Mechanism of Natriuretic Effect of Oxytocin.

In rats, intramuscular injection of oxytocin (0.25 nmol/100 g body weight) increased sodium excretion from 19±5 to 120±11 µmol/min. A significant correlation (p<0.001) was revealed between renal excretion of oxytocin and sodium ions. Under the action of oxytocin, natriuresis was characterized by diminished reabsorption of fluid in the proximal tubule of the nephron attested by elevated lithium clearance rate and from stimulation of V1a receptors in the cells of thick ascending loop of Henle. Pmp-Tyr(Me)-Phe-Gln-Asn-Cys-Pro-Arg-Gly-NH2, a V1a receptors antagonist, prevented the natriuretic effect of oxytocin.

Chronic treatment with C-type natriuretic peptide impacts differently in the aorta of normotensive and hypertensive rats.

The aim of this study was to determine whether exogenous administration of C-type natriuretic peptide (CNP) induces functional and morphological vascular changes in spontaneously hypertensive rats (SHR) compared with normotensive rats. Male 12-week-old normotensive Wistar and SHR were administered with saline (NaCl 0.9%) or CNP (0.75 µg/h/100 g) for 14 days (subcutaneous micro-osmotic pumps). Systolic blood pressure (SBP) was measured in awake animals and renal parameters were evaluated. After decapitation, the aorta was removed, and vascular morphology, profibrotic markers, and vascular reactivity were measured. In addition, nitric oxide (NO) system and oxidative stress were evaluated. After 14-days of treatment, CNP effectively reduced SBP in SHR without changes in renal function. CNP attenuated vascular remodeling in hypertensive rats, diminishing both profibrotic and pro-inflammatory cytokines. Also, CNP activated the vascular NO system and exerted an antioxidant effect in aortic tissue of both groups, diminishing superoxide production and thiobarbituric acid-reactive substances, and increasing glutathione content. These results show that chronic treatment with CNP attenuates the vascular damage development in a model of essential hypertension, inducing changes in fibrotic, inflammatory, oxidative, and NO pathways that could contribute to beneficial long-term effects on vascular morphology, extracellular matrix composition, and function. The knowledge of these effects of CNP could lead to improved therapeutic strategies to not only control BP but also reduce vascular damage, primarily responsible for the risk of cardiovascular events.

Prognostic Implications of Changes in Amino-Terminal Pro-B-Type Natriuretic Peptide in Acute Decompensated Heart Failure: Insights From ASCEND-HF.

BACKGROUND: Amino-terminal pro-B-type natriuretic peptide (NTproBNP) is closely associated with prognosis in acute decompensated heart failure (ADHF). As a result, there has been great interest measuring it during the course of treatment. The prognostic implications in both short-term and follow-up changes in NTproBNP need further clarification. METHODS: Baseline, 48-72 hour, and 30-day NTproBNP levels were measured in 795 subjects in the ASCEND-HF trial. Multivariable logistic and Cox-proportional hazards models were used to test the association between static, relative, and absolute changes in NTproBNP with outcomes during and after ADHF. RESULTS: The median NTproBNP at baseline was 5773 (2981-11,579) pg/mL; at 48-72 hours was 3036 (1191-6479) pg/mL; and at 30 days was 2914 (1364-6667) pg/mL. Absolute changes in NTproBNP by 48-72 hours were not associated with 30-day heart failure rehospitalization or mortality (P = .065), relative changes in NTproBNP were nominally associated (P = .046). In contrast, both absolute and relative changes in NTproBNP from baseline to 48-72 hours and to 30 days were closely associated with 180-day mortality (P < .02 for all) with increased discrimination compared to the multivariable models with baseline NTproBNP (P <.05 for models with relative and absolute change at both time points). CONCLUSIONS: Although the degree of absolute change in NTproBNP was dependent on baseline levels, both short-term absolute and relative changes in NTproBNP were independently and incrementally associated with long-term clinical outcomes. Changes in NTproBNP levels at 30-days were particularly well associated with long-term clinical outcomes.

A curious finding of skin blebs: A case report.

