C. Rocca

The NO stimulator, Catestatin, improves the Frank-Starling response in normotensive and hypertensive rat hearts.

The myocardial response to mechanical stretch (Frank-Starling law) is an important physiological cardiac determinant. Modulated by many endogenous substances, it is impaired in the presence of cardiovascular pathologies and during senescence. Catestatin (CST:hCgA352-372), a 21-amino-acid derivate of Chromogranin A (CgA), displays hypotensive/vasodilatory properties and counteracts excessive systemic and/or intra-cardiac excitatory stimuli (e.g., catecholamines and endothelin-1). CST, produced also by the myocardium, affects the heart by modulating inotropy, lusitropy and the coronary tone through a Nitric Oxide (NO)-dependent mechanism. This study evaluated the putative influence elicited by CST on the Frank-Starling response of normotensive Wistar-Kyoto (WKY) and hypertensive (SHR) hearts by using isolated and Langendorff perfused cardiac preparations. Functional changes were evaluated on aged (18-month-old) WKY rats and SHR which mimic human chronic heart failure (HF). Comparison to WKY rats, SHR showed a reduced Frank-Starling response. In both rat strains, CST administration improved myocardial mechanical response to increased end-diastolic pressures. This effect was mediated by EE/IP3K/NOS/NO/cGMP/PKG, as revealed by specific inhibitors. CST-dependent positive Frank-Starling response is paralleled by an increment in protein S-Nitrosylation. Our data suggested CST as a NO-dependent physiological modulator of the stretch-induced intrinsic regulation of the heart. This may be of particular importance in the aged hypertrophic heart, whose function is impaired because of a reduced systolic performance accompanied by delayed relaxation and increased diastolic stiffness.

Protective role of GPER agonist g-1 on cardiotoxicity induced by doxorubicin.

The use of Doxorubicin (Dox), a frontline drug for many cancers, is often complicated by dose‐limiting cardiotoxicity in approximately 20% of patients. The G‐protein estrogen receptor GPER/GPR30 mediates estrogen action as the cardioprotection under certain stressful conditions. For instance, GPER activation by the selective agonist G‐1 reduced myocardial inflammation, improved immunosuppression, triggered pro‐survival signaling cascades, improved myocardial mechanical performance, and reduced infarct size after ischemia/reperfusion (I/R) injury. Hence, we evaluated whether ligand‐activated GPER may exert cardioprotection in male rats chronically treated with Dox. 1 week of G‐1 (50 μg/kg/day) intraperitoneal administration mitigated Dox (3 mg/kg/day) adverse effects, as revealed by reduced TNF‐α, IL‐1β, LDH, and ROS levels. Western blotting analysis of cardiac homogenates indicated that G‐1 prevents the increase in p‐c‐jun, BAX, CTGF, iNOS, and COX2 expression induced by Dox. Moreover, the activation of GPER rescued the inhibitory action elicited by Dox on the expression of BCL2, pERK, and pAKT. TUNEL assay indicated that GPER activation may also attenuate the cardiomyocyte apoptosis upon Dox exposure. Using ex vivo Langendorff perfused heart technique, we also found an increased systolic recovery and a reduction of both infarct size and LDH levels in rats treated with G‐1 in combination with Dox respect to animals treated with Dox alone. Accordingly, the beneficial effects induced by G‐1 were abrogated in the presence of the GPER selective antagonist G15. These data suggest that GPER activation mitigates Dox‐induced cardiotoxicity, thus proposing GPER as a novel pharmacological target to limit the detrimental cardiac effects of Dox treatment. J. Cell. Physiol. 232: 1640–1649, 2017.

Quercetin derivatives as novel antihypertensive agents: Synthesis and physiological characterization

The antihypertensive flavonol quercetin (Q1) is endowed with a cardioprotective effect against myocardial ischemic damage. Q1 inhibits angiotensin converting enzyme activity, improves vascular relaxation, and decreases oxidative stress and gene expression. However, the clinical application of this flavonol is limited by its poor bioavailability and low stability in aqueous medium. In the aim to overcome these drawbacks and preserve the cardioprotective effects of quercetin, the present study reports on the preparation of five different Q1 analogs, in which all OH groups were replaced by hydrophobic functional moieties. Q1 derivatives have been synthesized by optimizing previously reported procedures and analyzed by spectroscopic analysis. The cardiovascular properties of the obtained compounds were also investigated in order to evaluate whether chemical modification affects their biological efficacy. The interaction with β-adrenergic receptors was evaluated by molecular docking and the cardiovascular efficacy was investigated on the ex vivo Langendorff perfused rat heart. Furthermore, the bioavailability and the antihypertensive properties of the most active derivative were evaluated by in vitro studies and in vivo administration (1month) on spontaneously hypertensive rats (SHRs), respectively. Among all studied Q1 derivatives, only the ethyl derivative reduced left ventricular pressure (at 10(-8)M÷10(-6)M doses) and improved relaxation and coronary dilation. NOSs inhibition by L-NAME abolished inotropism, lusitropism and coronary effects. Chronic administration of high doses of this compound on SHR reduced systolic and diastolic pressure. Differently, the acetyl derivative induced negative inotropism and lusitropism (at 10(-10)M and 10(-8)÷10(-6)M doses), without affecting coronary pressure. Accordingly, docking studies suggested that these compounds bind both β1/β2-adrenergic receptors. Taking into consideration all the obtained results, the replacement of OH with ethyl groups seems to improve Q1 bioavailability and stability; therefore, the ethyl derivative could represent a good candidate for clinical use in hypertension.

