Natriuretic peptides (NP) mediate their effects by activating membrane-bound guanylyl cyclase-coupled receptors A (NPR-A) or B (NPR-B). Whereas the pathophysiological role of NPR-A has been widely studied, only limited knowledge on the cardiovascular function of NPR-B is available. In vitro studies suggest antiproliferative and antihypertrophic actions of the NPR-B ligand C-type NP (CNP). Because of the lack of a specific pharmacological inhibitor, these effects could not clearly be attributed to impaired NPR-B signaling. Recently, gene deletion revealed a predominant role of NPR-B in endochondral ossification and development of female reproductive organs. However, morphological abnormalities and premature death of NPR-B-deficient mice preclude detailed cardiovascular phenotyping. In the present study, a dominant-negative mutant (NPR-B⌬KC) was used to characterize CNP-dependent NPR-B signaling in vitro and in transgenic rats. Here we demonstrate that reduced CNP-but not atrial NP-dependent cGMP response attenuates antihypertrophic potency of CNP in vitro. In transgenic rats, NPR-B⌬KC expression selectively reduced NPR-B but not NPR-A signaling. NPR-B⌬KC transgenic rats display progressive, blood pressure-independent cardiac hypertrophy and elevated heart rate. The hypertrophic phenotype is further enhanced in chronic volume overload-induced congestive heart failure. Thus, this study provides evidence linking NPR-B signaling to the control of cardiac growth.C-type natriuretic peptide ͉ knockdown

Natriuretic peptide (NP) deficiency and sustained renin-angiotensin system activation are associated with impaired oxidative metabolism and predispose to type-2 diabetes. We hypothesized that sacubitril/valsartan (LCZ696), which augments NP through neprilysin inhibition while blocking angiotensin II type-1 (AT )-receptors, improves insulin sensitivity, lipid mobilization, and oxidation. After 8 weeks of treatment of obese patients with hypertension, sacubitril/valsartan 400 mg q.d., but not amlodipine 10 mg q.d., was associated with a significant increase from baseline in the insulin sensitivity index (hyperinsulinemic-euglycemic clamp), and tended to be higher in patients treated with sacubitril/valsartan compared to amlodipine. Abdominal adipose tissue interstitial glycerol concentrations increased with sacubitril/valsartan, but decreased with amlodipine. Whole-body lipolysis and substrate oxidation did not change with either treatment. Results confirm that sacubitril/valsartan treatment leads to a metabolic benefit in the study population and supports the relevance of neprilysin inhibition along with AT -receptor blockade in the regulation of human glucose and lipid metabolism.

Atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) are cardiac hormones that are involved in water and electrolyte homeostasis in heart failure. Although both hormones exert almost identical biological actions, the differential regulation of cardiac ANP and BNP mRNA in compensated and overt heart failure is not known. To study the hypothesis that cardiac BNP is more specifically induced in overt heart failure, a large aortocaval shunt of 30 days duration was produced in rats and compared with compensated heart failure. Compensated heart failure was induced either by a small shunt of 30 days duration or by a large shunt of 3 days duration. Both heart failure models were characterized by increased cardiac weight, which was significantly higher in the large-shunt model, and central venous pressure. Left ventricular end-diastolic pressure was elevated only in the overt heart failure group (control: 5.7 +/- 0. 7; small shunt: 8.6 +/- 0.9; large shunt 3 days: 8.5 +/- 1.7; large shunt 30 days: 15.9 +/- 2.6 mmHg; P < 0.01). ANP and BNP plasma concentrations were elevated in both heart failure models. In compensated heart failure, ANP mRNA expression was induced in both ventricles. In contrast, ventricular BNP mRNA expression was not upregulated in any of the compensated heart failure models, whereas it increased in overt heart failure (left ventricle: 359 +/- 104% of control, P < 0.001; right ventricle: 237 +/- 33%, P < 0.01). A similar pattern of mRNA regulation was observed in the atria. These data indicate that, in contrast to ANP, cardiac BNP mRNA expression might be induced specifically in overt heart failure, pointing toward the possible role of BNP as a marker of the transition from compensated to overt heart failure.

Since LV mass change correlates with cardiovascular prognosis, the greater reductions in LV mass indicate valuable advantages of sacubitril/valsartan compared to olmesartan. The finding that LV mass index decrease might be to some extent independent of SBP suggests that the effect of the dual-acting agent may go beyond those due to its BP-lowering ability.

