Lipolytic effects of B-type natriuretic peptide 1-32 in adipose tissue of heart failure patients compared with healthy controls

Prevalence of cachexia in chronic heart failure and characteristics of body composition and metabolic status

The prevalence of cardiac cachexia has previously been estimated to 8-42 %. However, novel treatment strategies for chronic heart failure (CHF) have improved and decreased morbidity and mortality. Therefore, we aimed to reassess the prevalence of cachexia in an outpatient CHF clinic and to characterize a CHF population with and without cachexia with respect to body composition and related biomarkers. From 2008 to 2011, we screened 238 optimally treated, non-diabetic CHF patients for cardiac cachexia, defined as unintentional non-oedematous weight loss of >5 % over ≥6 months. CHF patients (LVEF <45 %) with cachexia (n = 19) and without (n = 19) were compared to controls with prior myocardial infarction and left ventricular ejection fraction (LVEF) >45 % (n = 19). The groups were matched for age, sex, and kidney function. Body composition was assessed by dual energy X-ray absorptiometry. The prevalence of cachexia was 10.5 %. Abdominal fat ± SD (%) was reduced in cachectic CHF: 27.4 ± 10.0 versus 37.5 ± 10.6 % (CHF, no cachexia) and 40.6 ± 8.0 % (controls), (P < 0.001). NT-proBNP levels were inversely correlated to abdominal fat in a multivariate linear regression analysis adjusted for known predictors of NT-proBNP (LVEF and NYHA); (β = -0.28; P = 0.018). Myostatin levels were reduced in cachectic CHF compared to controls (P = 0.013). The prevalence of cachexia in stable CHF, treated according to recent guidelines, is lower than previously anticipated. Body alterations in cachexia consist mainly of reduced abdominal fat mass, and its inverse correlation to NT-proBNP suggests involvement of abdominal lipolysis. Our data do not support a role of circulating myostatin as a biomarker for muscle wasting.

Natriuretic peptides and cGMP signaling control of energy homeostasis

Since the discovery of natriuretic peptides (NPs) by de Bold et al. in 1981, the cardiovascular community has been well aware that they exert potent effects on vessels, heart remodeling, kidney function, and the regulation of sodium and water balance. Who would have thought that NPs are also able to exert metabolic effects and contribute to an original cross talk between heart, adipose tissues, and skeletal muscle? The attention on the metabolic role of NPs was awakened in the year 2000 with the discovery that NPs exert potent lipolytic effects mediated by the NP receptor type A/cGMP pathway in human fat cells and that they contribute to lipid mobilization in vivo. In this review, we will discuss the biological effects of NPs on the main tissues involved in the regulation of energy metabolism (i.e., white and brown adipose tissues, skeletal muscle, liver, and pancreas). These recent results on NPs are opening a new chapter into the physiological properties and therapeutic usefulness of this family of hormones.

Atrial natriuretic peptide and adiponectin interactions in man

Reduced circulating natriuretic peptide concentrations are independently associated with insulin resistance and type 2 diabetes, while increased natriuretic peptide levels appear to be protective. Observations in vitro and in heart failure patients suggest that atrial natriuretic peptide (ANP) promotes adiponectin release, an adipokine with insulin sensitizing properties. We tested the hypothesis that ANP acutely raises adiponectin levels in 12 healthy men. We infused ANP intravenously over 135 minutes while collecting venous blood and adipose tissue microdialysates at baseline and at the end of ANP-infusion. We obtained blood samples at identical time-points without ANP infusion in 7 age and BMI matched men. With infusion, venous ANP concentrations increased ∼10 fold. Systemic and adipose tissue glycerol concentrations increased 70% and 80%, respectively (P<0.01). ANP infusion increased total adiponectin 14 ± 5% and high molecular-weight (HMW)-adiponectin 13 ± 5% (P<0.05). Adiponectin did not change in the control group (P<0.05 vs. infusion). ANP-induced changes in HMW adiponectin and adipose tissue lipolysis were directly correlated with each other, possibly suggesting a common mechanism. Our data show that ANP acutely increases systemic total and HMW-adiponectin concentrations in healthy subjects. Our study could have implications for the physiological regulation of adiponectin and for disease states associated with altered natriuretic peptide availability.

B-type natriuretic peptide (BNP) affects the initial response to intravenous glucose: a randomised placebo-controlled cross-over study in healthy men

AIMS/HYPOTHESIS

B-type natriuretic peptide (BNP) is a hormone released from cardiomyocytes in response to cell stretching and elevated in heart failure. Recent observations indicate a distinct connection between chronic heart failure and diabetes mellitus. This study investigated the role of BNP on glucose metabolism.

METHODS

Ten healthy volunteers (25 ± 1 years; BMI 23 ± 1 kg/m(2); fasting glucose 4.6 ± 0.1 mmol/l) were recruited to a participant-blinded investigator-open placebo-controlled cross-over study, performed at a university medical centre. They were randomly assigned (sequentially numbered opaque sealed envelopes) to receive either placebo or 3 pmol kg(-1) min(-1) BNP-32 intravenously during 4 h on study day 1 or 2. One hour after beginning the BNP/placebo infusion, a 3 h intravenous glucose tolerance test (0.33 g/kg glucose + 0.03 U/kg insulin at 20 min) was performed. Plasma glucose, insulin and C-peptide were frequently measured.

RESULTS

Ten volunteers per group were analysed. BNP increased the initial glucose distribution volume (13 ± 1% body weight vs 11 ± 1%, p < 0.002), leading to an overall reduction in glucose concentration (p < 0.001), particularly during the initial 20 min of the test (p = 0.001), accompanied by a reduction in the initial C-peptide levels (1.42 ± 0.13 vs 1.62 ± 0.10 nmol/l, p = 0.015). BNP had no impact on beta cell function, insulin clearance or insulin sensitivity and induced no adverse effects.

CONCLUSIONS/INTERPRETATION

Intravenous administration of BNP increases glucose initial distribution volume and lowers plasma glucose concentrations following a glucose load, without affecting beta cell function or insulin sensitivity. These data support the theory that BNP has no diabetogenic properties, but improves metabolic status in men, and suggest new questions regarding BNP-induced differences in glucose availability and signalling in various organs/tissues.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT01324739

FUNDING

The study was funded by Jubilée Fonds of the Austrian National Bank (OeNB-Fonds).

B-type natriuretic peptide and glycaemia: an emerging cardiometabolic pathway?

There is emerging evidence of cross-talk between the myocardium and systemic metabolic pathways. In particular, there is interest in the potential metabolic effects of A-type and B-type natriuretic peptides (ANP and BNP), produced in the myocardial tissue in response to ventricular stretch and cardiac overload. This commentary provides an overview of the evidence that natriuretic peptides promote lipolysis and enhance adiponectin production. In addition, we review new and existing evidence that BNP may directly improve glucose control, or else lower glucose indirectly via enhanced capillary permeability or greater renal excretion. Further investigation of the links between natriuretic peptide and glycaemia would seem important given the potential to reveal novel mechanisms to treat diabetes.