyme Inhibition in Diabetic Hypertensives

Hypertension and diabetes are associated with an increased arterial stiffness. A direct blood pressure-independent effect of angiotensin-converting enzyme inhibitors on arterial stiffness has never been unequivocally demonstrated. In this mechanistic study, we used an experimental design in which patients responding to 1 month treatment with 4 mg perindopril were randomized double-blind to either 4 mg perindopril or 8 mg perindopril for 6 months. We determined carotid distensibility with echotracking and applanation tonometry at baseline and after the 7-month treatment period in 57 essential hypertensive patients with type 2 diabetes (age 63+/-7 years). We monitored ambulatory blood pressure at baseline and after treatment. After 7 months treatment, 24-hour ambulatory blood pressure significantly decreased, with no significant difference between 4 mg and 8 mg perindopril. Carotid distensibility increased more after 8 mg perindopril compared with 4 mg perindopril (8 mg: from 13.1+/-5.9 to 16.0+/-6.7 kPa(-1)x10(-3); 4 mg: from 13.2+/-5.2 to 12.7+/-5.9 kPa(-1)x10(-3); ANOVA, dose-period interaction, P<0.05). Carotid internal diameter and elastic modulus were significantly lower after 8 mg perindopril compared with 4 mg perindopril, independent of blood pressure reduction. These results indicate a dose-dependent and blood pressure-independent reduction in carotid stiffness under chronic treatment with an angiotensin-converting enzyme inhibitor. They suggest that arterial distensibility was increased through an inward remodeling, leading to a reduction in wall stress, thus reducing elastic modulus. They also suggest that long-term administration of high doses (8 mg) of perindopril is required to improve carotid structure and function in hypertensive patients with type 2 diabetes.

Effects of long-term angiotensin converting enzyme inhibition on cardiovascular variability in aging rats

We studied the effects of chronic (4 weeks) angiotensin converting enzyme inhibition with captopril on arterial pressure (AP) and heart rate (HR) variability, as well as on cardiac baroreflex sensitivity (BRS), in aged (20 months) rats. Series of basal RR interval (RRi) and systolic AP (SAP) were studied by autoregressive spectral analysis with oscillations quantified in low (LF: 0.2–0.8 Hz) and high frequency (HF: 0.8–2.5 Hz). BRS was measured by linear regression between HR and MAP changes. Captopril did not affect the spectra of RRi or SAP in young rats. Aged rats presented a reduction in variance (time domain) and in LF and HF oscillations of RRi and SAP. Captopril induced, in aged rats, a decrease in absolute and normalized LF oscillations and in LF/HF ratio of RRi. Captopril also reduced the variance, without changing its LF or HF components of SAP. Reflex tachycardia was reduced in aged as compared to young rats (− 1.1 ± 0.2 versus − 3.4 ± 0.5 bpm/mm Hg) and captopril did not affect it. Reflex bradycardia was also reduced in aged rats (− 0.7 ± 0.5 versus − 2.0 ± 0.4 bpm/mm Hg), but captopril prevented this attenuation in aged rats (− 2.3 ± 0.3 versus − 0.7 ± 0.5 bpm/mm Hg). These data indicate that there is a reduction in HR and SAP variability during aging, suggesting impairment of cardiovascular autonomic control. Captopril was able to change the power of oscillatory components of RRi, suggesting a shift in cardiac sympatho/vagal balance toward parasympathetic predominance. In addition, blockage of ACE improved the reflex bradycardia, but not the reflex tachycardia in aged rats.

Connective Tissue Growth Factor and Cardiac Fibrosis after Myocardial Infarction

The temporal and spatial expression of transforming growth factor (TGF)-beta(1) and connective tissue growth factor (CTGF) was assessed in the left ventricle of a myocardial infarction (MI) model of injury with and without angiotensin-converting enzyme (ACE) inhibition. Coronary artery ligated rats were killed 1, 3, 7, 28, and 180 days after MI. TGF-beta(1), CTGF, and procollagen alpha1(I) mRNA were localized by in situ hybridization, and TGF-beta(1) and CTGF protein levels by immunohistochemistry. Collagen protein was measured using picrosirius red staining. In a separate group, rats were treated for 6 months with an ACE inhibitor. There were temporal and regional differences in the expression of TGF-beta(1), CTGF, and collagen after MI. Procollagen alpha1(I) mRNA expression increased in the border zone and scar peaking 1 week after MI, whereas collagen protein increased in all areas of the heart over the 180 days. Expression of TGF-beta(1) mRNA and protein showed major increases in the border zone and scar peaking 1 week after MI. The major increases in CTGF mRNA and protein occurred in the viable myocardium at 180 days after MI. Long-term ACE inhibition reduced left ventricular mass and decreased fibrosis in the viable myocardium, but had no effect on cardiac TGF-beta(1) or CTGF. TGF-beta(1) is involved in the initial, acute phase of inflammation and repair after MI, whereas CTGF is involved in the ongoing fibrosis of the heart. The antifibrotic benefits of captopril are not mediated through a reduction in CTGF.

