Physiology of natriuretic peptides: The volume overload hypothesis revisited

Association of Angiotensin Receptor-Neprilysin Inhibitors Use and Better Cardiorenal Outcomes in Patients With Heart Failure and Acute Kidney Disease

PURPOSE

Angiotensin receptor-neprilysin inhibitors (ARNi) have been shown to improve cardiovascular outcomes in heart failure (HF) patients. However, their impact on HF patients with concurrent acute kidney disease (AKD) remains underexplored. This study investigated the outcomes of ARNi compared to angiotensin-converting enzyme inhibitors (ACEi) in HF patients with AKD.

METHODS

The study included 20,009 hospitalized HF and AKD patients who underwent dialysis during hospitalization, recovered from dialysis within 90 days after discharge, and were followed until November 30, 2022, using data from TriNetX. The study period began in July 2015, coinciding with the availability of ARNi in the market. Propensity score matching (1:1) was applied to balance ARNi and ACEi groups. Adjusted hazard ratios (aHR) with 95% confidence intervals (CI) were calculated to assess the risks of mortality, major adverse kidney events (MAKE), readmission and major adverse cardiac events (MACE). The follow-up period was conducted with a maximum duration of 5 years.

RESULTS

A total of 20,009 AKD patients (mean [SD] age, 59.1 [12.2] years) were enrolled, of whom 21.9% received ARNi, with a median follow-up of 2.3 years. After matching, 4391 patients (mean age, 58.6 years; male, 67.9%) were identified in both the ARNi and control groups. ARNi users exhibited a significantly lower risk of mortality (aHR, 0.32, 95% CI 0.13-0.80, p = 0.01), MAKE (aHR, 0.58, 95% CI 0.51-0.66, p < 0.01 ), and readmission (aHR, 0.61, 95% CI 0.55-0.68, p <0.01) versus controls. However, no significant difference in the risk of MACE was observed between the two groups (aHR, 0.94, 95% CI 0.82-1.09, p = 0.78). Subgroup analysis revealed ARNi users, when concomitantly treated with mineralocorticoids, diuretics, or beta-blockers had significantly lower risks of mortality, readmission, and MAKE than the control group. In addition, ARNi significantly reduced mortality and MAKE in patients with GFR 30-60 mL/min/1.73 m2, irrespective of proteinuria status. However, no significant benefit was observed in patients with GFR <30 mL/min/1.73 m2.

CONCLUSIONS

In HF patients with AKD, ARNi was associated with reduced all-cause mortality, MAKE, and readmission risks compared to ACEi, particularly with concurrent mineralocorticoids, diuretics, or beta-blockers. Future research is necessary to further investigate the impact of ARNi on outcomes in patients with HF and AKD.

The clinical outcomes of dapagliflozin in patients with acute heart failure: A randomized controlled trial (DAPA-RESPONSE-AHF)

AIMS

Dapagliflozin may confer additional decongestive and natriuretic benefits to patients with acute heart failure (AHF). Nonetheless, this hypothesis was not clinically examined. This study aimed primarily to investigate the effect of dapagliflozin on symptomatic relief in those patients.

METHODS

This was a randomized, double-blind study that included 87 patients with AHF presenting with dyspnea. Within 24 h of admission, patients were randomized to receive either dapagliflozin (10 mg/day, N = 45) or placebo (N = 42) for 30 days. The primary outcome was the difference between the two groups in the area under the curve (AUC) of visual analogue scale (VAS) dyspnea score over the first 4 days. Secondary endpoints included urinary sodium (Na) after 2 h of randomization, percent change in NT-proBNP, cumulative urine output (UOP), and differences in mortality and hospital readmission rates.

RESULTS

The results showed that dapagliflozin significantly reduced the AUC of VAS dyspnea score compared to placebo (3192.2 ± 1631.9 mm × h vs 4713.1 ± 1714.9 mm × h, P < 0.001). The relative change of NT-proBNP compared to its baseline was also larger with dapagliflozin (-34.89% vs -10.085%, P = 0.001). Additionally, higher cumulative UOP was found at day 4 (18600 ml in dapagliflozin vs 13700 in placebo, P = 0.031). Dapagliflozin decreased rehospitalization rates within 30 days after discharge, while it did not affect the spot urinary Na concentration, incidence of worsening of heart failure, or mortality rates.

