Dopamine induces postischemic cardiomyocyte apoptosis in vivo: an effect ameliorated by propofol

Apoptosis and long non-coding RNAs: Focus on their roles in Heart diseases

Heart disease is one of the principal death reasons around the world and there is a growing requirement to discover novel healing targets that have the potential to avert or manage these illnesses. On the other hand, apoptosis is a strongly controlled, cell removal procedure that has a crucial part in numerous cardiac problems, such as reperfusion injury, MI (myocardial infarction), consecutive heart failure, and inflammation of myocardium. Completely comprehending the managing procedures of cell death signaling is critical as it is the primary factor that influences patient mortality and morbidity, owing to cardiomyocyte damage. Indeed, the prevention of heart cell death appears to be a viable treatment approach for heart illnesses. According to current researches, a number of long non-coding RNAs cause the heart cells death via different methods that are embroiled in controlling the activity of transcription elements, the pathways that signals transmission within cells, small miRNAs, and the constancy of proteins. When there is too much cell death in the heart, it can cause problems like reduced blood flow, heart damage after restoring blood flow, heart disease in diabetics, and changes in the heart after reduced blood flow. Therefore, studying how lncRNAs control apoptosis could help us find new treatments for heart diseases. In this review, we present recent discoveries about how lncRNAs are involved in causing cell death in different cardiovascular diseases.

Ivabradine prevents deleterious effects of dopamine therapy in heart failure: No role for HCN4 overexpression

BACKGROUND

Exacerbations of chronic heart failure (CHF) are often treated with catecholamines to provide short term inotropic support, but this strategy is associated with long-term detrimental hemodynamic effects and increased ventricular arrhythmias (VA), possibly related to increased heart rate (HR). We hypothesized that ivabradine may prevent adverse effects of short-term dopamine treatment in CHF.

METHODS

Rats with post-myocardial infarction CHF received 2-week infusion of saline, dopamine(D), ivabradine(I) or D&I; cardiac function was assessed using echocardiography and pressure-volume loops while VA were assessed using telemetric ECG recording. Expression of HCN4, a potentially proarrhythmic channel blocked by ivabradine, was assessed in left ventricular (LV) myocardium. HCN4 expression was also assessed in human explanted normal and failing hearts and correlated with VA.

FINDINGS

Dopamine infusion had detrimental effects on hemodynamic parameters and LV remodeling and induced VA in CHF rats, while ivabradine completely prevented these effects. CHF rats demonstrated HCN4 overexpression in LV myocardium, and ivabradine and, unexpectedly, dopamine prevented this. Failing human hearts also exhibited HCN4 overexpression in LV myocardium that was unrelated to patient's sex, CHF etiology, VA severity or plasma NT-proBNP.

INTERPRETATION

HR reduction offered by ivabradine may be a feasible strategy to extract benefits of inotropic support in CHF exacerbations, avoiding detrimental effects on CHF biology or VA. Ivabradine may offer additional beneficial effects in this setting, going beyond pure HR reduction, however prevention of ventricular HCN4 overexpression is unlikely to play a major role.

miR-30e-3p Promotes Cardiomyocyte Autophagy and Inhibits Apoptosis via Regulating Egr-1 during Ischemia/Hypoxia

Background

Microvascular obstruction (MVO) can result in coronary microcirculation embolism and myocardial microinfarction. Myocardial injury induced by MVO is characterized by continuous ischemia and hypoxia of cardiomyocytes. Autophagy and apoptosis are closely associated with various cardiovascular diseases. Based on our previous study, we observed a decrease in miR-30e-3p expression and an increase in Egr-1 expression in a rat coronary microembolization model. However, the specific function of miR-30e-3p in regulating autophagy and apoptosis in an ischemia/hypoxia (IH) environment remains to be deciphered. We exposed cardiomyocytes to an IH environment and then determined whether miR-30e-3p was involved in promoting cardiomyocyte autophagy and inhibiting apoptosis by regulating Egr-1.

Methods

Cardiomyocytes were isolated from rats for our in vitro study. miR-30e-3p was either overexpressed or inhibited by transfection with lentiviral vectors into cardiomyocytes. 3-Methyladenine (3-MA) was used to inhibit autophagy. RT-qPCR and western blotting were used to determine the expression levels of miR-30e-3p, Egr-1, and proteins related to the autophagy and apoptosis process. Autophagic vacuoles and autophagic flux were evaluated using transmission electron microscopy (TEM) and confocal microscopy, respectively. Cardiomyocyte viability was evaluated using the MTS assay. Cell injury was assessed by lactate dehydrogenase (LDH) leakage, and apoptosis was determined by flow cytometry.