Obestatin regulates cardiovascular function and promotes cardioprotection through the nitric oxide pathway

Patients with ischaemic heart disease or chronic heart failure show altered levels of obestatin, suggesting a role for this peptide in human heart function. We have previously demonstrated that GH secretagogues and the ghrelin gene‐derived peptides, including obestatin, exert cardiovascular effects by modulating cardiac inotropism and vascular tone, and reducing cell death and contractile dysfunction in hearts subjected to ischaemia/reperfusion (I/R), through the Akt/nitric oxide (NO) pathway. However, the mechanisms underlying the cardiac actions of obestatin remain largely unknown. Thus, we suggested that obestatin‐induced activation of PI3K/Akt/NO and PKG signalling is implicated in protection of the myocardium when challenged by adrenergic, endothelinergic or I/R stress. We show that obestatin exerts an inhibitory tone on the performance of rat papillary muscle in both basal conditions and under β‐adrenergic overstimulation, through endothelial‐dependent NO/cGMP/PKG signalling. This pathway was also involved in the vasodilator effect of the peptide, used both alone and under stress induced by endothelin‐1. Moreover, when infused during early reperfusion, obestatin reduced infarct size in isolated I/R rat hearts, through an NO/PKG pathway, comprising ROS/PKC signalling, and converging on mitochondrial ATP‐sensitive potassium [mitoK(ATP)] channels. Overall, our results suggest that obestatin regulates cardiovascular function in stress conditions and induces cardioprotection by mechanisms dependent on activation of an NO/soluble guanylate cyclase (sGC)/PKG pathway. In fact, obestatin counteracts exaggerated β‐adrenergic and endothelin‐1 activity, relevant factors in heart failure, suggesting multiple positive effects of the peptide, including the lowering of cardiac afterload, thus representing a potential candidate in pharmacological post‐conditioning.

Phoenixin-14: detection and novel physiological implications in cardiac modulation and cardioprotection

Phoenixin-14 (PNX) is a newly identified peptide co-expressed in the hypothalamus with the anorexic and cardioactive Nesfatin-1. Like Nesfatin-1, PNX is able to cross the blood–brain barrier and this suggests a role in peripheral modulation. Preliminary mass spectrography data indicate that, in addition to the hypothalamus, PNX is present in the mammalian heart. This study aimed to quantify PNX expression in the rat heart, and to evaluate whether the peptide influences the myocardial function under basal condition and in the presence of ischemia/reperfusion (I/R). By ELISA the presence of PNX was detected in both hypothalamus and heart. In plasma of normal, but not of obese rats, the peptide concentrations increased after meal. Exposure of the isolated and Langendorff perfused rat heart to exogenous PNX induces a reduction of contractility and relaxation, without effects on coronary pressure and heart rate. As revealed by immunoblotting, these effects were accompanied by an increase of Erk1/2, Akt and eNOS phosphorylation. PNX (EC50 dose), administered after ischemia, induced post-conditioning-like cardioprotection. This was revealed by a smaller infarct size and a better systolic recovery with respect to those detected on hearts exposed to I/R alone. The peptide also activates the cardioprotective RISK and SAFE cascades and inhibits apoptosis. These effects were also observed in the heart of obese rats. Our data provide a first evidence on the peripheral activity of PNX and on its direct cardiomodulatory and cardioprotective role under both normal conditions and in the presence of metabolic disorders.

