Insulin blunts the natriuretic action of atrial natriuretic peptide in hypertension

New Conversion Formula Between B-Type Natriuretic Peptide and N-Terminal-Pro-B-Type Natriuretic Peptide - Analysis From a Multicenter Study

BACKGROUND

Although B-type natriuretic peptide (BNP) and N-terminal (NT)-proBNP are commonly used markers of heart failure, a simple conversion formula between these peptides has not yet been developed for clinical use.

METHODS AND RESULTS

A total of 9,394 samples were obtained from Nara Medical University, Jichi Medical University, and Osaka University. We randomly selected 70% for a derivation set to investigate a conversion formula from BNP to NT-proBNP using estimated glomerular filtration rate (eGFR) and body mass index (BMI); the remaining 30% was used as the internal validation set and we used a cohort study from Nara Medical University as an external validation set. Multivariate linear regression analysis revealed a new conversion formula: log NT-proBNP = 1.21 + 1.03 × log BNP - 0.009 × BMI - 0.007 × eGFR (r2=0.900, P<0.0001). The correlation coefficients between the actual and converted values of log NT-proBNP in the internal and external validation sets were 0.942 (P<0.0001) and 0.891 (P<0.0001), respectively. We applied this formula to samples obtained from patients administered with sacubitril/valsartan. After treatment initiation, NT-proBNP levels decreased and actual BNP levels increased. However, the calculated BNP levels decreased roughly parallel to the NT-proBNP levels.

CONCLUSIONS

This new and simple conversion formula of BNP and NT-proBNP with eGFR and BMI is potentially useful in clinical practice.

Early ICU-acquired hypernatraemia is associated with injury severity and preceded by reduced renal sodium and chloride excretion in polytrauma patients

PURPOSE

To further elucidate the origin of early ICU-acquired hypernatraemia.

MATERIAL AND METHODS

In this retrospective single-centre study, polytrauma patients requiring ICU treatment were analysed.

RESULTS

Forty-eight (47.5%) of 101 included polytrauma patients developed hypernatraemia within the first 7 days on ICU. They were more severely ill as described by higher SAPS III, ISS, daily SOFA scores and initial norepinephrine requirements as well as longer requirements of mechanical ventilation and ICU treatment in general. The development of hypernatraemia was neither attributable to fluid- or sodium-balances nor renal impairment. Although lower in the hypernatraemic group from day 4 onwards, median creatinine clearances were sufficiently high throughout the observation period. However, in the hypernatraemic group, urine sodium and chloride concentrations prior to the evolvement of hypernatraemia (56 (27-87) mmol/l and 39 (23-77) mmol/l) were significantly decreased when compared to i) the time after developing hypernatraemia (94 (58-134) mmol/l and 78 (36-115) mmol/l; p < 0.001) and ii) the non-hypernatraemic group in general (101 (66-143) mmol/l and 75 (47-109) mmol/l; p < 0.001).

CONCLUSIONS

Early ICU-acquired hypernatraemia is associated with injury severity and preceded by reduced renal sodium and chloride excretion in polytrauma patients.

High percent body fat mass predicts lower risk of cardiac events in patients with heart failure: an explanation of the obesity paradox

Background

Although high body mass index (BMI) is a risk factor of heart failure (HF), HF patients with a higher BMI had a lower mortality rate than that in HF patients with normal or lower BMI, a phenomenon that has been termed the “obesity paradox”. However, the relationship between body composition, i.e., fat or muscle mass, and clinical outcome in HF remains unclear.

Methods

We retrospectively analyzed data for 198 consecutive HF patients (76 years of age; males, 49%). Patients who were admitted to our institute for diagnosis and management of HF and received a dual-energy X-ray absorptiometry scan were included regardless of left ventricular ejection fraction (LVEF) categories. Muscle wasting was defined as appendicular skeletal muscle mass index < 7.0 kg/m² in males and < 5.4 kg/m² in females. Increased percent body fat mass (increased FM) was defined as percent body fat > 25% in males and > 30% in females.

Results

The median age of the patients was 76 years (interquartile range [IQR], 67–82 years) and 49% of them were male. The median LVEF was 47% (IQR, 33–63%) and 33% of the patients had heart failure with reduced ejection fraction. Increased FM and muscle wasting were observed in 58 and 67% of the enrolled patients, respectively. During a 180-day follow-up period, 32 patients (16%) had cardiac events defined as cardiac death or readmission by worsening HF or arrhythmia. Kaplan-Meier survival curves showed that patients with increased FM had a lower cardiac event rate than did patients without increased FM (11.4% vs. 22.6%, p = 0.03). Kaplan-Meier curves of cardiac event rates did not differ between patients with and those without muscle wasting (16.5% vs. 15.4%, p = 0.93). In multivariate Cox regression analyses, increased FM was independently associated with lower cardiac event rates (hazard ratio: 0.45, 95% confidence interval: 0.22–0.93) after adjustment for age, sex, diabetes, muscle wasting, and renal function.

