Levosimendan attenuates pulmonary vascular remodeling

Electroacupuncture enhances cerebral blood perfusion by inhibiting HIF-1α in rat subarachnoid hemorrhage

OBJECTIVE

Cerebral blood perfusion (CBP) reduction is a prevalent complication following subarachnoid hemorrhage (SAH) in clinical practice, often associated with long-term cognitive impairment and prognosis. Electroacupuncture (EA), a widely utilized traditional Chinese therapy for central nervous system disorders, has demonstrated promising therapeutic effects. This study aims to investigate the therapeutic potential of EA in restoring CBP in SAH rats and to explore the mechanisms involving HIF-1α in this process.

METHODS

Rats were randomly assigned to one of five groups, including Sham, SAH, EA, EA + Saline, and EA + dimethyloxallyl glycine (DMOG) groups. EA treatment was administered for 10 min daily, while DMOG were intraperitoneally injected. Behavioral tests, cerebral blood flow monitoring, vascular thickness measurement, western blotting, and immunofluorescence staining were conducted to assess the therapeutic effects of EA on cerebral blood flow.

RESULTS

SAH resulted in elevated levels of HIF-1α, endothelin (ET), ICAM-1, P-SELECTIN, E-SELECTIN, and decreased level of eNOS in the brain. This led to cerebral vasospasm, decreased CBF, and cognitive deficits in the rat SAH model. EA intervention downregulated the expression of HIF-1α, ET, ICAM-1, P-SELECTIN, and E-SELECTIN, while increasing eNOS expression. This alleviated cerebral vasospasm, restored CBF, and improved cognitive function. However, the administration of the HIF-1α stabilizer (DMOG) counteracted the therapeutic effects of EA.

CONCLUSION

EA promotes the recovery of cerebral blood flow after SAH injury, attenuates cerebral vasospasm, and accelerates the recovery of cognitive dysfunction, and its mechanism of action may be related to the inhibition of the HIF-1α signaling pathway.

Levosimendan and Dobutamin Attenuate LPS-Induced Inflammation in Microglia by Inhibiting the NF-κB Pathway and NLRP3 Inflammasome Activation via Nrf2/HO-1 Signalling

Hypovolemic shock is a circulatory failure, due to a loss in the effective circulating blood volume, that causes tissue hypoperfusion and hypoxia. This condition stimulates reactive oxygen species (ROS) and pro-inflammatory cytokine production in different organs and also in the central nervous system (CNS). Levosimendan, a cardioprotective inodilator, and dobutamine, a β1-adrenergic agonist, are commonly used for the treatment of hypovolemic shock, thanks to their anti-inflammatory and antioxidant effects. For this reason, we aimed at investigating levosimendan and dobutamine's neuroprotective effects in an "in vitro" model of lipopolysaccharide (LPS)-induced neuroinflammation. Human microglial cells (HMC3) were challenged with LPS (0.1 µg/mL) to induce an inflammatory phenotype and then treated with levosimendan (10 µM) or dobutamine (50 µM) for 24 h. Levosimendan and dobutamine significantly reduced the ROS levels and markedly increased Nrf2 and HO-1 protein expression in LPS-challenged cells. Levosimendan and dobutamine also decreased p-NF-κB expression and turned off the NLRP3 inflammasome together with its downstream signals, caspase-1 and IL-1β. Moreover, a reduction in TNF-α and IL-6 expression and an increase in IL-10 levels in LPS-stimulated HMC3 cells was observed following treatment. In conclusion, levosimendan and dobutamine attenuated LPS-induced neuroinflammation through NF-κB pathway inhibition and NLRP3 inflammasome activation via Nrf2/HO-1 signalling, suggesting that these drugs could represent a promising therapeutic approach for the treatment of neuroinflammation consequent to hypovolemic shock.

Vasoactive Management of Pulmonary Hypertension and Ventricular Dysfunction in Neonates Following Complicated Monochorionic Twin Pregnancies: A Single-Center Experience

OBJECTIVES

Twins resulting from a complicated monochorionic (MC) twin pregnancy are at risk for postnatal evolution of pulmonary hypertension (PH) and cardiac dysfunction (CD). Both pathologies are important contributors to short- and long-term morbidity in these infants. The aim of the present retrospective single-center cohort study was to evaluate the need for vasoactive treatment for PH and CD in these neonates.

METHODOLOGY

In-born neonates following a complicated MC twin pregnancy admitted to the department of neonatology of the University Children's Hospital Bonn (UKB) between October 2019 and December 2023 were screened for study inclusion. Finally, 70 neonates were included in the final analysis, with 37 neonates subclassified as recipient twins (group A) and 33 neonates as donor twins (group B).

RESULTS

The overall PH incidence at day of life (DOL) 1 was 17% and decreased to 6% at DOL 7 (p = 0.013), with no PH findings at DOL 28. The overall incidence of CD was 56% at DOL 1 and decreased strongly until DOL 7 (10%, p = 0.015), with no diagnosis of CD at DOL 28. The use of dobutamine, norepinephrine, and vasopressin at DOL 1 until DOL 7 did not differ between the subgroups, whereas the dosing of milrinone was significantly higher in Group B at DOL 1 (p = 0.043). Inhaled nitric oxide (iNO) was used in 16% of the cohort, and a levosimendan therapy was administered in 34% of the neonates. One-third of the cohort was treated with oral beta blockers, and in 10%, an intravenous beta blockade (landiolol) was administered. The maximum levosimendan vasoactive-inotropic score (LVISmax) increased from DOL 1 (12.4 [3/27]) to DOL 2 (14.6 [1/68], p = 0.777), with a significant decrease thereafter as measured at DOL 7 (9.5 [2/30], p = 0.011).

CONCLUSION

Early PH and CD are frequent diagnoses in neonates following a complicated MC twin pregnancy, and an individualized vasoactive treatment strategy is required in the management of these infants.

Pressure Overload and Right Ventricular Failure: From Pathophysiology to Treatment

Right ventricular failure (RVF) is often caused by increased afterload and disrupted coupling between the right ventricle (RV) and the pulmonary arteries (PAs). After a phase of adaptive hypertrophy, pressure-overloaded RVs evolve towards maladaptive hypertrophy and finally ventricular dilatation, with reduced stroke volume and systemic congestion. In this article, we review the concept of RV-PA coupling, which depicts the interaction between RV contractility and afterload, as well as the invasive and non-invasive techniques for its assessment. The current principles of RVF management based on pathophysiology and underlying etiology are subsequently discussed. Treatment strategies remain a challenge and range from fluid management and afterload reduction in moderate RVF to vasopressor therapy, inotropic support and, occasionally, mechanical circulatory support in severe RVF.