Persistent Effects on Blood Pressure and Renal Function of Perindopril Alone or Combined With Losartan in Lyon Hypertensive Rats

In Lyon genetically hypertensive (LH) rats, an early and long-term angiotensin-converting enzyme (ACE) inhibition with perindopril prevents their hypertension and renal alterations. The present work aimed to determine whether: 1) these effects persist after treatment withdrawal; 2) a short-term additional angiotensin II type 1 (AT1) receptor blockade with losartan potentiates these effects; and 3) an early combination of low doses of perindopril and losartan produces the same prolonged effects as monotherapy with a higher dose of perindopril. Perindopril (0.4 or 3 mg/kg/day orally) was given from 3 to 12 weeks of age to male LH rats. In other perindopril-treated LH rats, losartan (10 mg/kg/day orally) was added 1 week before perindopril withdrawal and during a 3-week period. In another group of LH rats, perindopril (0.1 mg/kg/day) and losartan (2.5 mg/kg/day) were given together from 3 to 12 weeks. Systolic blood pressure (SBP) and diastolic blood pressure (DBP) were monitored using radio-telemetry and renal function studied in anesthetized rats. Eight weeks after perindopril withdrawal, a significant reduction (P < .05) in SBP and DBP was observed with the both doses (SBP: 135 +/- 3, 139 +/- 5 v 157 +/- 4; DBP: 89 +/- 4, 93 +/- 5 v 111 +/- 3 mm Hg for 0.4 and 3 mg/kg/day v untreated LH rats). This was accompanied by a persistent decrease in urinary protein excretion and a long-lasting improvement in pressure natriuresis. The persistent antihypertensive effect was not improved by short-term addition of losartan. Interestingly, the early combination of perindopril with losartan at fourfold lower doses produced similar persistent antihypertensive and renoprotective effects. The blood pressure reduction produced by an early ACE inhibition in LH rats persists long after treatment withdrawal and is associated with an improvement in renal function. The combination of low doses of perindopril and losartan reveals a long-term effect similar to that of a monotherapy with a higher dose of perindopril.

Systematic Review of Combined Angiotensin-Converting Enzyme Inhibition and Angiotensin Receptor Blockade in Hypertension

Some evidence suggests that long-term angiotensin-converting enzyme (ACE) inhibition may become less effective, thereby increasing angiotensin II levels, which could be inhibited by the addition of an angiotensin receptor blocker. We conducted a meta-analysis of randomized trials with searches of MEDLINE, EMBASE, and Cochrane databases. Overall, the combination of an ACE inhibitor and an angiotensin receptor blocker reduced ambulatory blood pressure by 4.7/3.0 mm Hg (95% confidence interval [CI], 2.9 to 6.5/1.6 to 4.3) compared with ACE inhibitor monotherapy and 3.8/2.9 mm Hg (2.4 to 5.3/0.4 to 5.4) compared with angiotensin receptor blocker monotherapy. Clinic blood pressure was reduced by 3.8/2.7 mm Hg (0.9 to 6.7/0.8 to 4.6) and 3.7/2.3 mm Hg (0.4 to 6.9/0.2 to 4.4) compared with ACE inhibitor and angiotensin receptor blocker, respectively. However, the majority of these studies used submaximal doses or once-daily dosing of shorter-acting ACE inhibitors and, when a larger dose of shorter-acting ACE inhibitor was given or a longer-acting ACE inhibitor was used, there was generally no additive effect of the angiotensin receptor blocker on blood pressure. Proteinuria was reduced by the combination compared with ACE inhibitor and angiotensin receptor blocker monotherapy, an effect that was independent of blood pressure in several studies, suggesting that the combination could have benefits in proteinuric nephropathies. None of the studies was of sufficient size and duration to determine whether there may be safety concerns. In conclusion, although there is a small additive effect on blood pressure with an ACE inhibitor-angiotensin receptor blocker combination, the routine use of this combination in uncomplicated hypertension is not recommended until more carefully controlled studies are performed.

Bradykinin Contributes to the Systemic Hemodynamic Effects of Chronic Angiotensin-Converting Enzyme Inhibition in Patients With Heart Failure

Bradykinin is an endogenous vasodilator that may contribute to the systemic effects of angiotensin-converting enzyme (ACE) inhibitor therapy. Using B9340, a bradykinin receptor antagonist, we determined the contribution of bradykinin to the systemic hemodynamic effects of long-term ACE inhibition in patients with chronic heart failure. Fourteen patients with heart failure received enalapril (10 mg twice daily) or losartan (50 mg twice daily) in a randomized double-blind crossover trial. After 6 weeks treatment, patients underwent right heart catheterization and were randomized to an intravenous infusion of B9340 (2 to 20 microg/kg per minute) or saline placebo. After B9340 infusion in patients treated with enalapril, mean arterial pressure (+5.2 mm Hg), systemic vascular resistance (+315 dynes x s/cm5), pulmonary arterial wedge pressure (-1.4 mm Hg), and mean pulmonary arterial pressure (-1.3 mm Hg) were greater compared with losartan (P<0.005, P=0.07, P<0.0001, and P<0.05 respectively) or placebo infusion (P< or =0.005 for all). There was a reduction in cardiac output after B9340 with enalapril compared with placebo (P<0.001) but not losartan. Bradykinin contributes to the systemic hemodynamic effects of long-term ACE inhibition in patients with heart failure. This mechanism may explain the apparent clinical differences between ACE inhibitors and angiotensin receptor blockers in the treatment of heart failure.