Mannitol has been the cornerstone of osmotherapy in the treatment of raised intracranial pressure for the past several decades. We discuss here a case of subcutaneous mannitol extravasation, leading to bullous eruptions and swelling in the forearm of a postoperative patient of arteriovenous malformation. We emphasize the importance of careful selection of peripheral intravenous catheter site, especially when infusing hypertonic solutions with propensity for subcutaneous leaks and tissue damage.

Exhaled nitric oxide and mannitol test to predict exercise-induced bronchoconstriction.

BACKGROUND: Exercise-induced bronchoconstriction (EIB) is diagnosed via exercise challenge on a treadmill, but such testing requires complex equipment and sufficient health-care resources. The fraction of exhaled nitric oxide (FeNO) test and mannitol bronchial provocation test (BPT) may serve as a surrogate for exercise testing. METHODS: We compared the diagnostic utilities of the FeNO test and mannitol BPT in predicting EIB in asthmatic children. We retrospectively analyzed data from 60 asthmatic children aged 6-16 years. We compared the exercise BPT results, FeNO levels, and mannitol BPT data. RESULTS: All subjects were divided into exercise-positive (n = 41) or -negative (n = 19) BPT groups. Of the 41 exercise-positive patients, 32 were mannitol BPT positive and nine were mannitol BPT negative. Of the 19 exercise-negative patients, nine and 10, respectively, were mannitol BPT positive and BPT negative. The maximum % forced expiratory volume in 1 s (FEV1 ) decrease after exercise was positively correlated with FeNO (r = 0.556, P < 0.001), and with mannitol response-dose ratio (RDR; r = 0.416, P = 0.001). The receiver operating characteristic (ROC) curve for FeNO to discriminate between asthmatic subjects with and without EIB had an area under the curve (AUC) of 0.771 (95%CI: 0.643-0.870). The discriminatory ROC curve for mannitol RDR had an AUC of 0.763 (95%CI: 0.633-0.864). The AUC of FeNO and mannitol RDR did not differ significantly. CONCLUSIONS: EIB significantly correlated with both FeNO and mannitol BPT data. Given that both methods similarly predicted EIB in asthmatic children, the simpler and safer FeNO test alone may be a clinically useful diagnostic tool.

Rate pressure product and the components of heart rate and systolic blood pressure in hospitalized heart failure patients with preserved ejection fraction: Insights from ASCEND-HF.

BACKGROUND: Heart rate and systolic blood pressure (SBP) are prognostic markers in heart failure (HF) with reduced ejection fraction (HFrEF). Their combination in rate pressure product (RPP) as well as their role in heart failure with preserved ejection fraction (HFpEF) remains unclear. HYPOTHESIS: RPP and its components are associated with HFpEF outcomes. METHODS: We performed an analysis of Acute Study of Clinical Effectiveness of Nesiritide in Subjects With Decompensated Heart Failure (ASCEND-HF; http://www.clinicaltrials.gov NCT00475852), which studied 7141 patients with acute HF. HFpEF was defined as left ventricular ejection fraction ≥40%. Outcomes were assessed by baseline heart rate, SBP, and RPP, as well as the change of these variables using adjusted Cox models. RESULTS: After multivariable adjustment, in-hospital change but not baseline heart rate, SBP, and RPP were associated with 30-day mortality/HF hospitalization (hazard ratio [HR]: 1.17 per 5-bpm heart rate, HR: 1.20 per 10-mm Hg SBP, and HR: 1.02 per 100 bpm × mm Hg RPP; all P < 0.05). Baseline SBP was associated with 180-day mortality (HR: 0.88 per 10-mm Hg, P = 0.028). Though change in RPP was associated with 30-day mortality/HF hospitalization, the RPP baseline variable did not provide additional associative information with regard to outcomes when compared with assessment of baseline heart rate and SBP variables alone. CONCLUSIONS: An increase in heart rate and SBP from baseline to discharge was associated with increased 30-day mortality/HF hospitalization in HFpEF patients with acute exacerbation. These findings suggest value in monitoring the trend of vital signs during HFpEF hospitalization.

Design and evaluation of novel natriuretic peptide derivatives with improved pharmacokinetic and pharmacodynamic properties.