Pulmonary Hypertension in Left Heart Diseases: Pathophysiology, Hemodynamic Assessment and Therapeutic Management

Pulmonary hypertension (PH) associated with left heart diseases (PH-LHD), also termed group 2 PH, represents the most common form of PH. It develops through the passive backward transmission of elevated left heart pressures in the setting of heart failure, either with preserved (HFpEF) or reduced (HFrEF) ejection fraction, which increases the pulsatile afterload of the right ventricle (RV) by reducing pulmonary artery (PA) compliance. In a subset of patients, progressive remodeling of the pulmonary circulation resulted in a pre-capillary phenotype of PH, with elevated pulmonary vascular resistance (PVR) further increasing the RV afterload, eventually leading to RV-PA uncoupling and RV failure. The primary therapeutic objective in PH-LHD is to reduce left-sided pressures through the appropriate use of diuretics and guideline-directed medical therapies for heart failure. When pulmonary vascular remodeling is established, targeted therapies aiming to reduce PVR are theoretically appealing. So far, such targeted therapies have mostly failed to show significant positive effects in patients with PH-LHD, in contrast to their proven efficacy in other forms of pre-capillary PH. Whether such therapies may benefit some specific subgroups of patients (HFrEF, HFpEF) with specific hemodynamic phenotypes (post- or pre-capillary PH) and various degrees of RV dysfunction still needs to be addressed.

The Effects of the Levosimendan Metabolites OR-1855 and OR-1896 on Endothelial Pro-Inflammatory Responses

The calcium sensitizer levosimendan is used for the treatment of acute decompensated heart failure. A small portion (4–7%) of levosimendan is metabolized to the pharmacologically active metabolite OR-1896 via the inactive intermediate OR-1855. In addition, levosimendan has been shown to exert positive effects on the endothelium in vitro antagonizing vascular dysfunction and inflammation. However, the function of the levosimendan metabolites within this context is still unknown. In this study, we thus investigated the impact of the metabolites OR-1896 and OR-1855 on endothelial inflammatory processes in vitro. We observed a reduction of IL-1β-dependent endothelial adhesion molecule ICAM-1 and VCAM-1 as well as interleukin (IL) -6 expression upon levosimendan treatment but not after treatment with OR-1855 or OR-1896, as assessed by western blotting, flow cytometry, and qRT-PCR. Instead, the metabolites impaired IL-1β-induced ROS formation via inactivation of the MAPK p38, ERK1/2, and JNK. Our results suggest that the levosimendan metabolites OR-1896 and OR-1855 have certain anti-inflammatory properties, partly other than levosimendan. Importantly, they additionally show that the intermediate metabolite OR-1855 does, in fact, have pharmacological effects in the endothelium. This is interesting, as the metabolites are responsible for the long-term therapeutic effects of levosimendan, and heart failure is associated with vascular dysfunction and inflammation.

Use of Levosimendan in Patients with Pulmonary Hypertension: What is the Current Evidence?

Pulmonary hypertension, defined as an increase in mean arterial pressure > 20 mmHg, is a chronic and progressive condition with high mortality and morbidity. Drug therapy of patients with pulmonary hypertension is based on the distinctive pathophysiologic aspect that characterizes the different groups. However, recently, levosimendan, a calcium-sensitizing agent with inotropic, pulmonary vasodilator, and cardioprotective properties, has been shown to be an effective and safe therapeutic strategy for patients with pulmonary arterial hypertension (in addition to specific drugs) and pulmonary hypertension associated with left heart disease (as possible treatment). This review provides a comprehensive overview of the current evidence on the use of levosimendan in patients with pulmonary hypertension.

Mechanisms of pulmonary vascular dysfunction in pulmonary hypertension and implications for novel therapies

Pulmonary hypertension (PH) is a serious disease characterized by various degrees of pulmonary vasoconstriction and progressive fibroproliferative remodeling and inflammation of the pulmonary arterioles that lead to increased pulmonary vascular resistance, right ventricular hypertrophy, and failure. Pulmonary vascular tone is regulated by a balance between vasoconstrictor and vasodilator mediators, and a shift in this balance to vasoconstriction is an important component of PH pathology, Therefore, the mainstay of current pharmacological therapies centers on pulmonary vasodilation methodologies that either enhance vasodilator mechanisms such as the NO-cGMP and prostacyclin-cAMP pathways and/or inhibit vasoconstrictor mechanisms such as the endothelin-1, cytosolic Ca2+, and Rho-kinase pathways. However, in addition to the increased vascular tone, many patients have a "fixed" component in their disease that involves altered biology of various cells in the pulmonary vascular wall, excessive pulmonary artery remodeling, and perivascular fibrosis and inflammation. Pulmonary arterial smooth muscle cell (PASMC) phenotypic switch from a contractile to a synthetic and proliferative phenotype is an important factor in pulmonary artery remodeling. Although current vasodilator therapies also have some antiproliferative effects on PASMCs, they are not universally successful in halting PH progression and increasing survival. Mild acidification and other novel approaches that aim to reverse the resident pulmonary vascular pathology and structural remodeling and restore a contractile PASMC phenotype could ameliorate vascular remodeling and enhance the responsiveness of PH to vasodilator therapies.

Role of Ion Channel Remodeling in Endothelial Dysfunction Induced by Pulmonary Arterial Hypertension

Endothelial dysfunction is a key player in advancing vascular pathology in pulmonary arterial hypertension (PAH), a disease essentially characterized by intense remodeling of the pulmonary vasculature, vasoconstriction, endothelial dysfunction, inflammation, oxidative stress, and thrombosis in situ. These vascular features culminate in an increase in pulmonary vascular resistance, subsequent right heart failure, and premature death. Over the past years, there has been a great development in our understanding of pulmonary endothelial biology related to the genetic and molecular mechanisms that modulate the endothelial response to direct or indirect injury and how their dysregulation can promote PAH pathogenesis. Ion channels are key regulators of vasoconstriction and proliferative/apoptotic phenotypes; however, they are poorly studied at the endothelial level. The current review will describe and categorize different expression, functions, regulation, and remodeling of endothelial ion channels (K+, Ca2+, Na+, and Cl− channels) in PAH. We will focus on the potential pathogenic role of ion channel deregulation in the onset and progression of endothelial dysfunction during the development of PAH and its potential therapeutic role.

Cardiac Ischemia On-a-Chip: Antiarrhythmic Effect of Levosimendan on Ischemic Human-Induced Pluripotent Stem Cell-Derived Cardiomyocytes

Ischemic heart disease (IHD) is one of the leading causes of mortality worldwide. Preserving functionality and preventing arrhythmias of the heart are key principles in the management of patients with IHD. Levosimendan, a unique calcium (Ca2+) enhancer with inotropic activity, has been introduced into clinical usage for heart failure treatment. Human-induced pluripotent cell-derived cardiomyocytes (hiPSC-CMs) offer an opportunity to better understand the pathophysiological mechanisms of the disease as well as to serve as a platform for drug screening. Here, we developed an in vitro IHD model using hiPSC-CMs in hypoxic conditions and defined the effects of the subsequent hypoxic stress on CMs functionality. Furthermore, the effect of levosimendan on hiPSC-CMs functionality was evaluated during and after hypoxic stress. The morphology, contractile, Ca2+-handling, and gene expression properties of hiPSC-CMs were investigated in response to hypoxia. Hypoxia resulted in significant cardiac arrhythmia and decreased Ca2+ transient amplitude. In addition, disorganization of sarcomere structure was observed after hypoxia induction. Interestingly, levosimendan presented significant antiarrhythmic properties, as the arrhythmia was abolished or markedly reduced with levosimendan treatment either during or after the hypoxic stress. Moreover, levosimendan presented significant protection from the sarcomere alterations induced by hypoxia. In conclusion, this chip model appears to be a suitable preclinical representation of IHD. With this hypoxia platform, detailed knowledge of the disease pathophysiology can be obtained. The antiarrhythmic effect of levosimendan was clearly observed, suggesting a possible new clinical use for the drug.

