Myocardial Phosphodiesterases and their Role in cGMP Regulation Cyclic nucleotide phosphodiesterases comprise an 11-member superfamily yielding near 100 isoform variants that hydrolyze cAMP or cGMP to their respective 5’-monophosphate form. Each plays a role in compartmentalized cyclic nucleotide signaling, with varying selectivity for each substrate, and conveying cell and intracellular specific localized control. This review focuses on the five PDEs expressed in the cardiac myocyte capable of hydrolyzing cGMP and that have been shown to play a role in cardiac physiological and pathological processes. PDE1, PDE2, and PDE3 catabolize cAMP as well, whereas PDE5 and PDE9 are cGMP selective. PDE3 and PDE5 are already in clinical use, the former for heart failure, and PDE1, PDE9, and PDE5 are all being actively studied for this indication in patients. Research in just the past few years has revealed many novel cardiac influences of each isoform, expanding the therapeutic potential from their selective pharmacological blockade or in some instances, activation. PDE1C inhibition was found to confer cell survival protection and enhance cardiac contractility, while PDE2 inhibition or activation induces beneficial effects in hypertrophied or failing hearts, respectively. PDE3 inhibition is already clinically employed to treat acute decompensated heart failure, though toxicity has precluded its long-term use. However, newer approaches including isoform specific allosteric modulation may change this. Lastly, inhibition of PDE5A and PDE9A counter pathological remodeling of the heart and are both being pursued in clinical trials. Here we discuss recent research advances in each of these PDEs, their impact on the myocardium, and cardiac therapeutic potential. Address Correspondence: David A. Kass, M.D. Ross Research Building , Room 858 Johns Hopkins Medical Institutions 720 Rutland Avenue Baltimore, MD 21205 (410) 955-7153 dkass@jhmi.edu Copyright © 2019 Wolters Kluwer Health, Inc. All rights reserved.

CD137-CD137L signaling affects angiogenesis by mediating phenotypic conversion of macrophages Background: Angiogenesis in atherosclerotic plaque is an important factor causing plaque hemorrhage, vulnerability and rupture and different phenotypes of macrophages have different effects on angiogenesis. Our previous study has demonstrated CD137-CD137L signaling, a pair of inflammatory co-stimulatory molecules, can promote angiogenesis in atherosclerotic plaque. Therefore, we aimed to investigate whether this signaling could affect angiogenesis by regulating phenotypic transition of macrophages. Methods: Male mouse primary peritoneal macrophages were extracted by intraperitoneal injection of thioglycollate, and then flow cytometry was used to detect the expression of CD137. Flow cytometry, Western blotting, quantitative real-time PCR and enzyme-linked immunosorbent assay (ELISA) were used to assess the phenotypic changes of macrophages after different treatment. Mouse brain microvascular endothelial cells (bEnd.3) were co-cultured with macrophages and tube formation was assessed to examine angiogenesis. Results: We found that the number of junctions and branches of bEnd.3 were increased when CD137-CD137L signaling was activated, while such number was further increased when bEnd.3 were co-cultured with macrophages. Flow cytometry showed that CD137 was expressed on almost all primary peritoneal macrophages. The expression of CD86 was decreased in the agonist CD137L group and increased in the agonist CD137L + inhibitory anti-CD137 antibody group after adding the CD137 inhibitor. The expression of CD206 in each group exhibited opposite trend compared with CD86. Moreover, the expression of inducible nitric oxide synthase (iNOS) at the mRNA and protein levels was decreased after stimulating CD137-CD137L signaling, and such downward trend was reversed when CD137-CD137L signaling was inhibited. Furthermore, the expression of arginase-1 was opposite to that of iNOS. ELISA indicated that the content of interleukin-12 (IL-12) in the supernatant of macrophages in the agonist CD137L group was lower than that in the control group, and its content in the inhibited group was higher than that in the activated group. The change of interleukin-10 (IL-10) content in macrophage supernatant was opposite to that of IL-12. When AKT serine/threonine kinase 1 (Akt1) inhibitor was used to inhibit the phenotypic transformation of macrophages induced by CD137-CD137L, the number of junctions and branches formed by bEnd.3 was decreased compared with the co-culture group. Conclusions: These results indicated that CD137-CD137L signaling could promote angiogenesis by regulating phenotypic transition of macrophages of male mice. Corresponding author: E-mail:yanjinchuan@hotmail.com * These authors contributed equally to this work. This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially without permission from the journal. Copyright © 2019 Wolters Kluwer Health, Inc. All rights reserved.