C-type natriuretic peptide (CNP) and its receptor, natriuretic peptide receptor B (NPR-B), are potent positive regulators of endochondral bone growth, making the CNP pathway one of the most promising therapeutic targets for the treatment of growth failure. However, the administration of exogenous CNP is not fully effective, due to its rapid clearance in vivo. Modification of CNP to potentially druggable derivatives may result in increased resistance to proteolytic degradation, longer plasma half-life (T1/2), and better distribution to target tissues. In the present study, we designed and evaluated CNP/ghrelin chimeric peptides as novel CNP derivatives. We have previously reported that the ghrelin C-terminus increases peptide metabolic stability. Therefore, we combined the 17-membered, internal disulfide ring portion of CNP with the C-terminal portion of ghrelin. The resultant peptide displayed improved biokinetics compared to CNP, with increased metabolic stability and longer plasma T1/2. Repeated subcutaneous administration of the chimeric peptide to mice resulted in a significant acceleration in longitudinal growth, whereas CNP(1-22) did not. These results suggest that the ghrelin C-terminus improves the stability of CNP, and the chimeric peptide may be useful as a novel therapeutic agent for growth failure and short stature.

The use of nesiritide in patients with critical cardiac disease.

OBJECTIVE: We evaluated the use of nesiritide in children with critical CHD, pulmonary congestion, and inadequate urine output despite undergoing conventional diuretic therapy. DESIGN: We conducted a retrospective analysis of 11 patients with critical CHD, comprising 18 infusions, each of which occurred during separate hospitalisations. Haemodynamic parameters were assessed, and the stage of acute kidney injury was determined before and throughout the duration of therapy using a standardised definition of acute kidney injury - The Kidney Disease: Improving Global Outcomes criteria. Patients Children with critical CHD, pulmonary congestion, and inadequate urinary output despite undergoing diuretic therapy were included. Measurements and main results The use of nesiritide was associated with a significant decrease in the maximum and minimum heart rate values and with a trend towards a significant decrease in maximum systolic blood pressure and maximum and minimum central venous pressures. Urine output increased but was not significant. Serum creatinine levels decreased significantly during the course of therapy (-0.26 mg/dl [-0.50, 0.0], p=0.02), and the number of patients who experienced a decrease in the stage of acute kidney injury of 2 or more - where a change in the stage of acute kidney disease of 2 or more was possible, that is, baseline stage >1 - was highly significant (five of 12 patients, 42%, p<0.001). CONCLUSIONS: Nesiritide had a favourable impact on haemodynamics, and its use was not associated with deterioration of renal function in patients with critical CHD.

Hospitalization for Recently Diagnosed Versus Worsening Chronic Heart Failure: From the ASCEND-HF Trial.

BACKGROUND: It is unclear how patients hospitalized for acute heart failure (HF) who are long-term chronic HF survivors differ from those with more recent HF diagnoses. OBJECTIVES: The goal of this study was to evaluate the influence of HF chronicity on acute HF patient profiles and outcomes. METHODS: The ASCEND-HF (Acute Study of Clinical Effectiveness of Nesiritide in Decompensated Heart Failure) trial randomized 7,141 hospitalized patients with acute HF with reduced or preserved ejection fraction (EF) to receive nesiritide or placebo in addition to standard care. The present analysis compared patients according to duration of HF diagnosis before index hospitalization by using pre-specified cutoffs (0 to 1 month [i.e., "recently diagnosed"], >1 to 12 months, >12 to 60 months, and >60 months). RESULTS: Overall, 5,741 (80.4%) patients had documentation of duration of HF diagnosis (recently diagnosed, n = 1,536; >1 to 12 months, n = 1,020; >12 to 60 months, n = 1,653; and >60 months, n = 1,532). Across HF duration groups, mean age ranged from 64 to 66 years, and mean ejection fraction ranged from 29% to 32%. Compared with patients with longer HF duration, recently diagnosed patients were more likely to be women with nonischemic HF etiology, higher baseline blood pressure, better baseline renal function, and fewer comorbidities. After adjustment, compared with recently diagnosed patients, patients with longer HF duration were associated with more persistent dyspnea at 24 h (>1 to 12 months, odds ratio [OR]: 1.20; 95% confidence interval [CI]: 0.97 to 1.48; >12 to 60 months, OR: 1.34; 95% CI: 1.11 to 1.62; and >60 months, OR: 1.31; 95% CI: 1.08 to 1.60) and increased 180-day mortality (>1 to 12 months, hazard ratio [HR]: 1.89; 95% CI: 1.35 to 2.65; >12 to 60 months, HR: 1.82; 95% CI: 1.33 to 2.48; and >60 months, HR: 2.02; 95% CI: 1.47 to 2.77). The influence of HF duration on mortality was potentially more pronounced among female patients (interaction p = 0.05), but did not differ according to age, race, prior ischemic heart disease, or ejection fraction (all interactions, p ≥ 0.23). CONCLUSIONS: In this acute HF trial, patient profile differed according to duration of the HF diagnosis. A diagnosis of HF for ≤1 month before hospitalization was independently associated with greater early dyspnea relief and improved post-discharge survival compared to patients with chronic HF diagnoses. The distinction between de novo or recently diagnosed HF and worsening chronic HF should be considered in the design of future acute HF trials. (A Study Testing the Effectiveness of Nesiritide in Patients With Acute Decompensated Heart Failure; NCT00475852).