Pretreatment with the active fraction of Rhodiola tangutica (Maxim.) S.H. Fu rescues hypoxia-induced potassium channel inhibition in rat pulmonary artery smooth muscle cells

ETHNOPHARMACOLOGICAL RELEVANCE

Previous studies have shown that the active fraction of Rhodiola tangutica (Maxim.) S.H. Fu (ACRT) dilates pulmonary arteries and thwarts pulmonary artery remodelling. The dilatation effect of ACRT on pulmonary artery vascular rings could be reduced by potassium (K⁺) channel blockers. However the exact mechanisms of ACRT on ion channels are still unclear.

AIM OF THE STUDY

This study aimed to investigate whether the effect of ACRT on K⁺ channels inhibits cell proliferation after pulmonary artery smooth muscle cells (PASMCs) are exposed to hypoxia.

MATERIALS AND METHODS

The whole-cell patch-clamp method was used to clarify the effect of ACRT on the K⁺ current (I_K) of rat PASMCs exposed to hypoxia. The mRNA and protein expression levels were detected using real-time quantitative polymerase chain reaction (RT-qPCR) and western blotting, respectively. The intracellular calcium (Ca²⁺) concentration ([Ca²⁺]_i) values in rat PASMCs were detected by laser scanning confocal microscopy. The cell cycle and cell proliferation were assessed using flow cytometry analysis and CCK-8 and EdU assays.

RESULTS

ACRT pretreatment alleviated the inhibition of I_K induced by hypoxia in rat PASMCs. Compared with hypoxia, ACRT upregulated voltage-dependent K⁺ channel (K_v) 1.5 and big-conductance calcium-activated K⁺ channel (BK_Ca) mRNA and protein expression and downregulated voltage-dependent Ca²⁺ channel (Ca_v) 1.2 mRNA and protein expression. ACRT decreased [Ca²⁺]_i, inhibited the promotion of cyclin D1 and proliferating cell nuclear antigen (PCNA) expression, and prevented the proliferation of rat PASMCs exposed to hypoxia.

CONCLUSION

In conclusion, the present study demonstrated that ACRT plays a key role in restoring ion channel function and then inhibiting the proliferation of PASMCs under hypoxia, ACRT has preventive and therapeutic potential in hypoxic pulmonary hypertension.

Does the cardiovascular drug levosimendan prevent iodinated contrast medium nephrotoxicity with glycerol aggravation in rats?

Background

We investigated whether levosimendan prevents contrast medium nephrotoxicity with glycerol aggravation in rats.

Methods

Forty-eight Wistar albino rats were assigned to eight groups (n = 6 × 8). No medication was administered to group I (controls); glycerol (intramuscular injection of 25% glycerol, 10 mL/kg) group II; intravenous iohexol 10 mL/kg to group III; glycerol and iohexol to group IV; iohexol and intraperitoneal levosimendan 0.25 mg/kg to group V; glycerol, iohexol, and levosimendan 0.25 mg/kg to group VI; iohexol and levosimendan 0.5 mg/kg to group VII; and glycerol, iohexol, and levosimendan 0.5 mg/kg to group VIII. One-day water withdrawal and glycerol injection prompted renal damage; iohexol encouraged nephrotoxicity; levosimendan was administered 30 min after glycerol injection and continued on days 2, 3, and 4. The experiment was completed on day 5. Serum blood urea nitrogen (BUN) and creatinine levels, superoxide dismutase (SOD) activity, glutathione (GSH), malondialdehyde (MDA) levels, tumour necrosis factor-α (TNF-α), nuclear factor kappa ß (NFK-ß), interleukin 6 (IL-6), and histopathological marks were assessed. One-way analysis of variance and Duncan’s multiple comparison tests were used.

Results

Levosimendan changed serum BUN (p = 0.012) and creatinine (p = 0.018), SOD (p = 0.026), GSH (p = 0.012), and MDA (p = 0.011). Levosimendan significantly downregulated TNF-α (p = 0.022), NFK-ß (p = 0.008), and IL-6 (p = 0.033). Histopathological marks of hyaline and haemorrhagic cast were improved in levosimendan-injected groups.

Conclusion

Levosimendan showed nephroprotective properties due to its vasodilator, oxidative distress decreasing and inflammatory cytokine preventing belongings.

Levosimendan-induced venodilation is mediated by opening of potassium channels

Unique vascular responses adhere to the cardiovascular efficacy of the inodilator levosimendan. In particular, selective venodilation appears to explain its clinical benefit during pulmonary hypertension complicated by heart failure with preserved ejection fraction. Vasodilators increase vessel diameter in various parts of the vascular system to different degrees and thereby influence blood pressure, its distribution, and organ perfusion depending on their mechanisms of action. Levosimendan and its long‐lived active metabolite OR‐1896 mobilize a set of vasodilatory mechanisms, that is, the opening of the ATP‐sensitive K⁺ channels and other K⁺ channels on top of a highly selective inhibition of the phosphodiesterase III enzyme. A vessel‐specific combination of the above vasodilator mechanisms—in concert with cardiac effects and cardiovascular reflex regulations—illustrates the pharmacological profile of levosimendan in various cardiovascular disorders. While levosimendan has been known to be an inotrope, its properties as an activator of ATP‐sensitive K⁺ channels have gone largely ignored with respect to clinical applications. Here, we provide a summary of what is known about the ATP‐sensitive K⁺ channel properties in preclinical studies and now for the first time, its ATP‐sensitive K⁺ channel properties in a clinical trial.

Optimization with levosimendan improves outcomes after left ventricular assist device implantation

OBJECTIVES

The aim of this study was to examine the haemodynamic effects of preoperative levosimendan infusion in patients who underwent left ventricular assist device implantation and evaluate the prognoses.

METHODS

Between May 2013 and October 2018, 85 adult patients who underwent left ventricular assist device implantation were included; 44 and 41 patients suffered from dilated cardiomyopathy and ischaemic cardiomyopathy, respectively. Patients were divided into 2 groups: group A (58 patients) included those who received levosimendan infusion in addition to other inotropes and group B (27 patients) included those who received inotropic agents other than levosimendan. Levosimendan infusion was started at a dose of 0.1 µg⋅kg-1⋅min-1 for a maximum of 48 h without a bolus. The primary outcome was early right ventricular failure (RVF). The secondary outcomes were in-hospital mortality, need for right ventricular assist device, late RVF and recovery of end-organ functions. The safety end points of levosimendan included hypotension, atrial fibrillation, ventricular tachycardia or fibrillation and resuscitated cardiac arrest.

RESULTS

Patient characteristics were similar in both groups. No significant differences between groups were observed in the rates of early mortality, RVF, need for right ventricular assist device, cardiopulmonary bypass time and intensive care unit stay. Survival rates at 30 days, 1 year and 3 years and freedom from late RVF were similar between the groups. Administration of levosimendan was safe, generally well-tolerated and not interrupted because of side effects.

CONCLUSIONS

Levosimendan therapy was well-tolerated in patients who received permanent left ventricular assist devices. Combined preoperative therapy with inotropes and levosimendan significantly improves end-organ functions.

