The effects of amlodipine and enalapril on renal function in adults with hypertension and nondiabetic nephropathies: a 3-year, randomized, multicenter, double-blind, placebo-controlled study.

BACKGROUND: Placebo-controlled trials have found that angiotensin-converting enzyme inhibitors (ACEIs) decrease proteinuria and slow the progression of nondiabetic nephropathies. However, head-to-head comparisons of ACEIs and calcium channel blockers (CCBs) have shown conflicting results. Indeed, a recent metaanalysis concluded that there is still uncertainty about the greater renoprotection seen with ACEIs or angiotensin II receptor blockers in nondiabetic patients with renal disease, particularly when using true glomerular filtration rate (GFR) as the primary outcome. OBJECTIVE: The objective of this 3-year, randomized, multicenter, double-blind, placebo-controlled study was to compare true GFR decline (measured by yearly 51Cr-EDTA blood clearance) in nondiabetic, nonnephrotic adult hypertensive patients with estimated creatinine clearance of 20 to 60 mL/min.1.73 m(2), when randomized to a CCB (amlodipine, 5-10 mg/d) or an ACEI (enalapril, 5-20 mg/d). METHODS: Patients (aged 18-80 years) entered a 4-week placebo run-in washout period and previous antihypertensive drugs were tapered off over 2 weeks. Add-on treatments were atenolol (50-100 mg/d), loop diuretics (furosemide, 20-500 mg/d or torsemide, 5-200 mg/d), alpha-blockers (prazosin, 2.5-5 mg/d or doxazosin, 1-16 mg/d), and centrally acting drugs (rilmenidine, 1-2 mg/d or methyldopa, 250-500 mg/d). The primary end point was true GFR measured by yearly (51)Cr-EDTA blood clearance. Secondary end points included a clinical composite of renal events and tolerability collected by a full clinical and laboratory evaluation at each study visit. Post hoc analyses for the change in GFR, proteinuria, and time to clinical events were also planned on baseline proteinuria subgroups (<1 and >or=1 g/d) before unblinding the database. RESULTS: Three hundred eighteen patients entered the run-in period and 263 patients (156 men/107 women; mean age, 58 years) were randomized to receive either amlodipine (5 mg/d, n=132) or enalapril (5 mg/d, n=131). Blood pressure declined from 165/102 mm Hg to 138/84 mm Hg and 138/85 mm Hg with amlodipine and enalapril, respectively (no between-group significance). Only 20.8% of the patients randomized to ACEI treatment received diuretics at the last observation. No statistically significant difference was found between amlodipine and enalapril in GFR decline (-4.92 and -3.98 mL/min.1.73 m(2), respectively, at last observation) and composite secondary end point after a median follow-up of 2.9 years, including in the subgroup of patients with proteinuria >1 g/d at baseline. Protein excretion rate decreased significantly from baseline in patients taking enalapril plus diuretics (median -270 mg/d; P<0.001) but not in patients taking amlodipine plus diuretics (-25 mg/d at last observation). CONCLUSION: In this cohort of nondiabetic, nonnephrotic hypertensive patients, no statistically significant difference in true GFR decline was found over 3 years between amlodipine-treated patients and enalapril-treated patients with main add-on treatment with ss-blockers, including in the subgroup of patients with proteinuria >1 g/d.

Nuclear factor-kappaB signaling contributes to severe, but not moderate, angiotensin II-induced left ventricular remodeling.