Conclusions

High percent body fat mass is associated with lower risk of short-term cardiac events in HF patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12877-020-01950-9.

B-type natriuretic peptide levels and benign adiposity in obese heart failure patients

Obesity is a major risk factor for the development of chronic heart failure (CHF) and does not only pose diagnostic challenges, but also has prognostic implications for these patients. Paradoxically, obese patients with CHF have a better prognosis than thinner individuals. In recent years, it has been demonstrated that the adipose tissue, even in patients with HF, is not always detrimental, and that obesity may coexist with a phenotype of benign adiposity without systemic metabolic abnormalities. Experimental data have shown that natriuretic peptides (NPs), and in particular brain natriuretic peptide (BNP), play a major role in the communication of the heart with the adipose tissue. Body fat distribution and adipose tissue function show a large degree of heterogeneity among depots and may explain the complex relationship between NPs and body fat. NPs can affect both the quality and the behaviour of fatty tissue, promoting a healthy adipocyte phenotype, and can favourably affect body fat metabolism. In this article, we review the existing literature on the bidirectional effects of BNP and adipose tissue in HF and highlight the complexity of this relationship.

Natriuretic peptides in the control of lipid metabolism and insulin sensitivity

Natriuretic peptides have long been known for their cardiovascular function. However, a growing body of evidence emphasizes the role of natriuretic peptides in human substrate and energy metabolism, thereby connecting the heart with several insulin-sensitive organs like adipose tissue, skeletal muscle and liver. Obesity may be associated with an impaired regulation of the natriuretic peptide system, also indicated as a natriuretic handicap. Evidence points towards a contribution of this natriuretic handicap to the development of obesity, type 2 diabetes mellitus and cardiometabolic complications, although the causal relationship is not fully understood. Nevertheless, targeting the natriuretic peptide pathway may improve metabolic health in obesity and type 2 diabetes mellitus. This review will focus on current literature regarding the metabolic roles of natriuretic peptides with emphasis on lipid metabolism and insulin sensitivity. Furthermore, it will be discussed how exercise and lifestyle intervention may modulate the natriuretic peptide-related metabolic effects.

The role of natriuretic peptides in diabetes and its complications

This review aimed to summarize recent findings on the role of natriuretic peptides (NPs) in diabetes and its important complications. Although the treatment of diabetes mellitus has benefited from recent advances, aggressive glycemic control can increase the risk of hypoglycemia and weight gain. Therefore, innovative therapies are required to address this issue. Natriuretic peptides (NPs) may have such novel therapeutic potential. NPs comprise a family of structurally related peptides, including atrial, brain, C-type, and dendroaspis. Each of these NPs has a wide range of specific functions to regulate and maintain cardiovascular, renal, and endocrine homeostasis. NPs exert their effects by interacting with three receptor subtypes including NPR-A, NPR-B, and NPR-C. The coronary NP system has been suggested to be involved in regulating water and salt balance, as well as vascular remodeling. In this review, we provide evidence that NPs play an important role in diabetes mellitus and its related complications including macrovascular and microvascular disorders. NPs hold promise as markers for early diagnosis, risk assessment, and intervention guidance in diabetes and its complications and may thus improve diabetes care.

Obesity and natriuretic peptides, BNP and NT-proBNP: mechanisms and diagnostic implications for heart failure

Many advances have been made in the diagnosis and management of heart failure (HF) in recent years. Cardiac biomarkers are an essential tool for clinicians: point of care B-type natriuretic peptide (BNP) and its N-terminal counterpart (NT-proBNP) levels help distinguish cardiac from non-cardiac causes of dyspnea and are also useful in the prognosis and monitoring of the efficacy of therapy. One of the major limitations of HF biomarkers is in obese patients where the relationship between BNP and NT-proBNP levels and myocardial stiffness is complex. Recent data suggest an inverse relationship between BNP and NT-proBNP levels and body mass index. Given the ever-increasing prevalence of obesity world-wide, it is important to understand the benefits and limitations of HF biomarkers in this population. This review will explore the biology, physiology, and pathophysiology of these peptides and the cardiac endocrine paradox in HF. We also examine the clinical evidence, mechanisms, and plausible biological explanations for the discord between BNP levels and HF in obese patients.