Potassium (K+) channels in the pulmonary vasculature: Implications in pulmonary hypertension Physiological, pathophysiological and pharmacological regulation

The large K⁺ channel functional diversity in the pulmonary vasculature results from the multitude of genes expressed encoding K⁺ channels, alternative RNA splicing, the post-transcriptional modifications, the presence of homomeric or heteromeric assemblies of the pore-forming α-subunits and the existence of accessory β-subunits modulating the functional properties of the channel. K⁺ channels can also be regulated at multiple levels by different factors controlling channel activity, trafficking, recycling and degradation. The activity of these channels is the primary determinant of membrane potential (Em) in pulmonary artery smooth muscle cells (PASMC), providing an essential regulatory mechanism to dilate or contract pulmonary arteries (PA). K⁺ channels are also expressed in pulmonary artery endothelial cells (PAEC) where they control resting Em, Ca²⁺ entry and the production of different vasoactive factors. The activity of K⁺ channels is also important in regulating the population and phenotype of PASMC in the pulmonary vasculature, since they are involved in cell apoptosis, survival and proliferation. Notably, K⁺ channels play a major role in the development of pulmonary hypertension (PH). Impaired K⁺ channel activity in PH results from: 1) loss of function mutations, 2) downregulation of its expression, which involves transcription factors and microRNAs, or 3) decreased channel current as a result of increased vasoactive factors (e.g., hypoxia, 5-HT, endothelin-1 or thromboxane), exposure to drugs with channel-blocking properties, or by a reduction in factors that positively regulate K⁺ channel activity (e.g., NO and prostacyclin). Restoring K⁺ channel expression, its intracellular trafficking and the channel activity is an attractive therapeutic strategy in PH.

Potential of the Cardiovascular Drug Levosimendan in the Management of Amyotrophic Lateral Sclerosis: An 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 2 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 noncardiac muscle suggest a possible new application in the treatment of people with amyotrophic lateral sclerosis (ALS), a neuromuscular disorder characterized 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 the diaphragm muscle fibers of non-ALS patients and to improve in vivo diaphragm neuromuscular efficiency in healthy subjects. Possible positive effects on respiratory function in people with ALS were 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.

Levosimendan reduces segmental pulmonary vascular resistance in isolated perfused rat lungs and relaxes human pulmonary vessels

INTRODUCTION

Levosimendan is approved for acute heart failure. Within this context, pulmonary hypertension represents a frequent co-morbidity. Hence, the effects of levosimendan on segmental pulmonary vascular resistance (PVR) are relevant. So far, this issue has been not studied. Beyond that the relaxant effects of levosimendan in human pulmonary vessel are unknown. We addressed these topics in rats' isolated perfused lungs (IPL) and human precision-cut lung slices (PCLS).

MATERIAL AND METHODS

In IPL, levosimendan (10 μM) was perfused in untreated and endothelin-1 pre-contracted lungs. The pulmonary arterial pressure (PPA) was continuously recorded and the capillary pressure (Pcap) was determined by the double-occlusion method. Thereafter, segmental PVR, expressed as precapillary (Rpre) and postcapillary resistance (Rpost) and PVR were calculated. Human PCLS were prepared from patients undergoing lobectomy. Levosimendan-induced relaxation was studied in naïve and endothelin-1 pre-contracted PAs and PVs. In endothelin-1 pre-contracted PAs, the role of K+-channels was studied by inhibition of KATP-channels (glibenclamide), BKCa2+-channels (iberiotoxin) and Kv-channels (4-aminopyridine). All changes of the vascular tone were measured by videomicroscopy. In addition, the increase of cAMP/GMP due to levosimendan was measured by ELISA.

RESULTS

Levosimendan did not relax untreated lungs or naïve PAs and PVs. In IPL, levosimendan attenuated the endothelin-1 induced increase of PPA, PVR, Rpre and Rpost. In human PCLS, levosimendan relaxed pre-contracted PAs or PVs to 137% or 127%, respectively. In pre-contracted PAs, the relaxant effect of levosimendan was reduced, if KATP- and Kv-channels were inhibited. Further, levosimendan increased cGMP in PAs/PVs, but cAMP only in PVs.

DISCUSSION

Levosimendan reduces rats' segmental PVR and relaxes human PAs or PVs, if the pulmonary vascular tone is enhanced by endothelin-1. Regarding levosimendan-induced relaxation, the activation of KATP- and Kv-channels is of impact, as well as the formation of cAMP and cGMP. In conclusion, our results suggest that levosimendan improves pulmonary haemodynamics, if PVR is increased as it is the case in pulmonary hypertension.

TMEM16A regulates the cell cycle of pulmonary artery smooth muscle cells in high-flow-induced pulmonary arterial hypertension rat model

High-flow-induced pulmonary arterial hypertension (PAH) has attained global notoriety, the mechanism of which remains elusive. The present study investigated the regulation of Anoctamin-1, also known as transmembrane member 16A (TMEM16A), in the cell cycle progression of pulmonary artery smooth muscle cells (PASMCs) from a PAH rat model induced by high pulmonary blood flow. A total of 30 Sprague-Dawley rats were randomly assigned into control, sham and shunt groups. A rat model of high pulmonary blood flow-induced PAH was established by surgery using abdominal aorta-inferior vena cava fistula. Right ventricular pressure, right ventricular hypertrophy index and pulmonary arteriole structural remodeling were assessed 11 weeks following operation. The cell cycle statuses of PASMCs was assessed via flow cytometry, whereas western blot analysis was performed to measure the expression of cyclin D1, CDK2, p27KIP and cyclin E in primary PASMCs isolated from rats. The expression of cyclin E and cyclin D1 was revealed to be increased in the shunt group compared with the control group, which was accompanied with an increased expression of TMEM16A in the shunt group. Changes in the ratio of PASMCs in the G0/G1, S and G2/M phases of cycle induced by PAH were reversed by TMEM16A knockdown. The expression of cyclin E and cyclin D1 in the shunt group was significantly higher compared with the control group in vitro, which was reversed by TMEM16A-siRNA transfection. In conclusion, TMEM16A may be involved in high pulmonary blood flow-induced PAH by regulating PASMC cell cycle progression.

Grape seed procyanidin suppresses inflammation in cigarette smoke-exposed pulmonary arterial hypertension rats by the PPAR-γ/COX-2 pathway

BACKGROUND AND AIM

Pulmonary arterial hypertension (PAH) is characterized by pulmonary vascular remodeling, which is mainly caused by inflammation. Inhibiting inflammation can relieve PAH. Grape seed procyanidin (GSP) possesses remarkable anti-inflammatory property and vascular protective function. In this experiment, we verified the anti-inflammatory property of GSP in cigarette smoke-exposed PAH rats and revealed its molecular mechanism.

METHODS AND RESULTS

In vivo, 45 Sprague Dawley (SD) rats were divided into 5 groups randomly, treated with normoxia/cigarette smoke (CS)/GSP + CS/CS + solvent/GSP. After GSP + CS administration, a decrease in mPAP, PVR, RVHI, WT%, and WA% was detected in the rats as compared to those treated with CS. In vitro, the proliferation of pulmonary arterial smooth muscle cells (PASMCs) caused by cigarette smoke extract (CSE) was effectively attenuated with GSP + CSE administration. Furthermore, GSP significantly increased the expression of peroxisome proliferator-activated receptor γ (PPAR-γ) together with the lowered expression level of cyclooxygenase 2 (COX-2) in PASMCs co-incubated with CSE.