CONCLUSION

Dapagliflozin may provide symptomatic relief and improve diuresis in patients with AHF. Further studies are needed to confirm these findings. https://clinicaltrials.gov/study/NCT05406505.

Association Between Changes in Bioelectrical Impedance Analysis (BIA) Parameter and the Clinical Outcomes in Patients With Acute Heart Failure

BACKGROUND

Volume overload is associated not only with clinical manifestations but also with poor outcomes of heart failure (HF). However, there is an unmet need for effective methods for serial monitoring of volume status during HF hospitalization. The aim of this study was to evaluate the prognostic implication of serial measurement of bioelectrical impedance analysis (BIA) in patients hospitalized with acute HF.

METHODS

This study is a retrospective observational study and screened 310 patients hospitalized due to acute decompensated HF between November 2021 and September 2022. Among them, 116 patients with acute HF who underwent BIA at the time of admission and at discharge were evaluated. We investigated the correlation between change of BIA parameters and the primary composite outcome (in-hospital mortality or rehospitalization for worsening HF within one month).

RESULTS

The median (interquartile range) age was 77 years (67-82 years). The mean left ventricular ejection fraction was 40.7 ± 14.6% and 55.8% of HF patients have HF with reduced ejection fraction. The body water composition (intracellular water [ICW], extracellular water [ECW], and total body water [TBW]) showed a statistically significant correlation with body mass index and LV chamber sizes. Furthermore, the ratio of ECW to TBW (ECW/TBW), as an edema index showed a significant correlation with natriuretic peptide levels. Notably, the change of the edema index during hospitalization (ΔECW/TBW) showed a significant correlation with the primary outcome. The area under the curve of ΔECW/TBW for predicting primary outcome was 0.71 (95% confidence interval [CI], 0.61-0.79; P = 0.006). When patients were divided into two groups based on the median value of ΔECW/TBW, the group of high and positive ΔECW/TBW (+0.3% to +5.1%) had a significantly higher risk of the primary outcome (23.2% vs. 8.3%, adjusted odds ratio, 4.8; 95% CI, 1.2-19.3; P = 0.029) than those with a low and negative ΔECW/TBW (-5.3% to +0.2%).

CONCLUSION

BIA is a noninvasive and effective method to evaluate the volume status during the hospitalization of HF patients. The high and positive value of ΔECW/TBW during hospitalization was associated with poor outcomes in patients with HF.

Comparison of Efficacy and Safety of Angiotensin Receptor-Neprilysin Inhibitors in Patients With Heart Failure With Reduced Ejection Fraction: A Meta-Analysis

The present meta-analysis was conducted to compare the safety and efficacy of angiontensin receptor neprilysin inhibitor (ARNI) with angiotensin receptor blockers (ARBs) and angiotensin-converting-enzyme inhibitors (ACEi) in patients with heart failure with reduced ejection fraction (HFrEF). This meta-analysis was conducted and reported in accordance with the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) statement. Two authors carried out a scientific literature search on online databases, including EMBASE, PubMed, and the Cochrane Library. The following keywords or corresponding Medical Subject Headings (MeSH) were used for the search of relevant articles: "heart failure with reduced ejection fraction," "angiotensin receptor-neprilysin inhibitor," "Angiotensin receptor blockers," and "clinical outcomes." Outcomes assessed in the present meta-analysis included changes in ejection fraction (EF) from baseline in percentage. Other outcomes assessed in the present meta-analysis included all-cause mortality, cardiovascular death, and hospitalization due to heart failure. Adverse events assessed in the present meta-analysis included hypokalemia, acute kidney injury, and hypotension. Total 10 studies were included. This meta-analysis showed that treatment with ARNI was associated with a significantly lower risk of all-cause mortality and cardiovascular death compared to control groups. There was no significant difference between the two groups in terms of change of EF from baseline or hospitalization related to heart failure. However, the risk of hypotension was significantly higher in patients receiving ARNI. The study findings support the use of ARNI as first-line therapy for heart failure with reduced ejection fraction. Further studies are required to determine the optimal use of ARNI in heart failure management and to investigate the mechanisms underlying the increased risk of hypotension.