Therapeutic implications of nitrite in hypertension Nitrite, an anion produced from the oxidative breakdown of nitric oxide (NO) has traditionally been viewed as an inert molecule. However, this dogma has been challenged with the findings that nitrite can be readily reduced to NO under pathological conditions, hence representing a physiologically relevant storage reservoir of NO either in the blood or tissues. Nitrite administration has been demonstrated to improve myocardial function in subjects with heart failure and to lower the blood pressure in hypertensive subjects. Thus, extensive amount of work has since been carried out to investigate the therapeutic potential of nitrite in treating cardiovascular diseases, especially hypertension. Studies done on several animal models of hypertension have demonstrated the efficacy of nitrite in preventing and ameliorating the pathological changes associated with the disease. This brief review of the current findings aims to re-evaluate the use of nitrite for the treatment of hypertension and in particular to highlight its role in improving endothelial function. Corresponding Author: Dharmani Devi Murugan, Department of Pharmacology, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia, Email address: dharmani79@um.edu.my Copyright © 2019 Wolters Kluwer Health, Inc. All rights reserved.

Perivascular adipose tissue modulation of neurogenic vasorelaxation of rat mesenteric arteries Perivascular sympathetic-sensory interactions have been shown to regulate calcitonin gene-related peptide (CGRP)-mediated vasodilation in rats. We investigated whether perivascular adipose tissue (PVAT) modulates the neurogenic vasorelaxation of isolated rat mesenteric arteries. Mesenteric arterial rings were prepared with or without PVAT (PVAT+ or PVAT−) and with either an intact or denuded endothelium (EC+ or EC-). The results of myography analysis revealed that vasocontraction to phenylephrine was highest in EC-PVAT-, lowest in EC+PVAT+, and intermediate in EC-PVAT+ and EC+PVAT-. Transmural nerve stimulation (TNS) induced the tetrodotoxin-sensitive relaxation of the phenylephrine-precontracted mesenteric arteries. However, nicotine induced minor relaxation in EC-PVAT+, while vasorelaxation was significantly enhanced in EC-PVAT-. Nicotine-induced vasorelaxation was insensitive to propranolol and also significantly lower in sympathetically-denervated and guanethidine-treated EC-PVAT-, while TNS-induced vasorelaxation persisted. In EC-PVAT- depleted of CGRP via capsaicin, nicotine- and TNS-induced vasorelaxation was almost absent. Lowering the pH of Krebs’ solution using HCl led to pH-dependent vasorelaxation that was sensitive to CGRP8-37. Furthermore, nicotine-induced relaxation of EC-PVAT-, which was not affected by leptin, was blocked by methyl palmitate. Methyl palmitate did not affect TNS- or HCl-induced vasorelaxation. These results suggest that PVAT plays a modulatory role in regulating sympathetic-sensory interaction-mediated CGRPergic vasorelaxation via the release of methyl palmitate. Corresponding Author: Shang-Jen Chang, MD, MS, Taipei Tzu Chi Hospital, New Taipei,, TAIWAN E-mail: changhh@livemail.tw, E-mail: urolyang@tzuchi.com.tw, E-mail: krissygnet@yahoo.com.tw Sources of funding: This work was supported by grants from Taipei Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation (TCRD-TPE-106-RT-6 and TCRD-TPE-107-51). Disclosures: No conflicts of interest, financial or otherwise, are declared by the authors. Copyright © 2019 Wolters Kluwer Health, Inc. All rights reserved.