CONCLUSION

These findings indicate that GSP ameliorates inflammation by the PPAR-γ/COX-2 pathway and finally inhibits the proliferation of PASMCs, which leads to pulmonary vascular remodeling.

Effects of Levosimendan on Inflammation and Oxidative Stress Pathways in a Lipopolysaccharide-Stimulated Human Endothelial Cell Model

Levosimendan is a myocardial Ca²⁺ sensitizer and opener of ATP-dependent potassium channels with inotropic, vasodilating, and cardioprotective properties. It was originally developed for the treatment of acute decompensated heart failure, but its complex mechanism of action means that it could also play a role in organ protection in response to infection. Using an in vitro approach, we explored whether levosimendan administration influenced cell responses to lipopolysaccharide (LPS). Primary human umbilical vein endothelial cells were stimulated with 1 µg/ml LPS from Escherichia coli (E. coli). Cells were treated with levosimendan at 0, 0.1, 1, or 10 µM 3 hr later. Samples were taken 24 hr after treatment to measure cell necrosis, apoptosis, pro-inflammatory mediators (interleukin 6 [IL-6] and toll-like receptor 4 [TLR4]), and oxidative stress (total reactive oxygen species/reactive nitrogen species [ROS/RNS]). Levosimendan at 1 and 10 µM protected against LPS-induced endothelial cell death and reduced TLR4 expression (p < .05). All doses reduced levels of IL-6 and ROS/RNS (p < .05). Findings suggest that levosimendan may exert protective effects against endothelial cell death in this model via attenuation of inflammation and oxidative stress pathways. Future studies might explore the potential beneficial role of levosimendan in modulating molecular mechanisms triggered by infections.

Potassium channels in vascular smooth muscle: a pathophysiological and pharmacological perspective

Potassium (K⁺ ) ion channel activity is an important determinant of vascular tone by regulating cell membrane potential (MP). Activation of K⁺ channels leads to membrane hyperpolarization and subsequently vasodilatation, while inhibition of the channels causes membrane depolarization and then vasoconstriction. So far five distinct types of K⁺ channels have been identified in vascular smooth muscle cells (VSMCs): Ca⁺² -activated K⁺ channels (BK_{C a} ), voltage-dependent K⁺ channels (K_V ), ATP-sensitive K⁺ channels (K_ATP ), inward rectifier K⁺ channels (K_ir ), and tandem two-pore K⁺ channels (K₂ P). The activity and expression of vascular K⁺ channels are changed during major vascular diseases such as hypertension, pulmonary hypertension, hypercholesterolemia, atherosclerosis, and diabetes mellitus. The defective function of K⁺ channels is commonly associated with impaired vascular responses and is likely to become as a result of changes in K⁺ channels during vascular diseases. Increased K⁺ channel function and expression may also help to compensate for increased abnormal vascular tone. There are many pharmacological and genotypic studies which were carried out on the subtypes of K⁺ channels expressed in variable amounts in different vascular beds. Modulation of K⁺ channel activity by molecular approaches and selective drug development may be a novel treatment modality for vascular dysfunction in the future. This review presents the basic properties, physiological functions, pathophysiological, and pharmacological roles of the five major classes of K⁺ channels that have been determined in VSMCs.

Levosimendan in Acute and Advanced Heart Failure: An Appraisal of the Clinical Database and Evaluation of Its Therapeutic Applications

The use of inotropes for correcting hemodynamic dysfunction in patients with congestive heart failure has been described over many decades. However, negative or insufficient data have been collected regarding the effects of cardiac glycosides, catecholamines, and phosphodiesterase inhibitors on quality of life and survival. More recently, the calcium sensitizer and potassium channel-opener levosimendan has been proposed as a safer inodilator than traditional agents in some heart failure settings, such as advanced heart failure. At the 2017 annual congress of the Heart Failure Association of the European Society of Cardiology (Paris, April 30-May 2), a series of tutorials delivered by lecturers from 8 European countries examined how to use levosimendan safely and effectively in acute and advanced heart failure. The proceedings of those tutorials have been collated in this review to provide an expert perspective on the optimized use of levosimendan in those settings.

Ion Channels in Pulmonary Hypertension: A Therapeutic Interest?

Pulmonary arterial hypertension (PAH) is a multifactorial and severe disease without curative therapies. PAH pathobiology involves altered pulmonary arterial tone, endothelial dysfunction, distal pulmonary vessel remodeling, and inflammation, which could all depend on ion channel activities (K⁺, Ca²⁺, Na⁺ and Cl^-). This review focuses on ion channels in the pulmonary vasculature and discusses their pathophysiological contribution to PAH as well as their therapeutic potential in PAH.

Levosimendan in pulmonary hypertension and right heart failure

Pulmonary hypertension is a multifactorial disease with a high morbidity and mortality. Right ventricular function is the most important predictor of morbidity and mortality in patients suffering from pulmonary hypertension, but currently there are no approved treatments directly supporting the failing right ventricle. Levosimendan is a calcium sensitizing agent with inotropic, pulmonary vasodilatory, and cardioprotective properties. Given its pharmacodynamic profile, levosimendan could be a potential novel agent for the treatment of right ventricular failure caused by pulmonary hypertension. The aim of this review is to provide an overview of the current knowledge on the effects of levosimendan in pulmonary hypertension and right heart failure.

PDGF-BB regulates the pulmonary vascular tone: impact of prostaglandins, calcium, MAPK- and PI3K/AKT/mTOR signalling and actin polymerisation in pulmonary veins of guinea pigs

Background

Platelet-derived growth factor (PDGF)-BB and its receptor PDGFR are highly expressed in pulmonary hypertension (PH) and mediate proliferation. Recently, we showed that PDGF-BB contracts pulmonary veins (PVs) and that this contraction is prevented by inhibition of PDGFR-β (imatinib/SU6668). Here, we studied PDGF-BB-induced contraction and downstream-signalling in isolated perfused lungs (IPL) and precision-cut lung slices (PCLS) of guinea pigs (GPs).

Methods

In IPLs, PDGF-BB was perfused after or without pre-treatment with imatinib (perfused/nebulised), the effects on the pulmonary arterial pressure (P_PA), the left atrial pressure (P_LA) and the capillary pressure (P_cap) were studied and the precapillary (R_pre) and postcapillary resistance (R_post) were calculated. Perfusate samples were analysed (ELISA) to detect the PDGF-BB-induced release of prostaglandin metabolites (TXA₂/PGI₂). In PCLS, the contractile effect of PDGF-BB was evaluated in pulmonary arteries (PAs) and PVs. In PVs, PDGF-BB-induced contraction was studied after inhibition of PDGFR-α/β, L-Type Ca²⁺-channels, ROCK/PKC, prostaglandin receptors, MAP2K, p38-MAPK, PI3K-α/γ, AKT/PKB, actin polymerisation, adenyl cyclase and NO. Changes of the vascular tone were measured by videomicroscopy. In PVs, intracellular cAMP was measured by ELISA.