S alt-sensitive hypertension (SSH) is characterized by an increase in blood pressure (BP) in response to sodium load and is associated with an increased risk of cardiovascular events. [1][2][3] Owing to high dietary salt intake and genetic predisposition, salt sensitivity of BP is of particular clinical relevance in Asian populations. [4][5][6][7][8] Considering its pathophysiology, thiazide-type diuretics are the preferred antihypertensive agents for patients with SSH.9-11 However, conditions such as hyponatremia and hypokalemia caused by thiazide-type diuretics often contribute to morbidity and mortality, if left unrecognized. Hence, antihypertensive agents that improve urinary sodium excretion without altering electrolyte concentrations would be a better therapeutic option for patients with SSH. Among multiple pathophysiological mechanisms, a relative deficiency of atrial natriuretic peptide (ANP) is considered to result in sodium retention and a suboptimal vasodilatory response to sodium loading observed in patients with SSH.12-15 The renin-angiotensin-aldosterone system (RAAS) also plays a role in the pathogenesis of SSH by modulating renal sodium reabsorption.16 Therefore, enhancing the activity of natriuretic peptides along with inhibition of the RAAS may be an effective, Abstract-Salt-sensitive hypertension (SSH) is characterized by impaired sodium excretion and subnormal vasodilatory response to salt loading. Sacubitril/valsartan (LCZ696) was hypothesized to increase natriuresis and diuresis and result in superior blood pressure control compared with valsartan in Asian patients with SSH. In this randomized, doubleblind, crossover study, 72 patients with SSH received sacubitril/valsartan 400 mg and valsartan 320 mg once daily for 4 weeks each. SSH was diagnosed if the mean arterial pressure increased by ≥10% when patients switched from low (50 mmol/d) to high (320 mmol/d) sodium diet. The primary outcome was cumulative 6-and 24-hour sodium excretion after first dose administration. Compared with valsartan, sacubitril/valsartan was associated with a significant increase in natriuresis (adjusted treatment difference: 24.5 mmol/6 hours, 50.3 mmol/24 hours, both P<0.001) and diuresis (adjusted treatment difference: 291.2 mL/6 hours, P<0.001; 356.4 mL/24 hours, P=0.002) on day 1, but not on day 28, and greater reductions in office and ambulatory blood pressure on day 28. Despite morning dosing of both drugs, ambulatory blood pressure reductions were more pronounced at nighttime than at daytime or the 24-hour average. Compared with valsartan, sacubitril/valsartan significantly reduced N-terminal pro B-type natriuretic peptide levels on day 28 (adjusted treatment difference: −20%; P=0.001). Sacubitril/valsartan and valsartan were safe and well tolerated with no significant changes in body weight or serum sodium and potassium levels with either treatments. In conclusion, sacubitril/valsartan compared with valsartan was associated with short-term increases in natriuresis and diuresis, superior office and ambulato...

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AimsLCZ696 (angiotensin receptor neprilysin inhibitor) is a novel drug developed for the treatment of heart failure with reduced ejection fraction. Neprilysin is one of multiple enzymes degrading amyloid‐β (Aβ). Its inhibition may increase Aβ levels. The potential exists that treatment of LCZ696, through the inhibition of neprilysin by LBQ657 (an LCZ696 metabolite), may result in accumulation of Aβ. The aim of this study was to assess the blood–brain‐barrier penetration of LBQ657 and the potential effects of LCZ696 on cerebrospinal fluid (CSF) concentrations of Aβ isoforms in healthy human volunteers.MethodsIn a double‐blind, randomized, parallel group, placebo‐controlled study, healthy subjects received once daily LCZ696 (400 mg, n = 21) or placebo (n = 22) for 14 days.ResultsLCZ696 had no significant effect on CSF AUEC(0,36 h) of the aggregable Aβ species 1–42 or 1–40 compared with placebo (estimated treatment ratios 0.98 [95% CI 0.73, 1.34; P = 0.919] and 1.05 [95% CI 0.82, 1.34; P = 0.702], respectively). A 42% increase in CSF AUEC(0,36 h) of soluble Aβ 1–38 was observed (estimated treatment ratio 1.42 [95% CI 1.05, 1.91; P = 0.023]). CSF levels of LBQ657 and CSF Aβ 1–42, 1–40, and 1–38 concentrations were not related (r 2 values 0.022, 0.010, and 0.008, respectively).ConclusionsLCZ696 did not cause changes in CSF levels of aggregable Aβ isoforms (1–42 and 1–40) compared with placebo, despite achieving CSF concentrations of LBQ657 sufficient to inhibit neprilysin. The clinical relevance of the increase in soluble CSF Aβ 1–38 is currently unknown.

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