Effect of sodium nitrite on renal function and sodium and water excretion and brachial and central blood pressure in healthy subjects: a dose-response study.

Sodium nitrite (NaNO2) is converted to nitric oxide (NO) in vivo and has vasodilatory and natriuretic effects. Our aim was to examine the effects of NaNO2 on hemodynamics, sodium excretion, and glomerular filtration rate (GFR). In a single-blinded, placebo-controlled, crossover study, we infused placebo (0.9% NaCl) or 0.58, 1.74, or 3.48 µmol NaNO2·kg-1·h-1 for 2 h in 12 healthy subjects, after 4 days of a standard diet. Subjects were supine and water loaded. We measured brachial and central blood pressure (BP), plasma concentrations of renin, angiotensin II, aldosterone, arginine vasopressin (P-AVP), and plasma nitrite (P-[Formula: see text]), GFR by Cr-EDTA clearance, fractional excretion of sodium (FENa) free water clearance (CH2O), and urinary excretion rate of guanosine 3',5'-cyclic monophosphate (U-cGMP). The highest dose reduced brachial systolic BP (5.6 mmHg, P = 0.003), central systolic BP (5.6 mmHg, P = 0.035), and CH2O (maximum change from 3.79 to 1.27 ml/min, P = 0.031) and increased P-[Formula: see text] (from 0.065 to 0.766 µmol/l, P < 0.001), while reducing U-cGMP (from 444 to 247 pmol/min, P = 0.004). GFR, FENa, P-AVP, and the components in the renin-angiotensin-aldosterone system did not change significantly. In conclusion, intravenous NaNO2 induced a dose-dependent reduction of brachial and central BP. The hemodynamic effect was not mediated by the renin-angiotensin-aldosterone system. NaNO2 infusion resulted in a vasopressin-independent decrease in CH2O and urine output but no change in urinary sodium excretion or GFR. The lack of increase in cGMP accompanying the increase in [Formula: see text] suggests a direct effect of nitrite or nitrate on the renal tubules and vascular bed with little or no systemic conversion to NO.

Induced hypernatraemia is protective in acute lung injury.

BACKGROUND: Sucrose induced hyperosmolarity is lung protective but the safety of administering hyperosmolar sucrose in patients is unknown. Hypertonic saline is commonly used to produce hyperosmolarity aimed at reducing intra cranial pressure in patients with intracranial pathology. Therefore we studied the protective effects of 20% saline in a lipopolysaccharide lung injury rat model. 20% saline was also compared with other commonly used fluids. METHODS: Following lipopolysaccharide-induced acute lung injury, male Sprague Dawley rats received either 20% hypertonic saline, 0.9% saline, 4% albumin, 20% albumin, 5% glucose or 20% albumin with 5% glucose, i.v. During 2h of non-injurious mechanical ventilation parameters of acute lung injury were assessed. RESULTS: Hypertonic saline resulted in hypernatraemia (160 (1) mmol/l, mean (SD)) maintained through 2h of ventilation, and in amelioration of lung oedema, myeloperoxidase, bronchoalveolar cell infiltrate, total soluble protein and inflammatory cytokines, and lung histological injury score, compared with positive control and all other fluids (p ≤ 0.001). Lung physiology was maintained (conserved PaO2, elastance), associated with preservation of alveolar surfactant (p ≤ 0.0001). CONCLUSION: Independent of fluid or sodium load, induced hypernatraemia is lung protective in lipopolysaccharide-induced acute lung injury.