Direct Oral Anticoagulant Use Following Transcatheter Aortic Valve Replacement: A Case Series Background: Use of an anticoagulant after transcatheter aortic valve replacement (TAVR) has been increasing in practice after noted leaflet thrombosis on dual antiplatelet therapy. As the use of anticoagulation increases so does the number of poor warfarin candidates or warfarin intolerant patients. While direct oral anticoagulant (DOAC) use is increasing for other indications there is a paucity of data for use post-TAVR. The objective of this case series is to add to the available evidence for patients who may require a DOAC following TAVR. Methods: A single-center, retrospective observational case series was conducted including adults 18 years of age and older who received a DOAC following TAVR between November 2008 and June 2018 at Mayo Clinic Hospital – Rochester. All patients were identified as part of the Society of Thoracic Surgeons database. Results: Twenty-one patients were identified as having received a DOAC post-TAVR. Median age was 83.5 years (IQR 77-87), with 71% males. Within this cohort, 20 patients (95.2%) had an alternative indication for anticoagulation of either atrial fibrillation or atrial flutter. Apixaban was prescribed in 66.7% of patients, followed by rivaroxaban (14.3%), dabigatran (9.5%), and edoxaban (4.8%). No thromboembolic events were reported. Three patients experienced a bleeding event, of which only 2 occurred in the 3 months immediately following TAVR. Conclusion: DOAC therapy after TAVR was generally safe and well tolerated. Taken in context of other retrospective studies this data suggests that the presence of valvular heart disease, specifically TAVR in this case, should not preclude the use of DOACs. Corresponding Author: Abby K. Hendricks, PharmD Mayo Clinic 200 First Street SW Rochester, MN 55905 Phone: 507-255-5732 Fax: 507-255-7556 Email: Hendricks.abby@mayo.edu Conflict of Interest: The authors declare that they have no conflicts of interest. Funding: No funding was provided to support this study. Copyright © 2019 Wolters Kluwer Health, Inc. All rights reserved.

Paul M. Vanhoutte, an Appreciation No abstract available

Inhibition of Endothelial Dysfunction by Dietary Flavonoids and Preventive Effects Against Cardiovascular Disease Cardiovascular disease (CVD), such as stroke, ischemic heart disease, and heart failure, accounts for many deaths, and its increasing incidence is a worldwide concern. Accumulating evidence suggests that the elevated risk of CVD caused by dysfunction of vascular endothelial cells and resultant arteriosclerosis can be mitigated by increased consumption of fruits and vegetables. These foods contain phytochemicals such as polyphenols and carotenoids, as well as dietary fiber. Flavonoids of the polyphenol class are found in vegetables, fruits, grains, bark, roots, stems, flowers, tea, and wine. Several studies have indicated that flavonoids reduce CVD mortality by inhibiting endothelial dysfunction. Flavonoids have a common carbon skeleton and are classified as flavonols, flavones, flavanols, flavanones, anthocyanidins, and isoflavones. In this review, we discuss recent progress in identifying the mechanisms by which dietary flavonoids improve vascular endothelial cell function. Further, we describe the beneficial role that these flavonoids may play in preventing CVD caused by endothelial dysfunction-related atherosclerosis. Corresponding author: Dr. Kazuo Yamagata Ph.D. Department of Food Bioscience and Biotechnology, College of Bioresource Science, Nihon University (UNBS), Fujisawa, Japan. Phone: +81-466-84-3986; Fax: +81-466-84-3986; E-mail: yamagata.kazuo@nihon-u.acj.jp Competing interests; The authors report no conflicts of interest. Funding; Not Consent for publication; Not applicable. Ethics approval and consent to participate; Not applicable. Copyright © 2019 Wolters Kluwer Health, Inc. All rights reserved.