Network Meta-Analysis Comparing Angiotensin Receptor-Neprilysin Inhibitors, Angiotensin Receptor Blockers, and Angiotensin-Converting Enzyme Inhibitors in Heart Failure With Reduced Ejection Fraction

The superiority of angiotensin receptor-neprilysin inhibitor (ARNI) over angiotensin-converting enzyme inhibitor (ACE-I) and angiotensin receptor blocker (ARB) has not been reassessed after the publication of recent trials that did not find clinical benefits. Therefore, we performed an updated network meta-analysis comparing the efficacy and safety of ARNI, ACE-I, ARB, and placebo in heart failure with reduced ejection fraction. We included randomized clinical trials that compared ARNI, ARB, ACE-I, and placebo in heart failure with reduced ejection fraction. We extracted prespecified efficacy end points and produced network estimates, p scores, and surface under the cumulative ranking curve scores using frequentist and Bayesian network meta-analysis approaches. A total of 28 randomized controlled trials including 47,407 patients were included. ARNI was associated with lower risk of all-cause mortality (relative risk [RR] 0.81, 95% confidence interval [CI] 0.68 to 0.96), cardiac death (RR 0.79, 95% CI 0.64 to 0.99), and major adverse cardiac events (MACEs; RR 0.83, 95% CI 0.72 to 0.97) but higher risk of hypotension (RR 1.46, 95% CI 1.02 to 2.10) than ARB. ARNI was associated with lower risk of MACE (RR 0.85, 95% CI 0.74 to 0.97), but higher risk of hypotension (RR 1.69, 95% CI 1.27 to 2.24) compared with ACE-I. P scores and surface under the cumulative ranking curve scores demonstrated superiority of ARNI over ARB and ACE-I in all-cause mortality, cardiac death, MACE, and hospitalization for heart failure. In conclusion, ARNI was associated with improved clinical outcomes, except for higher risk of hypotension, compared with ARB and ACE-I.

Comparison of ANP and BNP Granular Density in Atria of Rats After Physiological and Pathological Hypertrophy

Atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) are cardiac hormones located in atria granules. Both peptides respond to cardiac pressure and volume dynamics and accordingly serve as translation biomarkers for the clinical treatment of heart failure. Serum ANP and BNP play central secretary roles in blood pressure and cardiac output regulation and have proven utility as differential biomarkers of cardiovascular proficiency and drug-induced maladaptation, yet both peptides are impervious to exercise-induced hypertrophy. We employed immunoelectron microscopy to examine the effects of 28 days of chronic swim exercise or administration of a PPARγ agonist on atrial granules and their stored natriuretic peptides in Sprague Dawley rats. Chronic swimming and drug treatment both resulted in a 15% increase in heart weight compared with controls, with no treatment effects on perinuclear granule area in the left atria (LAs). Drug treatment resulted in larger size granules with greater BNP density in the right atria. Comparing swimming and PPARγ agonist treatment effects on ANP:BNP granule density ratios between atrial chambers revealed a shift toward a greater proportion of ANP than BNP in LAs of swim-trained rats. These data suggest a distinction in the population of ANP and BNP after chronic swim or PPARγ that makes it a novel metric for the differentiation of pathological and physiological hypertrophy.

Therapeutic role of atrial natriuretic peptide in early treatment of traumatic hemorrhagic shock

The biological effect of atrial natriuretic peptide (ANP) in traumatic hemorrhagic shock (THS) is unknown. This study was to evaluate whether ANP therapy can show organ protection in THS. Thirty male Sprague-Dawley rats were divided into three groups: ANP group, sham group, and control group. Pressure-controlled THS was induced in rats in ANP group and control group. ANP at a rate of 0.025 μg/kg/min was infused in ANP group during near-80 min of shock. After that, animals were resuscitated for 60 min and observed until 24 h. Hemodynamic parameters during shock and resuscitation were measured. Serum levels of ANP and lactate dehydrogenase, tissue oxidative stress and inflammatory factors, as well as liver and kidney function were determined. Tissue apoptosis was also assessed. There was no statistically significant difference between ANP group and control group in arterial pressure throughout the 150 min monitoring period. Blood urea nitrogen at 90 min and 24 h in ANP group was significantly lower than control group. Alanine transaminase and aspartate aminotransferase activity at 90 min in control group were significantly higher than that in sham group. However, hepatic enzyme activity at 90 min in ANP group was not significantly different compared with sham or control group. After 24 h, myocardial expression of caspase 3 protein in ANP group was significantly reduced compared with control group. Jejunal and hepatic Malondialdehyde was increased following ANP treatment. ANP therapy during early THS has no significant adverse effect on hemodynamics but can exert oxidative stress and certain protective effect on multiple organs. Our study may shed light on the novel therapy of THS with regard to organ protection. The mechanisms underlying the organ protection require further study.