Nesiritide in patients hospitalized for acute heart failure: does timing matter? Implication for future acute heart failure trials.

AIMS: It remains unclear if early administration of i.v. nesiritide in patients hospitalized with acute heart failure (AHF) is associated with improved clinical outcomes. METHODS AND RESULTS: We analysed data from 7007 patients enrolled in ASCEND-HF to examine the associations between time to treatment with study medication (nesiritide or placebo) and clinical endpoints: (i) moderate to marked dyspnoea relief on a 7-point Likert scale at 6 h; (ii) 30-day all-cause mortality or re-hospitalization; and (iii) 30-day all-cause mortality. The median time to study drug administration was 16.7 h (25th, 75th percentiles = 6.5, 23.1), with significant regional variation (e.g. median of 13.0 h in Asia-Pacific vs. 18.4 h in North America). After risk adjustment, each hour delay in study medication after the first 10 h from initial hospital presentation was associated with modestly reduced odds of dyspnoea relief [(adjusted odds ratio (OR) 0.98, 95% confidence interval (CI) 0.98-0.99; P < 0.0001]. Every hour delay in study medication was associated with modestly higher all-cause mortality or re-hospitalization (unadjusted OR 1.01, 95% CI 1.01-1.02; P < 0.001) due to pre-randomization therapies and known predictors of 30-day outcomes (adjusted P = 0.12). There was no significant association between time to study drug and all-cause mortality (P > 0.08). CONCLUSION: In a large international AHF trial, time to treatment with study medication varied markedly across regions. Earlier administration of study medication was associated with modestly better dyspnoea relief, but not 30-day clinical outcomes. The association between timing of treatment with study medication and study endpoints may have implications for the interpretation of AHF studies and future trial design.

Effect of rhBNP on renal function in STEMI-HF patients with mild renal insufficiency undergoing primary PCI.

This study aims to investigate the effect of recombinant human brain natriuretic peptide (rhBNP) on renal function and contrast-induced nephropathy (CIN) incidence in ST-segment elevation myocardial infarction and heart failure (STEMI-HF) patients with mild renal insufficiency undergoing primary percutaneous coronary intervention (PCI). A total of 116 participants were randomized into rhBNP (rhBNP, n = 57) and nitroglycerin group (NIT, n = 59), receiving intravenous rhBNP or nitroglycerin from admission to 72 h after PCI. Renal function was assessed by serum creatinine (SCr), estimated glomerular filtration rate (eGFR), Cystatin-C (Cys-C) and ß2-microglobulin before and after primary PCI, and calculated the incidence of CIN within 72 h after PCI. There were no significant differences in SCr, eGFR and ß2-microglobulin between the two groups (P > 0.05, respectively). Compared with the NIT group, the total urinary volume within 72 h was higher while the level of Cys-C at 24 and 72 h after PCI was lower in the rhBNP group. rhBNP was associated with a decline in the incidence of CIN (12.28 vs. 28.81 %, P < 0.05). No differences were detected in mortality and re-hospitalization in 3 months between the two groups. The incidence of renal injury was not different between rhBNP and nitroglycerin in STEMI-HF patients with mild renal insufficiency. However, infusion of rhBNP was associated with a decline in incidence of CIN.

Predictors of clinical outcomes in acute decompensated heart failure: Acute Study of Clinical Effectiveness of Nesiritide in Decompensated Heart Failure outcome models.

BACKGROUND: Patients hospitalized for acute decompensated heart failure (ADHF) are at high risk for early mortality and rehospitalization. Risk stratification of ADHF using clinically available data on admission is increasingly important to integrate with clinical pathways. Our goal was to create a simple method of screening patients upon admission to identify those with increased risk of future adverse events. METHODS: Using ASCEND-HF, a pragmatic clinical trial conducted in 398 sites globally, we developed and validated logistic regression risk models for (a) 30-day mortality/HF rehospitalization, (b) 30-day mortality/all-cause rehospitalization, (c) 30-day all-cause mortality, and (d) 180-day all-cause mortality. Fifty-one candidate variables were evaluated based on prior publications and clinical review. Final models were selected based on stepwise selection with entry and a staying criterion of P < .01. The 30-day mortality model was externally validated, and coefficients were converted to an additive risk score. RESULTS: Among 7,141 patients, the median age was 67 years, 34% were female, and 80% had a left ventricular ejection fraction <40%. The models had between 5 and 12 risk factors with c-indices ranging from 0.68 to 0.75. A simplified score, including age, systolic blood pressure, sodium, blood urea nitrogen, and dyspnea at rest, discriminated 30-day mortality risk from 0.5% (score 0) to 53% (score 10). CONCLUSIONS: Commonly available clinical variables provide simple risk stratification for clinical outcomes among patients with ADHF, and these models may be considered for integration into routine clinical care.