Results

In IPLs, PDGF-BB increased P_PA, P_cap and R_post. In contrast, PDGF-BB had no effect if lungs were pre-treated with imatinib (perfused/nebulised). In PCLS, PDGF-BB significantly contracted PVs/PAs which was blocked by the PDGFR-β antagonist SU6668. In PVs, inhibition of actin polymerisation and inhibition of L-Type Ca²⁺-channels reduced PDGF-BB-induced contraction, whereas inhibition of ROCK/PKC had no effect. Blocking of EP_1/3- and TP-receptors or inhibition of MAP2K-, p38-MAPK-, PI3K-α/γ- and AKT/PKB-signalling prevented PDGF-BB-induced contraction, whereas inhibition of EP₄ only slightly reduced it. Accordingly, PDGF-BB increased TXA₂ in the perfusate, whereas PGI₂ was increased in all groups after 120 min and inhibition of IP-receptors did not enhance PDGF-BB-induced contraction. Moreover, PDGF-BB increased cAMP in PVs and inhibition of adenyl cyclase enhanced PDGF-BB-induced contraction, whereas inhibition of NO-formation only slightly increased it.

Conclusions

PDGF-BB/PDGFR regulates the pulmonary vascular tone by the generation of prostaglandins, the increase of calcium, the activation of MAPK- or PI3K/AKT/mTOR signalling and actin remodelling. More insights in PDGF-BB downstream-signalling may contribute to develop new therapeutics for PH.

Cardioprotective and Anti-Aggregatory Effects of Levosimendan on Isoproterenol-Induced Myocardial Injury in High-Fat-Fed Rats Involves Modulation of PI3K/Akt/mTOR Signaling Pathway and Inhibition of Apoptosis

Hyperlipidemia and hypercoagulability states are linked with the increased risks of myocardial infarction (MI). Levosimendan has vasorelaxant and anti-aggregatory properties. The present study evaluated the anti-aggregatory and cardioprotective effects of levosimendan versus cilostazol in high-fat diet (HFD)-fed rats subjected to isoproterenol-induced MI. Rats were assigned to normal, HFD, HFD + isoproterenol, HFD + isoproterenol + cilostazol, and HFD + isoproterenol + levosimendan. The present study investigated the anti-aggregatory effect of both levosimendan and cilostazol and revealed that both drugs attenuated the severity of platelet aggregation. Moreover, both levosimendan and cilostazol revealed effectiveness in attenuating the severity of HFD/isoproterenol-induced myocardial injury as revealed by electrocardiogram signs, apoptotic markers, and histopathological score via counteracting the oxidative stress burden, increments in the expression of inflammatory mediators, and modulating nuclear factor kappa-B (NF-κB) and phosphatidylinositide 3-kinases (PI3K)/protein kinase B (Akt)/ mechanistic target of rapamycin (mTOR) pathway. It was obvious that levosimendan offered more cardioprotective properties than cilostazol. The study showed the relations between hyperlipedemia, hyperaggregability state, and myocardial injury with the modulation of NF-κB and PI3K/Akt/mTOR pathway.

Efficacy and safety of levosimendan in patients with acute right heart failure: A meta-analysis

AIMS

Right heart failure (RHF), which is caused by a variety of heart and lung diseases, has a high morbidity and mortality rate. Levosimendan is a cardiac inotropic drug and vasodilator. The effect of levosimendan on RHF remains unclear. We sought to evaluate the efficacy and safety of levosimendan in patients with acute RHF.

MATERIALS AND METHODS

We systematically searched PubMed, Cochrane Library, EMBASE, and ClinicalTrials.gov to identify studies reporting the efficacy and safety of levosimendan for the treatment of RHF.

KEY FINDINGS

Ten trials, including 359 participants from 6 RCTs and 4 self-controlled trials, were evaluated. In the 6 RCTs, we found that patients treated with levosimendan for 24h showed a significant increase in tricuspid annular plane systolic excursion [1.53; 95% CI (0.54, 2.53); P=0.002] and ejection fraction [3.59; 95% CI (1.21, 5.98); P=0.003] as well as a significant reduction in systolic pulmonary artery pressure [-6.15; 95% CI (-9.29, -3.02); P=0.0001] and pulmonary vascular resistance [-39.48; 95% CI (-65.59, -13.38); P=0.003], whereas changes in mean pulmonary pressure were nonsignificant. Adverse events did not significantly differ between the two groups.

SIGNIFICANCE

Our study shows that levosimendan exhibits short-term efficacy for treating RHF in patients with a variety of heart and lung diseases. Additional strict multicentre RCTs with long follow-up times and large sample sizes are required to further validate the efficacy and safety of this treatment.

Dose–Response Head-to-Head Comparison of Inodilators Dobutamine, Milrinone, and Levosimendan in Chronic Experimental Pulmonary Hypertension

The choice of inodilator drug in the acute management of patients with pulmonary hypertension (PH) having right ventricular (RV) failure remains unsettled and challenging. Comprehensive experimental evaluations may provide further insight and fundamental translational research clues to support inodilator selection and clinical trial design. Our aim was to compare acute dose–response hemodynamic effects of inodilators dobutamine (DOB), milrinone (MIL), and levosimendan (LEV) in chronic experimental PH. Seven-week-old male Wistar rats were randomly injected with 60 mg·kg−1 monocrotaline (MCT) or vehicle (Ctrl, n = 7) and underwent systemic and pulmonary artery (PA) pressure and RV pressure–volume (PV) hemodynamic evaluation under halogenate anesthesia 24 to 30 days after injection. The MCT-injected animals (n = 7 each) randomly received dose–response infusions of DOB (1, 3, 6 and 12 μg·kg−1·min−1), MIL (MIL: 1, 3, 6 and 12 μg·kg−1·min−1), or LEV (0.3, 0.6, 1.2 and 2.4 μg·kg−1·min−1). Load-independent indexes were obtained by inferior vena cava occlusion at baseline and after the last dose. All inodilators increased RV ejection fraction, preload recruitable stroke work, and ventricular–vascular coupling without jeopardizing perfusion pressure. Dobutamine raised heart rate and PA pressure. Only LEV increased cardiac index and decreased PA elastance and pulmonary vascular resistance (PVR). Moreover, only LEV downward-shifted the end-diastolic PV relationship, thereby improving RV compliance. Adding sildenafil to LEV further decreased PVR. Levosimendan had beneficial acute systolic and diastolic functional effects in experimental chronic PH and RV afterload compared to DOB and MIL. It should be further tested in clinical trials enrolling patients with PH in the perioperative and critical care settings.

Anti-thrombotic and pro-fibrinolytic effects of levosimendan in human endothelial cells in vitro

AIMS

Levosimendan is an inodilator for the treatment of acute decompensated heart failure (HF). Data from clinical studies suggest that levosimendan is particularly effective in HF due to myocardial infarction. After acute revascularization, no reflow-phenomenon is a common complication that may lead to pump failure and cardiogenic shock. Our aim was to examine whether levosimendan interferes with the pro-thrombotic phenotype of activated endothelial cells in vitro.

METHODS

Human heart microvascular endothelial cells (HHMEC) and human umbilical vein endothelial cells (HUVEC) were treated with interleukin-1β (IL-1β) (200U/mL) or thrombin (5U/mL) and co-treated with or without levosimendan (0.1-10μM) for 2-24h. In addition, flow experiments were performed. Effects on plasminogen activator inhibitor-1 (PAI-1) and tissue factor (TF) expression and activity were measured by rt-PCR, specific ELISA and flow cytometry.

RESULTS

Treatment with IL-1β or thrombin significantly increased the expression of PAI-1 and TF in endothelial cells. Co-treatment with levosimendan strongly attenuated the effects of IL-1β and thrombin on PAI-1 and TF mRNA by up to 50% and 45%, in a dose- and time-dependent manner. Similar results were obtained under flow conditions. Furthermore, co-treatment with levosimendan dampened the antigen production of PAI-1 and the surface expression of TF by 35% and 45%, respectively. Additionally, levosimendan diminished both TF and PAI-1 activity.