Results

Both miR-30e-3p expression and autophagy were significantly inhibited, and apoptosis was increased in cardiomyocytes after 9 hours of IH exposure. Overexpression of miR-30e-3p increased autophagy and inhibited apoptosis, as well as suppressed Egr-1 expression and decreased cell injury. In addition, inhibition of miR-30e-3p reduced autophagy and increased apoptosis and cell injury.

Conclusions

miR-30e-3p may be involved in promoting cardiomyocyte autophagy and inhibiting apoptosis by indirectly regulating Egr-1 expression in an IH environment.

Hurdles to Cardioprotection in the Critically Ill

Cardiovascular disease is the largest contributor to worldwide mortality, and the deleterious impact of heart failure (HF) is projected to grow exponentially in the future. As heart transplantation (HTx) is the only effective treatment for end-stage HF, development of mechanical circulatory support (MCS) technology has unveiled additional therapeutic options for refractory cardiac disease. Unfortunately, despite both MCS and HTx being quintessential treatments for significant cardiac impairment, associated morbidity and mortality remain high. MCS technology continues to evolve, but is associated with numerous disturbances to cardiac function (e.g., oxidative damage, arrhythmias). Following MCS intervention, HTx is frequently the destination option for survival of critically ill cardiac patients. While effective, donor hearts are scarce, thus limiting HTx to few qualifying patients, and HTx remains correlated with substantial post-HTx complications. While MCS and HTx are vital to survival of critically ill cardiac patients, cardioprotective strategies to improve outcomes from these treatments are highly desirable. Accordingly, this review summarizes the current status of MCS and HTx in the clinic, and the associated cardiac complications inherent to these treatments. Furthermore, we detail current research being undertaken to improve cardiac outcomes following MCS/HTx, and important considerations for reducing the significant morbidity and mortality associated with these necessary treatment strategies.

Sedation After Cardiac Surgery: Is One Drug Better Than Another?

The classic high-dose narcotic-based cardiac anesthetic has been modified to facilitate a fast-track, rapid recovery in the intensive care unit (ICU). Postoperative sedation is consequently now an essential component in recovery of the patient undergoing cardiac surgery. It must facilitate the patient's unawareness of the environment as well as reduce the discomfort and anxiety caused by surgery, intubation, mechanical ventilation, suction, and physiotherapy. Benzodiazepines seem well suited for this role, but propofol, opioids, and dexmedetomidine are among other agents commonly used for sedation in the ICU. However, what is an ideal sedative for this application? When compared with benzodiazepine-based sedation regimens, nonbenzodiazepines have been associated with shorter duration of mechanical ventilation and ICU length of stay. Current sedation guidelines recommend avoiding benzodiazepine use in the ICU. However, there are no recommendations on which alternatives should be used. In postcardiac surgery patients, inotropes and vasoactive medications are often required because of the poor cardiac function. This makes sedation after cardiac surgery unique in comparison with the requirements for most other ICU patient populations. We reviewed the current literature to try to determine if 1 sedative regimen might be better than others; in particular, we compare outcomes of propofol and dexmedetomidine in postoperative sedation in the cardiac surgical ICU.

Radiofluorinated N-Octanoyl Dopamine ([18F]F-NOD) as a Tool To Study Tissue Distribution and Elimination of NOD in Vitro and in Vivo

To mitigate pretransplantation injury in organs of potential donors, N-octanoyl dopamine (NOD) treatment might be considered as it does not affect hemodynamic parameters in braindead (BD) donors. To better assess optimal NOD concentrations for donor treatment, we report on the fast and facile radiofluorination of the NOD-derivative [¹⁸F]F-NOD [¹⁸F]5 for in vivo assessment of NOD's elimination kinetics by means of PET imaging. [¹⁸F]5 was synthesized in reproducibly high radiochemical yields and purity (>98%) as well as high specific activities (>20 GBq/μmol). Stability tests showed no decomposition of [¹⁸F]5 over a period of 120 min in rat plasma. In vitro, low cell association was found for [¹⁸F]5, indicating no active transport mechanism into cells. In vivo, [¹⁸F]5 exhibited a fast blood clearance and a predominant hepatobiliary elimination. As these data suggest that also NOD might be cleared fast, further pharmacokinetic evaluation is warranted.