Relation of visceral adiposity to circulating natriuretic peptides in ambulatory individuals

Natriuretic peptides have important roles in the regulation of vasomotor tone, salt homeostasis, and ventricular remodeling. Lower natriuretic peptide levels observed in obese individuals may underlie the greater cardiovascular risk associated with obesity. Thus the aim of this study was to determine whether lower natriuretic peptide levels in obesity are attributable to differences in regional fat distribution. We investigated the relation of plasma N-terminal pro-B-type natriuretic peptide (NT-pro-BNP) to regional adiposity in 1,873 community-based individuals (46% women, mean age 45 years). Subcutaneous adipose tissue (SAT) and visceral adipose tissue (VAT) volumes were measured by multidetector computed tomography. In gender-specific multivariable analyses adjusting for age and blood pressure, log NT-pro-BNP was inversely associated with VAT in men (beta -0.11 per standard deviation increment, p <0.001) and women (beta -0.19, p <0.001). Log NT-pro-BNP was inversely associated with SAT in women only (beta -0.14, p <0.001). In models containing VAT and SAT, only VAT was significantly associated with log NT-pro-BNP (men, beta -0.137, p <0.001; women, beta -0.184, p <0.001). VAT remained associated with log NT-pro-BNP even after adjustment for body mass index and waist circumference (beta -0.119, p <0.001) and in analyses restricted to nonobese patients (beta -0.165, p <0.001). Adjustment for insulin resistance attenuated the associations of NT-pro-BNP with VAT and SAT. In conclusion, this study demonstrates that circulating NT-pro-BNP is related to variations in regional and particularly visceral adiposity. These findings suggest that excess visceral adiposity and concomitant hyperinsulinemia may contribute to the natriuretic peptide "deficiency" observed in obesity.

Correlation of sodium-related factors with insulin sensitivity in young, lean, male offspring of hypertensive and normotensive subjects

Pioneer studies have proposed that multiple metabolic abnormalities, such as insulin resistance, increased Na(+)-H(+) exchanger activity and abnormal intracellular calcium homeostasis, are frequently associated with a subset of essential hypertensive patients with low plasma renin activity (PRA). However, it is unclear whether insulin resistance is related to the low renin status in the very early phase of genetical hypertension. Besides, there is controversy on the subject of the in vivo effect of acute hyperinsulinaemia on sodium-related factors. We investigated the relationship between sodium-related parameters and insulin sensitivity, and the effects of euglycaemic hyperinsulinaemia on cyclic guanosine monophosphate (cGMP) and atrial natriuretic peptide (ANP) levels in 17 young, lean, normotensive male subjects, who displayed extreme predispositions for the development of hypertension. PRA was significantly lower in the positive than in the negative family history group (P < 0.05). Insulin sensitivity (M-value) was correlated with PRA before euglycaemic hyperinsulinaemic clamping (r = 0.577, P < 0.05), and was also inversely correlated with fractional excretion of sodium (FE(Na)) before clamping (r = -0.51, P < 0.05). Euglycaemic hyperinsulinaemia significantly decreased PRA (P < 0.0001) and increased cGMP (P < 0.05) and ANP levels (P < 0.01). In conclusion, insulin sensitivity may be partially determined by PRA levels and FE(Na) before clamping in young, lean, normotensive male subjects. Acute euglycaemic hyperinsulinaemia decreases PRA, and increases cGMP and ANP levels from the fasting condition.

Insulin effect on renal sodium reabsorption in adolescent offspring of essential hypertensive parents

We previously showed that children and adolescent offspring of patients with essential hypertension have an increased proximal renal sodium reabsorption as measured by lithium fractional excretion. Insulin has been shown to have antinatriuretic properties and to be increased (hyperinsulinemia) in essential hypertension. The aim of this study was to evaluate the role of insulin on the increased proximal renal sodium reabsorption previously reported. Lithium and sodium fractional excretions were measured 3 hours before and 3 hours after an intravenous glucose tolerance test in 20 normotensive adolescents with a family history of essential hypertension (F+, 14.8 +/- 0.5 years) and 10 normotensive control subjects without a family history of hypertension (F-, 15.2 +/- 0.9 years). Results are mean +/- SEM. Lithium fractional excretion before glucose loading was 16.1 +/- 1.8% in F+ versus 23.5 +/- 2.0% in F- (P < .02) and after glucose loading was 14.7 +/- 1.3% in F+ versus 20.9 +/- 1.7% in F- (P = NS). Lithium fractional excretion did not change after intravenous glucose loading in either group. The insulin area under the curve was 2815 +/- 499 in F+ versus 2290 +/- 418 microU/mL per hour in F- (P = NS). There was no correlation between lithium fractional excretion and insulin area under the curve. Fractional excretion of sodium before glucose loading was 0.99 +/- 0.1% in F+ versus 0.99 +/- 0.1% in F- (P = NS) and after glucose loading was 0.77 +/- 0.1 in F+ versus 0.85 + 0.1% in F- (P < .01 versus values before loading in both groups).(ABSTRACT TRUNCATED AT 250 WORDS)