CONCLUSION

Levosimendan down-regulates the expression of the pro-thrombotic and anti-fibrinolytic biomolecules TF and PAI-1 in activated human endothelial cells. Our findings may, at least in part, explain some of the beneficial effects of levosimendan after myocardial reperfusion.

Imatinib relaxes the pulmonary venous bed of guinea pigs

Background

Recently, the IMPRES study revealed that systemic imatinib improves exercise capacity in patients with advanced pulmonary arterial hypertension. Imatinib blocks the tyrosine kinase activity of the platelet-derived growth factor (PDGF)-receptor (PDGFR), acts antiproliferative and relaxes pulmonary arteries. However so far, the relaxant effects of imatinib on pulmonary veins (PVs) and on the postcapillary resistance are unknown, although pulmonary hypertension (PH) due to left heart disease (LHD) is most common and primarily affects PVs. Next, it is unknown whether activation of PDGFR alters the pulmonary venous tone. Due to the reported adverse effects of systemic imatinib, we evaluated the effects of nebulized imatinib on the postcapillary resistance.

Methods

Precision-cut lung slices (PCLS) were prepared from guinea pigs. PVs were pre-constricted with Endothelin-1 (ET-1) and the imatinib-induced relaxation was studied by videomicroscopy; PDGF-BB-related vascular properties were evaluated as well. The effects of perfused/nebulized imatinib on the postcapillary resistance were studied in cavine isolated perfused lungs (IPL). Intracellular cAMP/cGMP was measured by ELISA in PVs.

Results

In PCLS, imatinib (100 μM) relaxed pre-constricted PVs (126%). In PVs, imatinib increased cAMP, but not cGMP and inhibition of adenyl cyclase or protein kinase A reduced the imatinib-induced relaxation. Further, inhibition of K_ATP-channels, \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ {\mathrm{BK}}_{\mathrm{Ca}}^{2+} $$\end{document}BKCa2+-channels or K_v-channels diminished the imatinib-induced relaxation, whereas inhibition of NO-signaling was without effect. In the IPL, perfusion or nebulization of imatinib reduced the ET-1-induced increase of the postcapillary resistance. In PCLS, PDGF-BB contracted PVs, which was blocked by imatinib and by the PDGFR-β kinase inhibitor SU6668, whereas inhibition of PDGFR-α (ponatinib) had no significant effect. Conversely, PDGFR-β kinase inhibitors (SU6668/DMPQ) relaxed PVs pre-constricted with ET-1 comparable to imatinib, whereas the PDGFR-α kinase inhibitor ponatinib did not.

Conclusions

Imatinib-induced relaxation depends on cAMP and on the activation of K⁺-channels. Perfused or nebulized imatinib significantly reduces the postcapillary resistance in the pre-constricted (ET-1) pulmonary venous bed. Hence, nebulization of imatinib is feasible and might reduce systemic side effects. Conversely, PDGF-BB contracts PVs by activation of PDGFR-β suggesting that imatinib-induced relaxation depends on PDGFR-β-antagonism. Imatinib combines short-term relaxant and long-term antiproliferative effects. Thus, imatinib might be a promising therapy for PH due to LHD.

Inotropes and inodilators for acute heart failure: sarcomere active drugs in focus

Acute heart failure (AHF) emerges as a major and growing epidemiological concern with high morbidity and mortality rates. Current therapies in patients with acute heart failure rely on different strategies. Patients with hypotension, hypoperfusion, or shock require inotropic support, whereas diuretics and vasodilators are recommended in patients with systemic or pulmonary congestion. Traditionally inotropic agents, referred to as Ca²⁺ mobilizers load the cardiomyocyte with Ca²⁺ and thereby increase oxygen consumption and risk for arrhythmias. These limitations of traditional inotropes may be avoided by sarcomere targeted agents. Direct activation of the cardiac sarcomere may be achieved by either sensitizing the cardiac myofilaments to Ca²⁺ or activating directly the cardiac myosin. In this review, we focus on sarcomere targeted inotropic agents, emphasizing their mechanisms of action and overview the most relevant clinical considerations.

Levosimendan: The current situation and new prospects

Levosimendan is a pyridazinone-dinitrile derivative with positive inotropic and vasodilatory effects that has beneficial effects on myocardial performance. In previous randomized studies levosimendan improved hemodynamics and clinical course, but its effect on prognosis is still unclear. This important issue has limited its use. Although primarily used in the management of acute heart failure syndromes, this new inotropic agent may play a role in other clinical conditions. This review aims to summarize current knowledge on levosimendan and to present future prospects for the use of this drug.

Levosimendan exerts anti-inflammatory effects on cardiac myocytes and endothelial cells in vitro

Levosimendan is a positive inotropic drug for the treatment of acute decompensated heart failure (HF). Clinical trials showed that levosimendan was particularly effective in HF due to myocardial infarction. Myocardial necrosis induces a strong inflammatory response, involving chemoattractants guiding polymorphonuclear neutrophils (PMN) into the infarcted myocardial tissue. Our aim was to examine whether levosimendan exhibits anti-inflammatory effects on human adult cardiac myocytes (HACM) and human heart microvascular endothelial cells (HHMEC). Cardiac myocytes and endothelial cells were stimulated with interleukin-1β (IL)-1β (200 U/ml) and treated with levosimendan (0.1-10 µM) for 2-48 hours. IL-1β strongly induced expression of IL-6 and IL-8 in HACM and E-selectin and intercellular adhesion molecule-1 (ICAM-1) in HHMEC and human umbilical vein endothelial cells (HUVEC). Treatment with levosimendan strongly attenuated IL-1β-induced expression of IL-6 and IL-8 in HACM as well as E-selectin and ICAM-1 in ECs. Levosimendan treatment further reduced adhesion of PMN to activated endothelial cells under both static and flow conditions by approximately 50 %. Incubation with 5-hydroxydecanoic acid, a selective blocker of mitochondrial ATP-dependent potassium channels, partly abolished the above seen anti-inflammatory effects. Additionally, levosimendan strongly diminished IL-1β-induced reactive oxygen species and nuclear factor-κB (NF-κB) activity through inhibition of S536 phosphorylation. In conclusion, levosimendan exhibits anti-inflammatory effects on cardiac myocytes and endothelial cells in vitro. These findings could explain, at least in part, the beneficial effects of levosimendan after myocardial infarction.

Levosimendan Relaxes Pulmonary Arteries and Veins in Precision-Cut Lung Slices - The Role of KATP-Channels, cAMP and cGMP

INTRODUCTION

Levosimendan is approved for left heart failure and is also used in right heart failure to reduce right ventricular afterload. Despite the fact that pulmonary arteries (PAs) and pulmonary veins (PVs) contribute to cardiac load, their responses to levosimendan are largely unknown.

MATERIALS AND METHODS

Levosimendan-induced vasorelaxation of PAs and PVs was studied in precision-cut lung slices from guinea pigs by videomicroscopy; baseline luminal area was defined as 100%. Intracellular cAMP- and cGMP-levels were measured by ELISA and NO end products were determined by the Griess reaction.