The Endocrine Function of the Heart: Physiology and Involvements of Natriuretic Peptides and Cyclic Nucleotide Phosphodiesterases in Heart Failure

Besides pumping, the heart participates in hydro-sodium homeostasis and systemic blood pressure regulation through its endocrine function mainly represented by the large family of natriuretic peptides (NPs), including essentially atrial natriuretic (ANP) and brain natriuretic peptides (BNP). Under normal conditions, these peptides are synthesized in response to atrial cardiomyocyte stretch, increase natriuresis, diuresis, and vascular permeability through binding of the second intracellular messenger’s guanosine 3′,5′-cyclic monophosphate (cGMP) to specific receptors. During heart failure (HF), the beneficial effects of the enhanced cardiac hormones secretion are reduced, in connection with renal resistance to NP. In addition, there is a BNP paradox characterized by a physiological inefficiency of the BNP forms assayed by current methods. In this context, it appears interesting to improve the efficiency of the cardiac natriuretic system by inhibiting cyclic nucleotide phosphodiesterases, responsible for the degradation of cGMP. Recent data support such a therapeutic approach which can improve the quality of life and the prognosis of patients with HF.

NT-proBNP plasma levels as biomarkers for pulmonary hypertension in healthy infants with respiratory syncytial virus infection

Aim: To explore NT-proBNP as biomarker for pulmonary hypertension (PH) in infants with respiratory syncytial virus infection (RSVI). Patients & methods: We prospectively enrolled 93 healthy infants with RSVI aged 1-12 months. NT-proBNP determination and echocardiography were performed at admission. Results: PH was found in 22% of patients and associated with a severe course of the disease. NT-proBNP >1635 pg/ml resulted an independent predictor for PH (odds ratio: 16.46 [95% CI: 4.10-66; p < 0.001]). The diagnostic performance of NT-proBNP to detect PH in RSVI was high (area under receiver operator curve of 0.932 [95% CI: 0.883-0.981; p < 0.001]). Conclusions: The presence of PH in healthy infants with RSVI is associated with worse outcomes. NT-proBNP resulted an accurate biomarker for PH in this setting.

N-terminal probrain natriuretic peptide as biomarker for diagnosis of Kawasaki disease

Kawasaki disease (KD) is a systemic childhood vasculitis with peculiar tropism for the heart. Coronary artery aneurysms are the primary cause of morbidity and mortality in these patients. The timely administration of gammaglobulin decreases the risk for development of coronary artery aneurysms, highlighting the importance of early KD recognition. However, the most significant dilemma in the management of KD is the diagnosis itself. In this article, we review the recent literature focusing on the diagnostic utility of N-terminal probrain natriuretic peptide as a biomarker for diagnosis of KD. The main conclusion is that N-terminal probrain natriuretic peptide is an useful biomarker for KD diagnostic that represents a valuable addition to the current diagnostic workup of patients with suspected KD, increasing the diagnostic accuracy.

Localization profiles of natriuretic peptides in hearts of pre-hibernating and hibernating Anatolian ground squirrels (Spermophilus xanthoprymnus)

The Anatolian ground squirrel (Spermophilus xanthoprymnus) is a typical example of true mammalian hibernators. In order to adapt to extreme external and internal environments during hibernation, they lower their body temperatures, heart rates and oxygen consumption; however, pathological events such as ischemia and ventricular fibrillation do not occur in their cardiovascular systems. During the hibernation, maintenance of cardiac function is very important for survival of ground squirrels. Natriuretic peptides (NPs) are key factors in the regulation of cardiovascular hemostasis. Since NPs' role on the protection of heart during hibernation are less clear, the aim of this study was to investigate dynamic changes in NPs content in the cardiac chambers and to reveal the possible role of NPs on establishing cardiac function in ground squirrel during hibernation using immunohistochemistry. The immunohistochemical results indicate that cardiac NP expressions in atrial and ventricular cardiomyocytes were different from each other and were sex-independent. ANP and BNP were expressed in a chamber-dependent manner in female and male squirrel hearts. Furthermore, cardiac NPs expression levels in hibernation period were lower than those at the pre-hibernation period. During prehibernation period, ANP, BNP and CNP were expressed in the white and beige adipocytes of epicardial adipose tissue (EAT); while during hibernation period, the brown adipocytes of EAT were positive for BNP and CNP. These data suggest that the hibernation-dependent reduction in levels of NPs, particularly ANP, in cardiac chambers and EAT may be associated with low heart rate and oxygen consumption during hibernation. However, further studies are needed to better delineate the roles of NPs during the hibernation.