OBJECTIVE: The transcription factor nuclear factor-kappaB (NF-kappaB) has been implicated in cardiomyocyte hypertrophy in vitro as well as in vivo; however, it is unknown if activation of NF-kappaB plays a mandatory role in the hypertrophic process. Here we characterize the importance of NF-kappaB signaling in moderate and severe left ventricular (LV) hypertrophy in rats with chronic pressure overload induced by angiotensin II (Ang II) infusion. METHODS AND RESULTS: Electrophoretic mobility shift assay analysis revealed that Ang II infusion (2.5 microg/kg per min) for 6 days increased LV NF-kappaB/DNA-binding activity in a biphasic manner in Sprague-Dawley rats. Pyrrolidine dithiocarbamate (PDTC) (100 mg/kg per day), an NF-kappaB inhibitor, abolished Ang II-induced NF-kappaB activation and concomitant increase in tumor necrosis factor-alpha gene expression, while activator protein-1/DNA binding was not affected. Inhibition of NF-kappaB signaling for 6 days significantly attenuated Ang II-induced increases in LV/body weight ratio, LV mean wall thickness and cardiomyocyte cross-sectional area, without compromising LV systolic function. Moreover, PDTC abolished Ang II-induced cardiomyocyte apoptosis and interstitial fibrosis, and attenuated the gene expression of type I collagen. In contrast, a moderate LV hypertrophy induced by Ang II at a lower dose (0.5 microg/kg per min) was not associated with a significant activation of NF-kappaB, and PDTC treatment had no effect on the hypertrophic indices. CONCLUSION: Our in-vivo data indicate a critical role of NF-kappaB signaling in the advanced stage of the remodeling process, whereas development of moderate LV hypertrophy is not dependent on NF-kappaB activation.

Involvement of endogenous ouabain-like compound in the cardiac hypertrophic process in vivo.

The Na(+)/K(+)-ATPase inhibitor ouabain has been shown to trigger hypertrophic growth of cultured cardiomyocytes; however, the significance of endogenous ouabain-like compound (OLC) in the hypertrophic process in vivo is unknown. Here we characterized the involvement of OLC in left ventricular (LV) hypertrophy induced by norepinephrine (NE) and angiotensin II (Ang II) infusions in rats. Administration of NE (300 microg/kg/h) via subcutanously implanted osmotic minipumps for 72 h resulted in a significant increase in left ventricular weight to body weight (LVW/BW) ratio (P<0.001) and a substantial up-regulation of atrial natriuretic peptide (ANP) gene expression (13.2-fold, P<0.001). NE infusion induced a transient increase in plasma OLC levels at 12 h (P<0.05), which returned to control levels by 72 h. Adrenalectomy markedly reduced both basal and NE-induced increase in plasma OLC levels. LVW/BW ratio was not modulated by adrenalectomy; however, ANP gene expression was blunted by 44% (P<0.01) and 47% (P<0.05) at 12 and 72 h, respectively. In agreement, adrenalectomy reduced up-regulation of ANP without affecting LV mass in rats infused with Ang II (33 microg/kg/h). Administration of exogenous ouabain (1 nM to 100 microM) for 24 h had no effect on ANP gene expression in cultured neonatal rat ventricular myocytes. However, the up-regulation of ANP mRNA levels induced by the alpha-adrenergic agonist phenylephrine (1 microM) was markedly enhanced by ouabain (100 microM) (5.6-fold vs. 9.6-fold, P<0.01). These data show that OLC as an adrenal-derived factor may be required for the induction LV ANP gene expression during the hypertrophic process.

Distinct modulation of angiotensin II-induced early left ventricular hypertrophic gene programming by dietary fat type.

Long-term dietary fatty acid intake alters the development of left ventricular hypertrophy, but the linking signaling pathways are unclear. We studied the role and underlying signaling mechanisms of dietary fat intake in the early phase of the hypertrophic process. Rats assigned for 4 weeks of high-oil, high-fat, or standard diet were subjected to angiotensin II (Ang II; 33 microg/kg/h, subcutaneous) or vehicle infusion for 24 h. The Ang II-induced increase in left ventricular mRNA levels of hypertrophy-associated genes was higher in rats fed the high-oil diet compared with the standard diet. Western blotting revealed that, in parallel with changes in gene expression, the high-oil diet increased c-Jun N-terminal kinase phosphorylation (P < 0.001). Ang II increased p38 mitogen-activated protein kinase (MAPK) phosphorylation in rats fed the high-fat diet (3-fold; P < 0.01). The increase in transcription factor activator protein-1 (AP-1) DNA binding activity in response to Ang II was higher in rats fed the high-oil diet compared with those fed the standard diet (P < 0.001). Ang II downregulated inducible nitric oxide synthase mRNA levels in fatty acid-supplemented groups compared with the standard diet group. These results show that dietary fat type modulates the early activation of hypertrophic genes in pressure-overloaded myocardium involving the distinct activation of AP-1 and MAPK signal transduction pathways.