Propofol protects the immature rabbit heart against ischemia and reperfusion injury: impact on functional recovery and histopathological changes

The general anesthetic propofol protects the adult heart against ischemia and reperfusion injury; however, its efficacy has not been investigated in the immature heart. This work, for the first time, investigates the cardioprotective efficacy of propofol at clinically relevant concentrations in the immature heart. Langendorff perfused rabbit hearts (7–12 days old) were exposed to 30 minutes' global normothermic ischemia followed by 40 minutes' reperfusion. Left ventricular developed pressure (LVDP) and coronary flow were monitored throughout. Lactate release into coronary effluent was measured during reperfusion. Microscopic examinations of the myocardium were monitored at the end of reperfusion. Hearts were perfused with different propofol concentrations (1, 2, 4, and 10 μg/mL) or with cyclosporine A, prior to ischemic arrest and for 20 minutes during reperfusion. Propofol at 4 and 10 μg/mL caused a significant depression in LVDP prior to ischemia. Propofol at 2 μg/mL conferred significant and maximal protection with no protection at 10 μg/mL. This protection was associated with improved recovery in coronary flow, reduced lactate release, and preservation of cardiomyocyte ultrastructure. The efficacy of propofol at 2 μg/mL was similar to the effect of cyclosporine A. In conclusion, propofol at a clinically relevant concentration is cardioprotective in the immature heart.

Small molecules, big effects: the role of microRNAs in regulation of cardiomyocyte death

MicroRNAs (miRNAs) are a class of small non-coding RNAs involved in posttranscriptional regulation of gene expression, and exerting regulatory roles in plethora of biological processes. In recent years, miRNAs have received increased attention for their crucial role in health and disease, including in cardiovascular disease. This review summarizes the role of miRNAs in regulation of cardiac cell death/cell survival pathways, including apoptosis, autophagy and necrosis. It is envisaged that these miRNAs may explain the mechanisms behind the pathogenesis of many cardiac diseases, and, most importantly, may provide new avenues for therapeutic intervention that will limit cardiomyocyte cell death before it irreversibly affects cardiac function. Through an in-depth literature analysis coupled with integrative bioinformatics (pathway and synergy analysis), we dissect here the landscape of complex relationships between the apoptosis-regulating miRNAs in the context of cardiomyocyte cell death (including regulation of autophagy–apoptosis cross talk), and examine the gaps in our current understanding that will guide future investigations.

In vivo effects of different anesthetic agents on apoptosis

Background

This study was designed to measure in vivo effects of propofol, isoflurane and sevoflurane on apoptosis by measuring caspase-3 and tumor necrosis factor (TNF)-related apoptosis inducing ligand (TRAIL) blood level as apoptotic markers.

Methods

After obtaining ethical committee approval and informed written consents, sixty adult patients ASA I scheduled for open cholecystectomy participated in this study. They were randomally allocated into one of three equal groups to receive propofol infusion, low-flow isoflurane or sevoflurane for maintenance of anesthesia. Venous blood samples were collected preoperatively, immediately postoperative and after 24 hours to measure hemoglobin, hematocrit, creatinine, liver enzymes, serum TRAIL and caspase-3 levels.

Results

There was no significant difference in hematological markers and serum creatinine. Liver enzymes showed significant postoperative rise (P < 0.05). In Propofol group, TRAIL and caspase-3 levels were significantly elevated immediately postoperative then decreased significantly after 24-hours (P < 0.05). In Isoflurane group, immediate postoperative level of TRAIL was significantly higher than 24 hours reading and significantly lower than its level in Propofol group at the same timing meanwhile caspase-3 levels were comparable at different timings. In Sevoflurane group, TRAIL and caspase-3 levels increased significantly in both postoperative samples than preoperative level and than those of Isoflurane and Propofol groups after 24 hours concerning TRAIL (P & 0.05).

Conclusions

This study concluded that isoflurane is superior and sevoflurane is the least effective among the three anesthetics in protection against apoptosis. This study neither proved nor excluded propofol-induced apoptosis. Further studies are required during lengthy procedure and in compromised patients.

Total intravenous anesthesia (TIVA) in pediatric cardiac anesthesia

Although inhalational anesthesia with moderate- to high-dose opioid analgesia has been the mainstay of pediatric cardiac anesthesia, the availability of new short-acting drugs, new concepts in pharmacokinetic modeling and computer technology, and advances in surgery and perfusion have made total intravenous anesthesia (TIVA) an attractive option. In this article, we review some of the TIVA techniques used in pediatric cardiac anesthesia.