Plasmatic levels of N-terminal pro-atrial natriuretic peptide in preeclamptic patients and healthy normotensive pregnant women

BACKGROUND AND OBJECTIVE

To compare plasma N-terminal pro-atrial natriuretic peptide concentrations in preeclamptic patients and healthy normotensive pregnant women.

METHODS

A cases-controls study was done with 180 patients at Hospital Central Dr. Urquinaona, Maracaibo, Venezuela, that included 90 preeclamptic patients (group A; cases) and 90 healthy normotensive pregnant women selected with the same age and body mass index similar to group A (group B; controls). Blood samples were collected one hour after admission and prior to administration of any medication in group A to determine plasma N-terminal pro-atrial natriuretic peptide and other laboratory parameters.

RESULTS

Plasma N-terminal pro-atrial natriuretic peptide concentrations in group A (mean 1.01 [0.26] pg/mL) showed a significant difference when compared with patients in group B (mean 0.55 [0.07] pg/mL; P<.001]. There was no significant correlation with systolic and diastolic blood pressure values in preeclamptic patients (P=ns). A cut-off value of 0.66ng/mL had an area under the curve of 0.93, sensitivity of 87.8%, specificity of 83.3%, a positive predictive value of 84.0% and a negative predictive value of 87.2%, with a diagnostic accuracy of 85.6%.

CONCLUSION

Preeclamptic patients have significantly higher concentrations of plasma N-terminal pro-atrial natriuretic peptide compared with healthy normotensive pregnant women, with high predictive values for diagnosis.

Utility of Volume Assessment Using Bioelectrical Impedance Analysis in Critically Ill Patients Receiving Continuous Renal Replacement Therapy: A Prospective Observational Study

Background

Fluid overload prior to continuous renal replacement therapy (CRRT) is an important prognostic factor. Thus, precise evaluation of fluid status is necessary to treat such patients. In this study, we investigated whether fluid assessment using bioelectrical impedance analysis (BIA) can predict outcomes in critically ill patients requiring CRRT.

Methods

A prospective observational study was performed in patients who were admitted to the intensive care unit and who required CRRT. BIA was conducted before CRRT; then, the ratio of extracellular water to total body water (ECW/TBW) was derived to estimate volume status.

Results

A total of 31 patients treated with CRRT were included. There were 18 men (58.1%), and the median age was 67 years (interquartile range, 51 to 78 years). Fourteen patients (45.2%) died within 28 days after CRRT initiation. Patients were divided into 16 with ECW/TBW ≥0.41 and 15 with ECW/TBW <0.41. Survival rate within 28 days was different between the two groups (P = 0.044). Cox regression analysis revealed a relationship between ECW/TBW ≥0.41 and 28-day mortality, but it was not statistically significant (hazard ratio, 3.0; 95% confidence interval, 0.9 to 9.8; P = 0.061). Lastly, the area under the curve of ECW/TBW for 28-day mortality was analyzed. The area under the curve of ECW/TBW was 0.73 (95% confidence interval, 0.54 to 0.92), and this was significant (P = 0.037).

Conclusions

Fluid status can be assessed using BIA in critically ill patients requiring CRRT, and BIA can predict mortality. Further large trials are needed to confirm the usefulness of BIA in critically ill patients.