RESULTS

Levosimendan relaxed control PVs (116%) and those pre-constricted with an endothelinA-receptor agonist (119%). PAs were only relaxed if pre-constricted (115%). Inhibition of KATP-channels (glibenclamide), adenyl cyclase (SQ 22536) and protein kinase G (KT 5823) largely attenuated the levosimendan-induced relaxation in control PVs, as well as in pre-constricted PAs and PVs. Inhibition of BKCa (2+)-channels (iberiotoxin) and Kv-channels (4-aminopyridine) only contributed to the relaxant effect of levosimendan in pre-constricted PAs. In both PAs and PVs, levosimendan increased intracellular cAMP- and cGMP-levels, whereas NO end products remained unchanged. Notably, basal NO-levels were higher in PVs. The KATP-channel activator levcromakalim relaxed PAs dependent on cAMP/PKA/PKG and increased cAMP-levels in PAs.

DISCUSSION

Levosimendan initiates complex and divergent signaling pathways in PAs and PVs. Levosimendan relaxes PAs and PVs primarily via KATP-channels and cAMP/cGMP; in PAs, BKCa (2+)- and Kv-channels are also involved. Our findings with levcromakalim do further suggest that in PAs the activation of KATP-channels leads to the production of cAMP/PKA/PKG. In conclusion, these results suggest that levosimendan might reduce right ventricular afterload by relaxation of PAs as well as pulmonary hydrostatic pressure and pulmonary edema by relaxation of PVs.

Nicorandil inhibits hypoxia-induced apoptosis in human pulmonary artery endothelial cells through activation of mitoKATP and regulation of eNOS and the NF-κB pathway

Apoptosis of human pulmonary artery endothelial cells (HPAECs) is the initial step and triggering event for pulmonary hypertension (PH). However, little is known about the actions of nicorandil on HPAECs in vitro. In the present study, we investigated the anti-apoptotic effect of nicorandil on HPAECs exposed to hypoxia, and explored the underlying mechanism(s) of action. Cell viability was assessed using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT). Annexin V and propidium iodide staining, and Hoechst 33342 staining assay were employed to detect apoptosis. In addition, the protein expression of Bax, Bcl-2, caspase-9 and -3, endothelial nitric oxide synthase (eNOS), nuclear factor-κB (NF-κB) and IκBα were determined by western blotting to investigate the possible mechanisms. We found that exposure to hypoxia for 24 h significantly decreased cell viability and increased cell apoptosis. Pretreatment with nicorandil (100 µM) effectively abolished the influence of hypoxia on HPAECs. However, these protective effects of nicorandil were significantly inhibited by an antagonist of mitochondrial adenosine triphosphate-sensitive potassium (mitoKATP) channels, 5-hydroxydecanoate (5-HD, 500 µM), and by an eNOS inhibitor, NG-nitro-L-arginine methyl ester (L-NAME, 300 µM). We further observed that nicorandil could upregulate the decreased protein expression of eNOS and IκBα, and downregulate the increased protein expression of NF-κB, induced by hypoxia. In addition, nicorandil inhibited the enhancement of caspase-3 and -9 expression, and the increase in the Bax/Bcl-2 expression ratio, induced by hypoxia. However, these effects were also abolished by 5-HD and L-NAME. Collectively, these findings suggest that nicorandil inhibits hypoxia-induced apoptosis of HPAECs through activation of mitoKATP channels and increased eNOS expression, which in turn inhibits the NF-κB pathway and the mitochondrial apoptotic pathway.

Pharmacology of levosimendan: inotropic, vasodilatory and cardioprotective effects

WHAT IS KNOWN AND OBJECTIVE

Positive inotropic agents are frequently used in acute decompensated heart failure (ADHF) due to left ventricular systolic dysfunction. These agents are known to improve cardiac performance and peripheral perfusion in the short-term treatment. However, several preclinical and clinical studies emphasized detrimental effects of these drugs on myocardial oxygen demand and on sympathetic tone entailing arrhythmogenesis. Levosimendan is an inotropic agent with an original mechanism of action. This review focuses on major data available for levosimendan.

METHODS

A literature search was conducted in the PubMed database by including studies published in English using combinations of the following key words, levosimendan, inotropic drugs and acute heart failure. Furthermore, bibliographies of selected references were also evaluated for relevant articles. The collection for this review was limited to the most recently available human and animal data.

RESULTS AND DISCUSSION

Levosimendan's vasodilatory and cardioprotective effects are mediated by calcium sensitization of contractile proteins and opening of adenosine triphosphate (ATP)-dependent K+ channels in vascular smooth muscle cells and on mitochondrial ATP-sensitive potassium [mito.K(ATP)] channels. This inotropic agent has mild PDE inhibitory action. Unlike other inotropic agents, levosimendan improves cardiac performance without activating the sympathetic nervous system. Moreover, there are evidences that levosimendan has additional anti-inflammatory and anti-apoptotic properties that prevent cardiac toxicity and contributes to positive hemodynamic response of the drug. Four randomized trials evaluated the effects of levosimendan on mortality in patients with acute decompensated chronic heart failure; nevertheless, a clear benefit has not been demonstrated so far. Although levosimendan is indicated for the treatment of ADHF (class of recommendation IIa, level of evidence B), it is has not been approved in all countries.

WHAT IS NEW AND CONCLUSION

This review summarizes the characteristics and the current knowledge of the literature on levosimendan and its active metabolite OR-1896.

Pulmonary hypertension in canine degenerative mitral valve disease

Pulmonary hypertension secondary to degenerative mitral valve disease has been recognized clinically for many years in veterinary medicine, and clinical diagnosis of this syndrome in dogs has been enhanced greatly by widespread use of echocardiography and Doppler echocardiography. Medical therapy is now available to treat this clinical complication of mitral valve disease, making timely diagnosis even more important to patient longevity and quality of life.

The antiangiogenic effects of levosimendan in a CAM assay

BACKGROUND

There is a physiological balance between the stimulatory and inhibitory signals for blood vessel growth. In many symptomatic patients with peripheral artery disease, coronary artery disease, and ischemic chronic wounds, there is a pathological insufficiency of angiogenesis. Therefore, determining the angiogenic or antiangiogenic effects of molecules currently used in cardiovascular treatment is crucial. Although levosimendan is the most well studied calcium sensitizer in preclinical and clinical practice, to the best of our knowledge, there are no previous studies investigating its angiogenic or antiangiogenic effects. In the present study, we aimed to investigate the effects of levosimendan on angiogenesis.

METHODS

The antiangiogenic efficacy of levosimendan was examined in vivo in the chick chorioallantoic membrane (CAM) model by using 20 fertilized eggs and drug solutions of 1 and 10 μmol/L concentrations. Decreases in the density of the capillaries were assessed and scored.

RESULTS

Significant antiangiogenic effects were observed at 1 and 10 μmol/L concentrations of levosimendan. The antiangiogenic scores of levosimendan at 1 and 10 μmol/L concentrations were 0.6 and 1.10, respectively. The antiangiogenic score of bevacizumab, used as a positive control, was 0.95 at 1.0 μmol/L concentration. No significant difference was found between the antiangiogenic scores of levosimendan and bevacizumab (p=0.54).

CONCLUSIONS

Our results indicate that levosimendan has antiangiogenic effects on the chorioallantoic membrane. However, these findings must be confirmed in future studies on humans.