Editorial commentary: A chemically complex and unique beverage: The wine

h 1 In this issue of Trends in Cardiovascular Medicine, Haseeb and ollaborators [1] , summarize information sprouting from the “sohisticated branch of interconnected research encompassing the cience of winemaking, grape growing, and the analytical, organic, nd physical analysis of wine”, highlighting important aspects of ine history, production, classification and chemical composition. his work is an extension of a recent review published by the same uthors in Circulation [2] in which they focus on the good and the ad of wine consumption on human health. Several issues sustain the continuous effort of much laboratory esearch on wine. A major point of attention is the growing poplarity of this unique beverage and its large consumption worldide, with a consequent alert for human health. At the same time, pidemiological evidence and cross-cultural studies raise the hyothesis of a negative correlation between moderate wine conumption and ischemic heart disease (IHD) [3,4] . This seems to be articularly true in the case of red wine, due to its high content of olyphenols and other bioactive constituents [5,6] . In their review, Haseeb et al. [2] start from the well-accepted ssumption that bioactive red wine components, such as ethanol nd polyphenols, represent major elements of the beneficial casades activated by wine in the cardiovascular system. The authors ropose that these two compounds may elicit protection against hronic cardiovascular diseases only when acting synergically. This s the case of red wine in which both are highly present. Examles of these advantages are the improvement of lipid profile, the ncrease in HDL cholesterol, the reduction of blood pressure and latelet aggregation, and fibrinolysis induction, as observed uner the regular consumption of light-to-moderate amounts of red ine. [1,7,8] In line with this, the authors illustrate the peculiarity f the “French Paradox”, a condition resulting from a decreased in-

Notch1 Mediates Preconditioning Protection Induced by GPER in Normotensive and Hypertensive Female Rat Hearts

G protein-coupled estrogen receptor (GPER) is an estrogen receptor expressed in the cardiovascular system. G1, a selective GPER ligand, exerts cardiovascular effects through activation of the PI3K-Akt pathway and Notch signaling in normotensive animals. Here, we investigated whether the G1/GPER interaction is involved in the limitation of infarct size, and improvement of post-ischemic contractile function in female spontaneous hypertensive rat (SHR) hearts. In this model, we also studied Notch signaling and key components of survival pathway, namely PI3K-Akt, nitric oxide synthase (NOS) and mitochondrial K+-ATP (MitoKATP) channels. Rat hearts isolated from female SHR underwent 30 min of global, normothermic ischemia and 120 min of reperfusion. G1 (10 nM) alone or specific inhibitors of GPER, PI3K/NOS and MitoKATP channels co-infused with G1, just before I/R, were studied. The involvement of Notch1 was studied by Western blotting. Infarct size and left ventricular pressure were measured. To confirm endothelial-independent G1-induced protection by Notch signaling, H9c2 cells were studied with specific inhibitor, N-[N-(3,5 difluorophenacetyl)-L-alanyl]-S-phenylglycine t-butyl ester (DAPT, 5 μM), of this signaling. Using DAPT, we confirmed the involvement of G1/Notch signaling in limiting infarct size in heart of normotensive animals. In the hypertensive model, G1-induced reduction in infarct size and improvement of cardiac function were prevented by the inhibition of GPER, PI3K/NOS, and MitoKATP channels. The involvement of Notch was confirmed by western blot in the hypertensive model and by the specific inhibitor in the normotensive model and cardiac cell line. Our results suggest that GPERs play a pivotal role in mediating preconditioning cardioprotection in normotensive and hypertensive conditions. The G1-induced protection involves Notch1 and is able to activate the survival pathway in the presence of comorbidity. Several pathological conditions, including hypertension, reduce the efficacy of ischemic conditioning strategies. However, G1-induced protection can result in significant reduction of I/R injury also female in hypertensive animals. Further studies may ascertain the clinical translation of the present results.

Role of NLRP-3 Inflammasome in Hypertension: a Potential Therapeutic Target

BACKGROUND Hypertension is a multifactorial and chronic cardiovascular condition whose complications are responsible for worldwide morbidity and mortality. An increasing body of experimental data, recognize low-grade inflammation as a basic process in hypertension onset and development since there is a strong contribution of both the innate and the adaptive immune system according to the so-called Danger-Model. In this contest, NLRP3 inflammasome represents a key signaling platform as demonstrated by its implication in several hypertension-associated conditions, such as vascular smooth muscle remodeling and proliferation. This intracellular receptor is activated by Pathogenassociated molecular pattern molecules/damage-associated molecular pattern molecules signals and its mechanism of action converges on the final production of caspase-1 and, consequently, of the proinflammatory cytokines IL-1β and IL-18. OBJECTIVE The aim of the present work was to point out the role of the NLRP3 inflammasome complex in the hypertensive pathology and to describe it as a new potential therapeutic target. METHOD A systematic review of the literature data related to NLRP3 and hypertension correlation has been performed. RESULTS Numerous and well-designed experiments demonstrate that the inflammasome plays a crucial role in essential and high-salt dependent hypertension, as well as in preeclampsia, in pulmonary hypertension, and in its related secondary disorders; its mechanism includes both a central nervous and a peripheral modulation of the inflammatory pathways. To date, research is trying to design inflammasome antagonists or equivalent inhibition strategies. CONCLUSION The inflammasome represents a leading promoter of hypertensive inflammation opening new perspective in the field of the clinical approach in this pathology.