Brain natriuretic peptide and right heart dysfunction after heart transplantation

Heart transplantation (HT) should normalize cardiac endocrine function, but brain natriuretic peptide (BNP) levels remain elevated after HT, even in the absence of left ventricular hemodynamic disturbance or allograft rejection. Right ventricle (RV) abnormalities are common in HT recipients (HTx), as a result of engraftment process, tricuspid insufficiency, and/or repeated inflammation due to iterative endomyocardial biopsies. RV function follow-up is vital for patient management as RV dysfunction is a recognized cause of in-hospital death and is responsible for a worse prognosis. Interestingly, few and controversial data are available concerning the relationship between plasma BNP levels and RV functional impairment in HTx. This suggests that infra-clinical modifications, such as subtle immune system disorders or hypoxic conditions, might influence BNP expression. Nevertheless, due to other altered circulating molecular forms of BNP, a lack of specificity of BNP assays is described in heart failure patients. This phenomenon could exist in HT population and could explain elevated BNP plasmatic levels despite a normal RV function. In clinical practice, intra-individual change in BNP over time, rather than absolute BNP values, might be more helpful in detecting right cardiac dysfunction in HTx.

Changes of adrenomedullin and natriuretic peptides in patients with adrenal medullary hyperplasia prior to and following pharmacological therapy and adrenalectomy

The aim of the present study was to investigate the pathophysiological functions of adrenomedullin (ADM), atrial and brain natriuretic peptides (ANP and BNP) in patients with adrenal medullary hyperplasia (AMH). Plasma ADM, ANP and BNP concentrations were measured in 20 patients with AMH, 35 patients with essential hypertension (EH), and 40 healthy control subjects. Following effective antihypertensive therapy, the values in AMH and EH patients were measured again and laparoscopic adrenalectomy was performed for AMH patients. At 2 weeks after surgery, the three peptides were measured again. The AMH patients had higher plasma concentrations of ADM, ANP and BNP compared with the EH and control subjects. There were significant differences in the values of ADM, ANP and BNP between adrenal vein and inferior vena cava and between AMH and contralateral adrenal vein. Plasma ADM concentration was correlated with serum epinephrine and norepinephrine and urine vanillylmandelic acid, in addition to systolic and diastolic blood pressure, left ventricular ejection fraction, left ventricular mass index and ANP and BNP values in the AMH group. Following antihypertensive treatment, ADM, ANP and BNP were significantly decreased in EH patients, but remained unchanged in AMH subjects. However, these concentrations significantly decreased following surgery. Therefore, the present results suggest that ADM, ANP and BNP may be involved in regulating adrenal medulla functions.

Plasma concentrations of adrenomedullin and atrial and brain natriuretic peptides in patients with adrenal pheochromocytoma

The present study aimed to evaluate any changes in the plasma concentrations of adrenomedullin (ADM), atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) in patients with adrenal pheochromocytoma (PC). The plasma concentrations of the three peptides were measured in 45 healthy control individuals and 90 untreated patients with PC, who consisted of 20 normotensive patients, 30 borderline hypertensive patients and 40 hypertensive patients. After 4 weeks of effective antihypertensive therapy for hypertensive PC patients, the concentrations of ADM, ANP and BNP were measured again, and laparoscopic adrenalectomy was then performed for all PC patients with values that were measured 2 weeks later. The plasma concentrations of the three peptides were significantly increased in the borderline hypertensive and hypertensive patients compared with the concentrations in control individuals and normotensive patients. In addition, there were significant differences between the levels of ADM, ANP and BNP in the borderline and hypertensive groups. The plasma ADM concentration was not associated with the blood urea nitrogen levels, serum creatinine levels or glomerular filtration rate, but was correlated with the serum epinephrine, serum norepinephrine and urine vanillylmandelic acid levels. In addition, the ADM concentration was associated with the systolic blood pressure, diastolic blood pressure, left ventricular ejection fraction, left ventricular mass index and plasma concentrations of ANP and BNP in the hypertensive patients with PC. After 4 weeks of antihypertensive treatment, the values of the three peptides in the hypertensive patients with PC were not significantly changed. As expected, the values in borderline and hypertensive groups were significantly decreased 2 weeks subsequent to surgery, whereas there were no significant changes in the normotensive group. ADM may participate, along with ANP and BNP, in the mechanisms that counteract further elevation of blood pressure in patients with PC, and there may be an ADM/catecholamine local regulatory mechanism that is important for the control of adrenal medulla functions.