P2155 Bradykinin mediates systemic vasodilatation associated with long-term angiotensin-converting enzyme inhibition in patients with congestive heart failure

P2155 Bradykinin mediates systemic vasodilatation associated with long-term angiotensin-converting enzyme inhibition in patients with congestive heart failure

Long-term angiotensin-converting enzyme inhibition reduces plasma asymmetric dimethylarginine and improves endothelial nitric oxide bioavailability and coronary microvascular function in patients with syndrome X

Angiotensin-converting enzyme (ACE) inhibition has been shown to improve clinical myocardial ischemia in patients with syndrome X (angina pectoris, positive treadmill exercise test, normal coronary angiograms, and no evidence of coronary spasm). This study was conducted to investigate the effects of long-term ACE inhibitors on endothelial nitric oxide (NO) metabolism and coronary microvascular function in patients with syndrome X. After a 2-week washout period, 20 patients with syndrome X were randomized to receive either enalapril, an ACE inhibitor, 5 mg twice daily (n = 10) or placebo (n = 10) in a double-blind design for 8 weeks. Another 6 age- and gender-matched subjects with negative treadmill exercise tests were also studied as controls. Compared with control subjects, patients with syndrome X had significantly reduced coronary flow reserve, reduced plasma levels of nitrate and nitrite (NOx), and a reduced plasma l-arginine to asymmetric dimethylarginine (ADMA) ratio (an index of systemic NO metabolism), as well as reduced endothelial function. These patients also had increased plasma levels of ADMA, which is an endogenous inhibitor of NO synthase and of von Willebrand factor, a marker of endothelial injury. Baseline characteristics including exercise performance and coronary flow reserve were similar between enalapril and placebo groups. After an 8-week treatment period, exercise duration (p = 0.001) and coronary flow reserve (p = 0.001) significantly improved with enalapril but not with placebo. Enalapril treatment, but not placebo, reduced plasma von Willebrand factor (p = 0.03) and ADMA levels (p = 0.01) and increased NOx levels (p = 0.01) and the ratio of l-arginine to ADMA (p <0.01). In patients with syndrome X, the plasma NOx level was positively and ADMA level inversely correlated with coronary flow reserve before and after the treatment. In conclusion, long-term ACE inhibitor treatment with enalapril improved coronary microvascular function as well as myocardial ischemia in patients with syndrome X. This may be related to the improvement of endothelial NO bioavailability with the reduction of plasma ADMA levels.

Long-term angiotensin-converting enzyme inhibition with ramipril reduces thrombin generation in human hypertension

Long-term angiotensin-converting enzyme inhibition with ramipril reduces thrombin generation in human hypertension

Long-term angiotensin-converting enzyme and angiotensin I–receptor inhibition in pacing-induced heart failure: Effects on myocardial interstitial bradykinin levels

Background: We examined whether and to what degree long-term angiotensin-converting enzyme (ACE) inhibition, angiotensin type 1 (AT1)-receptor blockade, or combined inhibition in developing congestive heart failure (CHF) alter myocardial interstitial bradykinin (BF) levels. Methods and Results: Pigs (27–30 kg) underwent rapid pacing–induced CHF (240 bpm, 3 weeks; n = 10); pacing CHF with concomitant ACE inhibition (benezaprilat, 3.75 mg/day; n = 10); pacing CHF and concomitant AT1-receptor blockade (valsartan, 60 mg/day; n = 10); pacing CHF and combined inhibition (benezaprilat/valsartan, 1.87/60 mg/day, respectively; n = 10); or served as controls (no pacing, no treatment; n = 10). Steady-state myocardial interstitial BK levels were quantitated by microdialysis. Cardiac output decreased to 1.95 ± 0.18 L/min in pacing CHF compared with control (3.78 ± 0.38; P <.05). Cardiac output increased from untreated CHF values with concomitant ACE inhibition (3.91 ± 0.27 L/min), AT1-receptor blockade (3.30 ± 0.41 L/min), or combined ACE/AT1-receptor inhibition (4.13 ± 0.32 L/min; all P <.05 v CHF). With pacing CHF, myocardial interstitial BK levels were reduced by approximately 50% from control values and were normalized in the ACE inhibition and combined inhibition groups. Conclusions: Long-term ACE inhibition increases myocardial interstitial BK levels with CHF; addition of AT1-receptor blockade does not seem to abrogate these effects.