Evidence for a functional role of angiotensin II type 2 receptor in the cardiac hypertrophic process in vivo in the rat heart.

BACKGROUND: The precise function of angiotensin II type 2 receptor (AT2-R) in the mammalian heart in vivo is unknown. Here, we investigated the role of AT2-R in cardiac pressure overload. METHODS AND RESULTS: Rats were infused with vehicle, angiotensin II (Ang II), PD123319 (an AT2-R antagonist), or the combination of Ang II and PD123319 via subcutaneously implanted osmotic minipumps for 12 or 72 hours. Ang II-induced increases in mean arterial pressure, left ventricular weight/body weight ratio, and elevation of skeletal alpha-actin and beta-myosin heavy chain mRNA levels were not altered by PD123319. In contrast, AT2-R blockade resulted in a marked increase in the gene expression of c-fos, endothelin-1, and insulin-like growth factor-1 in Ang II-induced hypertension. In parallel, Ang II-stimulated mRNA and protein expression of atrial natriuretic peptide were significantly augmented by AT2-R blockade. Moreover, PD123319 markedly increased the synthesis of B-type natriuretic peptide. Furthermore, the expression of vascular endothelial growth factor and fibroblast growth factor-1 was downregulated by Ang II only in the presence of AT2-R blockade. CONCLUSIONS: Our results provide evidence that AT2-R plays a functional role in the cardiac hypertrophic process in vivo by selectively regulating the expression of growth-promoting and growth-inhibiting factors.

Circulating and cardiac levels of apelin, the novel ligand of the orphan receptor APJ, in patients with heart failure.

The orphan receptor APJ and its recently identified endogenous ligand, apelin, are expressed in the heart. However, their importance in the human cardiovascular system is not known. This study shows that apelin-like immunoreactivity is abundantly present in healthy human heart and plasma. Gel filtration HPLC analysis revealed that atrial and plasma levels of high molecular weight apelin, possibly proapelin, were markedly higher than those of mature apelin-36 itself. As assessed by quantitative RT-PCR analysis, left ventricular apelin mRNA levels were increased 4.7-fold in chronic heart failure (CHF) due to coronary heart disease (p<0.01) and 3.3-fold due to idiopathic dilated cardiomyopathy (p<0.05), whereas atrial apelin mRNA levels were unchanged. Atrial and plasma apelin-like immunoreactivity as well as atrial and ventricular APJ receptor mRNA levels were significantly decreased in CHF. Our results suggest that a new cardiac regulatory peptide, apelin, and APJ receptor may contribute to the pathophysiology of human CHF.

Endothelin-1 contributes to the Frank-Starling response in hypertrophic rat hearts.

Endothelin-1 is involved in mechanical load-induced cardiac growth processes; it also has effects on contractility. The interaction of endothelin-1 and the Frank-Starling response is unknown. The present study aimed to characterize the role of endothelin-1 in the regulation of the Frank-Starling response, one of the major mechanisms regulating cardiac contractile force, in both normal and hypertrophied hearts. Nontransgenic rat hearts and hypertrophic hearts of hypertensive double transgenic rats harboring human angiotensinogen and renin genes were studied in a Langendorff isolated heart setup with a liquid-filled balloon inside the left ventricle used to measure contractile parameters. The rats were studied at compensated phase, before showing any signs of heart failure. Compensated hypertrophy in double transgenic rat hearts resulted in improved contractility at a given level of preload when compared with nontransgenic rat hearts. Hearts of both rat lines showed preserved Frank-Starling responses, that is, increased contractile function in response to increased end-diastolic pressure. The mixed endothelin A/B receptor antagonist bosentan attenuated the Frank-Starling response by 53% (P<0.01) in the double transgenic hearts but not in nontransgenic hearts. The diastolic parameters remained unaffected. The left ventricles of the double transgenic rat hearts showed an 82% higher level of endothelin type A receptor mRNA and a 25% higher level of immunoreactive endothelin-1 compared with nontransgenic rat hearts. The type 1 angiotensin II receptor antagonist CV-11974 had no significant effect on contractile function in response to load in either strain. These results show that endogenous endothelin-1 contributes to the Frank-Starling response in hypertrophied rat hearts by affecting systolic performance.