Effects of Atrial Natriuretic Peptide on Rat Ventricular Fibroblasts During Differentiation Into Myofibroblasts

Atrial natriuretic peptide antifibrotic properties are mainly described in cardiac myocytes or in induced cardiac myofibroblasts (Angiotensin II or TGF-β induced differentiation). In the present work, we investigate the effects of ANP/NPRA/cGMP system in modulating rat cardiac fibroblasts function. Cardiac fibroblasts were isolated from adult Wistar male rats and cultured in the presence of serum in order to induce fibroblasts differentiation. Cultures were then treated with ANP (1 µM), 8-Br-cGMP (100 µM) or IBMX (100 µM), a non-specific phosphodiesterases inhibitor. ANP significantly decreased proliferation rate and collagen secretion. Its effect was mimicked by the cGMP analog, while combining ANP with 8-Br-cGMP did not lead to additional effects. Moreover intracellular cGMP levels were elevated when cells were incubated with ANP confirming that ANP intracellular pathway is mediated by cGMP. Additionally, immunoblotting and immunofluorescence were used to confirm the presence of guanylyl cyclase specific natriuretic peptide receptors A and B. Finally we scanned specific cGMP dependent PDEs via RT-qPCR, and noticed that inhibiting all PDEs led to an important decrease in proliferation rate. Effect of ANP became more prominent after 10 culture days, confirming the importance of ANP in fibroblasts to myofibroblasts differentiation. Uncovering cellular aspects of ANP/NPRA/cGMP signaling system provided more elements to help understand cardiac fibrotic process.

Fluid overload at start of continuous renal replacement therapy is associated with poorer clinical condition and outcome: a prospective observational study on the combined use of bioimpedance vector analysis and serum N-terminal pro-B-type natriuretic peptide measurement

Introduction

It is unclear whether the fluid status, as determined by bioimpedance vector analysis (BIVA) combined with serum N-terminal pro-B-type natriuretic peptides (NT-pro-BNP) measurement, is associated with treatment outcome among patients receiving continuous renal replacement therapy (CRRT). Our objective was to answer this question.

Methods

Patients who were in the intensive care units of a university teaching hospital and who required CRRT were screened for enrollment. For the enrolled patients, BIVA and serum NT-pro BNP measurement were performed just before the start of CRRT and 3 days afterward. According to the BIVA and NT-pro BNP measurement results, the patients were divided into four groups according to fluid status type: type 1, both normal; type 2, normal BIVA results and abnormal NT-pro BNP levels; type 3, abnormal BIVA results and normal NT-pro BNP levels; and type 4, both abnormal. The associations between fluid status and outcome were analyzed.

Results

Eighty-nine patients were enrolled, 58 were males, and the mean age was 49.0 ± 17.2 years. The mean score of Acute Physiology and Chronic Health Evaluation II (APACHE II) was 18.8 ± 8.6. The fluid status before CRRT start was as follows: type 1, 21.3% (19 out of 89); type 2, 16.9% (15 out of 89); type 3, 11.2% (10 out of 89); and type 4, 50.6% (45 out of 89). There were significant differences between fluid status types before starting CRRT on baseline values for APACHE II scores, serum creatinine, hemoglobin, platelet count, urine volume, and incidences of oliguria and acute kidney injury (P <0.05). There were significant differences between patients with different fluid status before CRRT start on hospital mortality—type 1, 26.3% (5 out of 19); type 2, 33.3% (5 out of 15); type 3, 40% (4 out of 10); and type 4, 64.4% (29 out of 45) (P = 0.019)—as well as renal function recovery rates: type 1, 57.1% (4 out of 7); type 2, 67.7% (6 out of 9); type 3, 50% (3 out of 6); and type 4, 23.7% (9 out of 38) (P = 0.051).

Conclusions

Fluid status abnormalities were common among patients receiving CRRT. Different types of fluid status distinguished by BIVA combined with serum NT-pro BNP measurements corresponded to different clinical conditions and treatment outcomes, which implies a value of this method for evaluation of fluid status among patients receiving CRRT.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-015-0871-3) contains supplementary material, which is available to authorized users.

Swimming training promotes cardiac remodeling and alters the expression of mRNA and protein levels involved in calcium handling in hypertensive rats

AIM

The aim of this study was to identify the effects of swimming training on the mRNA expression and protein levels of the calcium handling proteins in the hearts of renovascular hypertensive rats submitted to swimming protocol during 6 weeks.

MAIN METHODS

Fischer rats with renovascular hypertension 2-kidney 1-clip (2K1C) and SHAM groups were divided among sedentary and exercised groups. The exercise protocol lasted for 6 weeks (1 h/day, 5×/week), and the mean arterial pressure, cardiomyocytes hypertrophy parameters, mRNA expression and protein levels of some calcium handling proteins in the left ventricle were evaluated.