Non-coding RNAs in atrial fibrillation: current status and prospect Atrial fibrillation (AF) is an important cause of cardiovascular morbidity and mortality. Current therapies for AF are ineffective, mainly due to incomplete understanding of the pathogenesis of AF. Atrial remodeling contributes to the occurrence and progression of AF, but molecular mechanisms underlying AF remain unclear. Non-coding RNAs, including microRNAs, long non-coding RNAs and circular RNAs, are now considered to play an important role in the pathophysiology of AF. In this review, we summarize recent evidence supporting the role of non-coding RNAs in AF and highlight their diagnostic and prognostic applications as potential biomarkers and therapeutic strategies. Corresponding author: Xiaosheng Hu, Department of Cardiology, The First Affiliated Hospital, Medical School of Zhejiang University, Zhejiang Province, 310000, China. Email: 1196017@zju.edu.cn Copyright © 2019 Wolters Kluwer Health, Inc. All rights reserved.

EFFECTS OF RIVAROXABAN ON PLATELET AGGREGATION Rivaroxaban is a direct oral anti-Factor Xa anticoagulant. It has recently been suggested that rivaroxaban may affect platelet function in vitro; however, little is known about the clinical impact of this likely antiplatelet effect and if this probable phenomenon is dose-dependent. Our aim was to determine whether rivaroxaban at four different doses inhibits direct platelet aggregation. We included adult patients of both genders and who were allocated to one of the following groups depending on the prescribed daily dose of rivaroxaban: 5, 10, 15, and 20 mg. In 80 patients (20 patients/group), the percentage of platelet aggregation was determined by means of platelet aggregometry tests before and after rivaroxaban use. Basal samples were obtained before starting rivaroxaban and 1 month after treatment, both 2 and 24 h after the last dose of the drug (12 h after in the case of rivaroxaban 5 mg). We used five platelet agonists: adenosine diphosphate, epinephrine, arachidonic acid, collagen, and thrombin. There were no significant changes in the percentage of platelet aggregation before and after rivaroxaban use independently of the dose administered and the agonist used. Our results clearly shown that rivaroxaban, even at a high dose, does not directly affect platelet aggregation. Address for correspondence: Abraham Majluf-Cruz, MD, PhD, FACP, Apartado Postal 12-1100 Mexico City, Mexico Tel/Fax: 0052-55-5574-5626 E-mail: abraham.majluf@imss.gob.mx Declarations of interest: none Copyright © 2019 Wolters Kluwer Health, Inc. All rights reserved.

Potential of the Cardiovascular Drug Levosimendan in the Management of Amyotrophic Lateral Sclerosis: Overview of a Working Hypothesis Levosimendan is a calcium sensitizer that promotes myocyte contractility through its calcium-dependent interaction with cardiac troponin C. Administered intravenously, it has been used for nearly two decades to treat acute and advanced heart failure and to support the heart function in various therapy settings characterized by low cardiac output. Effects of levosimendan on non-cardiac muscle suggest a possible new application in the treatment of people with amyotrophic lateral sclerosis (ALS), a neuromuscular disorder characterised by progressive weakness and eventual paralysis. Previous attempts to improve the muscle response in ALS patients and thereby maintain respiratory function and delay progression of disability have produced some mixed results. Continuing this line of investigation, levosimendan has been shown to enhance in vitro the contractility of diaphragm muscle fibres of non-ALS patients, and to improve in vivo diaphragm neuromuscular efficiency in heathy subjects. Possible positive effects on respiratory function in people with ALS was seen in an exploratory Phase 2 study, and a Phase 3 clinical trial is now underway to evaluate the potential benefit of an oral form of levosimendan on both respiratory and overall functions in patients with ALS. Here we will review the various known pharmacologic effects of levosimendan, considering their relevance to people living with ALS. Corresponding author: Piero Pollesello, Orion Pharma, P.O.Box 65 FIN-02101, Espoo, Finland, e-mail: piero.pollesello@orionpharma.com; tel.:+358509664191. Conflicts of interest: AA-C is a consultant for Orion Pharma, and has been Principal Investigator for clinical trials sponsored or supported by Orion Pharma. ZP has received lecture honoraria from Orion Pharma; LH received a grant from Orion Pharma to run a clinical trial; PP is an employee of Orion Pharma, where levosimendan was discovered and developed. This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially without permission from the journal. Copyright © 2019 Wolters Kluwer Health, Inc. All rights reserved.