Loop diuretic dose adjustments after a hospitalization for heart failure: insights from ASCEND-HF.

AIMS: Loop diuretics are a cornerstone of heart failure (HF) treatment, but data regarding diuretic dose adjustments after a HF hospitalization and the association with subsequent outcomes are limited. This study was therefore conducted to determine these factors. METHODS AND RESULTS: We analysed data from 6119 patients enrolled in ASCEND-HF, examining the association between loop diuretic use at the time of discharge, compared with admission, and the composite outcome of 30-day HF re-hospitalization or all-cause mortality. The majority of patients, 3921 (64%), were taking a loop diuretic on admission. At discharge, 3411 (56%) patients were prescribed higher doses compared with admission, including 1867 (31%) initiating daily outpatient diuretics; 1912 (31%) had no dose change and 795 (13%) were prescribed lower doses compared with admission. Initiation of an oral loop diuretic at discharge was independently associated with better 30-day outcomes compared with no dose change [adjusted odds ratio (OR) 0.51, 95% confidence interval (CI) 0.37-0.68]. However, for patients that were already established on a loop diuretic prior to admission, change in the dose at discharge was not associated with improved outcomes compared with no dose change (adjusted OR 0.92, 95% CI 0.79-1.07). CONCLUSIONS: In a large multinational clinical trial, 56% of patients hospitalized with HF were either initiated on a daily loop diuretic at discharge or discharged on higher doses compared with admission. In patients established on diuretics prior to hospitalization, we found no association between changes to chronic doses at discharge and improved outcomes, whereas initiation of loop diuretic therapy was associated with better outcomes compared with no dose change.

Changes in cardiac aldosterone and its synthase in rats with chronic heart failure: an intervention study of long-term treatment with recombinant human brain natriuretic peptide

The physiological mechanisms involved in isoproterenol (ISO)-induced chronic heart failure (CHF) are not fully understood. In this study, we investigated local changes in cardiac aldosterone and its synthase in rats with ISO-induced CHF, and evaluated the effects of treatment with recombinant human brain natriuretic peptide (rhBNP). Sprague-Dawley rats were divided into 4 different groups. Fifty rats received subcutaneous ISO injections to induce CHF and the control group (n=10) received equal volumes of saline. After establishing the rat model, 9 CHF rats received no further treatment, rats in the low-dose group (n=8) received 22.5 μg/kg rhBNP and those in the high-dose group (n=8) received 45 μg/kg rhBNP daily for 1 month. Cardiac function was assessed by echocardiographic and hemodynamic analysis. Collagen volume fraction (CVF) was determined. Plasma and myocardial aldosterone concentrations were determined using radioimmunoassay. Myocardial aldosterone synthase (CYP11B2) was detected by quantitative real-time PCR. Cardiac function was significantly lower in the CHF group than in the control group (P<0.01), whereas CVF, plasma and myocardial aldosterone, and CYP11B2 transcription were significantly higher than in the control group (P<0.05). Low and high doses of rhBNP significantly improved hemodynamics (P<0.01) and cardiac function (P<0.05) and reduced CVF, plasma and myocardial aldosterone, and CYP11B2 transcription (P<0.05). There were no significant differences between the rhBNP dose groups (P>0.05). Elevated cardiac aldosterone and upregulation of aldosterone synthase expression were detected in rats with ISO-induced CHF. Administration of rhBNP improved hemodynamics and ventricular remodeling and reduced myocardial fibrosis, possibly by downregulating CYP11B2 transcription and reducing myocardial aldosterone synthesis.