Dopamine as additive to cold preservation solution improves postischemic integrity of the liver

Dopamine pretreatment has been used to confer protection against cellular injury following hypothermia or anoxia, especially in vascular endothelial cells. Ischemia/reperfusion-associated tissue alterations still represent a major drawback in liver transplantation. The present study was aimed to investigate the effect of dopamine as an ex vivo adjunct, added to the cold storage solution, on cold preservation of the liver. Rat livers were excised 30 min after cardiac arrest, flushed with preservation solution and cold stored for 18 h. Dopamine (10, 50 or 100 microM) was added to the preservation solution in other livers. Organ viability was evaluated by 120 min of warm reperfusion in vitro (n = 6, resp.). Dopamine induced a dose related up to fourfold (at 50 mum) reduction in parenchymal (ALT, LDH) and mitochondrial (GLDH) enzyme release and significantly reduced histologic signs of tissue injury. Bile production and tissue ATP was doubled by dopamine. On the molecular level, dopamine enhanced postischemic phosphorylation of protein kinase A and p42/44 MAP kinase. Inhibition of cAMP-PKA pathway by simultaneous application of RP-cAMPs had no effect on P42/44 phosphorylation, or functional recovery of dopamine-treated grafts. Dopamine supplementation of the flush-out solution appears as a simple way for ex vivo augmentation of liver viability during preservation, not mediated via the catecholamine-cAMP signal cascade.

Development of left ventricular diastolic dysfunction with preservation of ejection fraction during progression of infant right ventricular hypertrophy

BACKGROUND

Progressive left ventricular (LV) dysfunction can be a major late complication in patients with chronic right ventricular pressure overload (eg, tetralogy of Fallot). Therefore, we examined LV function (serial echocardiography and ex vivo Langendorff) and histology in a model of infant pressure-load right ventricular hypertrophy (RVH).

METHODS AND RESULTS

Ten-day-old rabbits (n=6 per time point, total n=48) that underwent pulmonary artery banding were euthanized at 2 to 8 weeks after pulmonary artery banding, and comparisons were made with age-matched sham controls. LV performance (myocardial performance index) decreased during the progression of RVH, although the LV ejection fraction was maintained. In addition, RVH caused significant septal displacement, reduced septal contractility, and decreased LV end-systolic and end-diastolic dimensions, resulting in LV diastolic dysfunction with the appearance of preserved ejection fraction. Significant septal and LV free-wall apoptosis (myocyte-specific TUNEL and activated caspase-3), fibrosis (Masson trichrome stain), and reduced capillary density (CD31 immunostaining) occurred in the pulmonary artery banding group after 6 to 8 weeks (all P<0.05).

CONCLUSIONS

This is the first study showing that pressure overload of the right ventricular resulting in RVH causes LV diastolic dysfunction while preserving ejection fraction through mechanical and molecular effects on the septum and LV myocardium. In particular, the development of RVH is associated with septal and LV apoptosis and reduced LV capillary density.

Inflammatory response and cardioprotection during open-heart surgery: the importance of anaesthetics

Open-heart surgery triggers an inflammatory response that is largely the result of surgical trauma, cardiopulmonary bypass, and organ reperfusion injury (e.g. heart). The heart sustains injury triggered by ischaemia and reperfusion and also as a result of the effects of systemic inflammatory mediators. In addition, the heart itself is a source of inflammatory mediators and reactive oxygen species that are likely to contribute to the impairment of cardiac pump function. Formulating strategies to protect the heart during open heart surgery by attenuating reperfusion injury and systemic inflammatory response is essential to reduce morbidity. Although many anaesthetic drugs have cardioprotective actions, the diversity of the proposed mechanisms for protection (e.g. attenuating Ca(2+) overload, anti-inflammatory and antioxidant effects, pre- and post-conditioning-like protection) may have contributed to the slow adoption of anaesthetics as cardioprotective agents during open heart surgery. Clinical trials have suggested at least some cardioprotective effects of volatile anaesthetics. Whether these benefits are relevant in terms of morbidity and mortality is unclear and needs further investigation. This review describes the main mediators of myocardial injury during open heart surgery, explores available evidence of anaesthetics induced cardioprotection and addresses the efforts made to translate bench work into clinical practice.