Cessation of pulmonary and coronary secretion of adrenomedullin peptides in the progression of human heart failure

Mid-regional pro-adrenomedullin (MR-proADM) and mid-regional pro-atrial natriuretic peptide (MR-proANP) in severe aortic valve stenosis: association with outcome after transcatheter aortic valve implantation (TAVI)

BACKGROUND

This study aimed to assess the association of mid-regional (MR) pro-adrenomedullin (MR-proADM) and MR-pro-A-type natriuretic peptide (MR-proANP) in comparison to N-terminal pro-natriuretic peptide (NT-proBNP) with outcome in patients with aortic stenosis (AS) treated with transcatheter aortic valve implantation (TAVI).

METHODS

One hundred consecutive TAVI patients were included in this prospective study. Association of preinterventional levels of MR-proADM, MR-proANP, NT-proBNP, C-reactive protein (CrP), and high-sensitive cardiac Troponin T (hsTN) with 30-day and 1-year outcome was analyzed.

RESULTS

There was no association with 30-day outcome, but all markers were associated with 1-year cardiovascular events and all-cause mortality. The combined biomarker analysis further improved risk prediction.

CONCLUSIONS

In TAVI patients MR-proADM, MR-proANP, and NT-proBNP are promising predictors of adverse events within 1 year. Integration of these biomarkers into decision pathways may help to identify patients at higher risk.

Adrenomedullin limits reperfusion injury in experimental myocardial infarction

Adrenomedullin (AM) is a vascular-derived polypeptide that exerts numerous actions in cardiovascular homeostasis. Recent studies have demonstrated a cytoprotective action of exogenously applied or genetically over-expressed AM in experimental myocardial infarction. The present studies were undertaken to test the hypothesis that AM exerts its effects through direct augmentation of NO generation in the myocardium during early reperfusion. Rat isolated hearts underwent 35 min left coronary artery occlusion followed by 120 min reperfusion. Infarct size (as percentage of ischaemic riskzone) was determined by Evans' blue and tetrazolium double staining. AM 1 nM administered 5 min prior to and during the first 15 min of ischaemia did not significantly influence infarct size. However, the same concentration of AM given during the last 5 min ischaemia and first 15 min of reperfusion significantly limited infarct size (AM reperfusion 15.9 +/- 3.5% vs control 31.4 +/- 2.1%, P < 0.01). AM at reperfusion improved coronary flow and LV contractility. The protective effects of adrenomedullin were abolished in the presence of the NO synthase inhibitor, L-NAME 100 microM (infarct size 24.6 +/- 5.7%, P > 0.05 vs control). AM treatment at reperfusion was associated with augmented phosphorylation of the pro-survival kinase, Akt, determined by immunoblotting of tissue sampled 30 min following reperfusion. These studies provide the first evidence that AM exerts its cytoprotective action specifically during early reperfusion through a NO-dependent mechanism.

Adrenomedullin: regulator of systemic and cardiac homeostasis in acute myocardial infarction

During and following acute myocardial infarction, a variety of endogenous mediators are elevated, one of which is adrenomedullin (AM). AM is a multifunctional peptide that has been identified as having a putative beneficial role following an ischemic insult at both systemic and local levels. Classically described as a potent vasodilator, natriuretic, and diuretic agent, experimental infarct models also demonstrate AM to exhibit antiproliferative and antiapoptotic functions in the myocardium, counterregulating the effects of mediators such as angiotensin-II and endothelin-1. Less well documented are the angiogenic and inflammatory modulating potentials of AM, which may also contribute toward reducing adverse ventricular remodeling. The review examines clinical and experimental studies, looking at the effects of AM and cellular mechanisms that could be involved in mediating cardioprotective effects and ultimately optimizing left ventricular remodeling. Finally, the possibility of enhancing endogenous actions of AM by pharmacological intervention is considered.

Cardiomyopathy in streptozotocin-induced diabetes involves intra-axonal accumulation of calcitonin gene-related peptide and altered expression of its receptor in rats

Calcitonin gene-related peptide (CGRP) is a vasorelaxant and positive inotropic and chronotropic peptide that binds to the calcitonin receptor-like receptor. In the heart, upon stimulation CGRP is released from sensory nerve terminals and improves cardiac perfusion and function. In the present study, we investigated alterations in the components of the CGRP signaling system during development of diabetic cardiomyopathy. Rats received a single injection of streptozotocin. Four, 8, and 16 weeks thereafter cardiac CGRP content (radioimmunoassay), calcitonin receptor-like receptor expression (by real-time RT-PCR), and CGRP and calcitonin receptor-like receptor tissue distribution (immunohistochemistry) were assessed. CGRP content of atria and ventricles progressively increased during the 4 months following streptozotocin-treatment, while the distribution of CGRP-immunoreactive fibers was not visibly altered. Conversely, cardiac expression of calcitonin receptor-like receptor initially (4 weeks after treatment) increased but then gradually declined to 47% of control levels in both atria after 16 weeks. These quantitative changes were not associated with altered cellular distribution patterns (primarily in venous and capillary endothelium). Since sensory neurons have been reported to decrease expression of the CGRP precursor in the course of diabetes, the intra-axonal accumulation of CGRP observed here reflects impaired release, which, coupled with the down-regulation of its cognate receptor, calcitonin receptor-like receptor, may contribute to the well-documented impairment of cardioprotective functions in diabetes.

Impact of nitric oxide on adrenomedullin- and proadrenomedullin N-terminal 20 peptide-induced cardiac responses: action by alone and combined administration

The cardiac effects of adrenomedullin (AM) and proadrenomedullin N-terminal 20 peptide (PAMP) as well as the possible signaling pathways were investigated. In the isolated perfused rat heart, infusion of AM (10(-11) to 10(-8) M) and PAMP(10(-11) to 10(-8) M) for 10 min, alone or in combination, induced concentration-dependent decreases in the left ventricular pressure (LVP), LVP +/- dp/dtmax of the hearts. The effects were attenuated by Nomega-nitro-L-arginine methyl ester (L-NAME), an inhibitor of nitric oxide (NO) synthase. ADM and PAMP alone or in combinations increased the coronary fluid (CF), which could be antagonized by L-NAME. Pretreatment of H89, an inhibitor of protein kinase A (PKA), failed to alter the AM- or PAMP-induced decreases in LVP and LVP +/- dp/dtmax, but further promoted the AM or PAMP increased CF. The cAMP content in left cardiac ventricle was increased significantly by ADM infusions but not by PAMP. There was no statistical difference in cAMP contents with ADM administrated alone from those combined with ADM and PAMP. In conclusion, this study reveals that ADM and PAMP infused alone or in combinations inhibited the function of rat hearts in vitro, which may be partly involved with the NOS/NO pathway, rather than cAMP/PKA.