Changes in cardiac aldosterone and its synthase in rats with chronic heart failure: an intervention study of long-term treatment with recombinant human brain natriuretic peptide.

The physiological mechanisms involved in isoproterenol (ISO)-induced chronic heart failure (CHF) are not fully understood. In this study, we investigated local changes in cardiac aldosterone and its synthase in rats with ISO-induced CHF, and evaluated the effects of treatment with recombinant human brain natriuretic peptide (rhBNP). Sprague-Dawley rats were divided into 4 different groups. Fifty rats received subcutaneous ISO injections to induce CHF and the control group (n=10) received equal volumes of saline. After establishing the rat model, 9 CHF rats received no further treatment, rats in the low-dose group (n=8) received 22.5 µg/kg rhBNP and those in the high-dose group (n=8) received 45 µg/kg rhBNP daily for 1 month. Cardiac function was assessed by echocardiographic and hemodynamic analysis. Collagen volume fraction (CVF) was determined. Plasma and myocardial aldosterone concentrations were determined using radioimmunoassay. Myocardial aldosterone synthase (CYP11B2) was detected by quantitative real-time PCR. Cardiac function was significantly lower in the CHF group than in the control group (P<0.01), whereas CVF, plasma and myocardial aldosterone, and CYP11B2 transcription were significantly higher than in the control group (P<0.05). Low and high doses of rhBNP significantly improved hemodynamics (P<0.01) and cardiac function (P<0.05) and reduced CVF, plasma and myocardial aldosterone, and CYP11B2 transcription (P<0.05). There were no significant differences between the rhBNP dose groups (P>0.05). Elevated cardiac aldosterone and upregulation of aldosterone synthase expression were detected in rats with ISO-induced CHF. Administration of rhBNP improved hemodynamics and ventricular remodeling and reduced myocardial fibrosis, possibly by downregulating CYP11B2 transcription and reducing myocardial aldosterone synthesis.

ROSE-AHF and lessons learned.

Nesiritide and dopamine have been recognized for some time as potential renal adjunct therapies in the management of patients with acute heart failure (AHF). Several studies have yielded conflicting evidence of the efficacy of both medications in enhancing the renal function of patients with AHF. The Renal Optimization Strategies Evaluation (ROSE) study was a multicenter double-blind placebo controlled trial designed to assess the potential renoprotective effects of low-dose nesiritide and dopamine in AHF patients with renal dysfunction. This article will focus on previous research, summary of results, and lessons learned from the ROSE-AHF trial as well as future directions for clinical research and applications.

Low-dose B-type natriuretic peptide raises cardiac sympathetic nerve activity in sheep.

The reported effects of atrial natriuretic peptide (ANP) on sympathetic nerve activity (SNA) are variable, dependent on concomitant hemodynamic actions, and likely to be regionally differentiated. There are few reports of the effect of B-type natriuretic peptide (BNP) on SNA and none have measured cardiac SNA (CSNA) by direct microneurography. We measured the effects of low-dose ANP and BNP (2.4 pmol·kg(-1)·min(-1) infused for 120 min) on CSNA and hemodynamics in conscious sheep (n = 8). While there was a trend for mean arterial pressure and cardiac output to fall with both ANP and BNP, changes were not significant compared with vehicle control. However, BNP did significantly reduce systolic arterial (97 ± 4.2 vs. 107 ± 6.8 mmHg during control; P = 0.043) and pulse pressures (0.047) and increase heart rate (110 ± 6.7 vs. 96 ± 7.3 beats/min; P = 0.044). Trends for these hemodynamic parameters to change with ANP did not achieve statistical significance. ANP also had no significant effect on any CSNA parameters measured. In contrast, BNP induced a rise in both CSNA burst frequency (∼20 bursts/min higher than control, P = 0.011) and burst area (∼40% higher than control, P = 0.013). BNP-induced rises in burst incidence (bursts/100 beats), and burst area per 100 beats, however, were not significant. In conclusion, BNP infused at low doses that only had subtle effects on hemodynamics increased CSNA burst frequency and burst are per minute. This increase in CSNA may in large part be secondary to an increase in heart rate as CSNA burst incidence and burst area per 100 beats were not significantly increased. This study provides no evidence for inhibition of CSNA by natriuretic peptides.