KEY FINDINGS

Swimming training was able to reduce the levels of mean arterial pressure in the hypertensive group compared to 2K1C SED, and to promote cardiac hypertrophy in SHAM EX and 2K1C EX groups in comparison to the respective control groups. The mRNA levels of B-type natriuretic peptide were reduced in the 2K1C EX when compared to 2K1C SED. The mRNA and protein levels of the sarcoplasmic reticulum Ca2 +-ATPase increased after the swimming training in SHAM and 2K1C groups. The mRNA and protein levels of phospholamban, displayed an increase in their levels in the exercised SHAM and in hypertensive rats in comparison to their respective controls; while mRNA levels of Na+/Ca2 + exchanger was reduced in the left ventricle comparing to the sedentary hypertensive rats.

SIGNIFICANCE

Taken altogether, we provide evidence that the aerobic training may lead to cardiac remodeling, and modulate the calcium handling proteins expression in the heart of hypertensive rats.

B-type natriuretic peptide secretion without change in intra-cardiac pressure

OBJECTIVE

In clinical cardiology, B-type natriuretic peptide (BNP) is used as a non-invasive surrogate marker for intra-cardiac filling pressures, particularly in patients with heart failure. It is unknown whether and to what extent increase in intravascular volume and/or sympathetic tone while maintaining constant intra-cardiac pressures leads to an increase in levels of BNP in vivo.

DESIGN AND METHODS

We aimed to test this hypothesis in an experimental in vivo model of patients directly after off-pump coronary artery bypass grafting admitted to the intensive care unit. These patients require high volumes of intravenous fluids titrated to keep intra-cardiac filling pressures and arterial blood pressure in the normal range while awakening from deep general anesthesia. In 27 consecutive patients, intra-cardiac filling pressures (using a pulmonary artery catheter) and levels of BNP were measured simultaneously every 6h.

RESULTS

At 0, 6, 12, and 18h, the pulmonary capillary wedge pressure remained constant (12±4, 13±3, 12±3, and 13±3mmHg, respectively; p=0.351). Similarly, right heart filling pressures did not change during the study period. In contrast, BNP levels increased significantly during the study period: Median levels were 82 [IQR 37-162] pg/ml at 0h, 153 [92-246] pg/ml at 6h, 274 [156-392] pg/ml at 12h, and 320 [200-528] pg/ml at 18h (p<0.001). No significant correlation between BNP levels and pulmonary capillary wedge pressures was found (r=0.052; p=0.604).

CONCLUSIONS

After cardiac surgery, BNP cannot be considered a reliable non-invasive surrogate for PCWP. In vivo, substantial BNP secretion occurs independently of PCWP in a setting of increasing intravascular volume and consciousness/sympathetic tone.

Cardiac biomarkers for infarct diagnosis and early exclusion of acute coronary syndrome

The acute coronary syndrome (ACS) represents a diagnostic challenge: on the one hand patients need to be quickly identified to initiate treatment and on the other hand early exclusion of patients without ACS is important to relieve patient stress as well as overcrowded emergency departments. A growing number of biomarkers are becoming available to aid physicians with this task. This review gives an overview of the current research concerning early exclusion with an emphasis on the clinically most important biomarker: cardiac troponin.

The ultimate nanoscale mincer: assembly, structure and active sites of the 20S proteasome core

20S proteasomes constitute the proteolytic core of large protease complexes found in all branches of life. Among these, the eukaryotic 26S proteasome ubiquitously poses as a vital final entity in regulated degradation of intracellular proteins. The composition of 20S core particles has been disclosed in detail, facilitated by groundbreaking studies on ancestral prokaryotic 20S proteasomes of low complexity and culminated in the crystal structure determination of the much more complex eukaryotic particles. This article first summarizes insights into the structural organization of the 20S core followed by characterization of its proteolytic activities, which are confined to the central cavity of the particle. In eukaryotes they reside in three different subunit types differing in their preference for cleavage sites in substrates as well as in their importance for the proteasome's cellular function. The second part reviews current knowledge on the biogenesis pathways of 20S core particles, which have to ensure not only the fixed subunit arrangement but also activation of proteolytic subunits in a late assembly state.