The transient vanilloid receptor potential type 1 (TRPV1) regulates neuronal and vascular functions mediated by nitric oxide (NO) and by the calcitonin gene-related peptide (CGRP). Here we study the participation of TRPV1 in the regulation of myocardial injury caused by ischemia-reperfusion and in the regulation of NO, tetrahydrobiopterin (BH4), the cGMP pathway, CGRP, total antioxidant capacity (TAC), malondialdehyde (MDA) and phosphodiesterase-3 (PDE-3). Isolated hearts of Wistar rats were used (according to Langendorff) to study the effects of capsaicin (CS), capsazepine (CZ) and CZ+CS treatments. The hearts were divided into three subgroups; 1) perfusion, 2) ischemia and 3) ischemia-reperfusion. In all groups we studied cardiac work and levels of NO, cGMP, BH4, CGRP, TAC, MDA and PDE-3 in ventricular tissue. Western blots were used to determine the expressions of eNOS, iNOS and phosphorylated NOS (pNOS). Structural changes were determined by histological evaluation. CS prevented damage caused by ischemia-reperfusion by improving cardiac work and the levels of NO, cGMP, BH4, TAC and CGRP. TRPV1 and iNOS expression were increased under ischemic conditions, while eNOS and pNOS were not modified. We conclude that the activation of TRPV1 constitutes a therapeutic possibility to counteract the damage caused by ischemia and reperfusion by regulating the NO pathway through CGRP.

Bile acids (BA) are classically known as an agent important in lipid absorption and cholesterol metabolism. Nowadays, BAs have been found to be involved in various cellular signaling pathways such as protein kinase cascades, cyclic AMP (cAMP) synthesis and calcium mobilization. In addition, they have also been shown to regulate glucose and energy homeostasis. Bile acids are ligands for several nuclear hormone receptors, including FXR. Recently, muscarinic receptor and TGR5, G-protein-coupled receptor (GPCR), have been suggested to play a role in bile acid activity which is independent of nuclear hormone receptors. Moreover, BAs have also been studied in other GPCR associated pathways, namely sphingosine-1-posphate and glucagon receptor. Hydrophobic bile acids have been proven to affect heart rate and its contraction. Elevated bile acids are associated with arrhythmias in adults and fetal heart. Altered ratios of primary and secondary bile acid are reported in chronic heart failure patients. Meanwhile in patients with liver cirrhosis, cardiac dysfunction has been strongly linked to the increase of serum bile acid concentrations. In contrast, the most hydrophilic BA known as ursodeoxycholic acid has been found beneficial in improving peripheral blood flow in chronic heart failure patients and protecting heart against reperfusion injury.

Abstract: (1) Background and Objective: MicroRNAs (miR) are biomarkers for assessing the extent of cardiac remodeling after myocardial infarction (MI) and important predictors of clinical outcome in heart failure. Overexpression of miR-30d appears to have a cardioprotective effect. The aim of the present study was to demonstrate whether miR-30d could be used as a potential therapeutic target to improve post-MI adverse remodeling. (2) Methods and Results: MiR profiling was performed by next generation sequencing to assess different expression patterns in ischemic vs. healthy myocardium in a rat model of MI. MiR-30d was significantly downregulated (p<0.001) in ischemic myocardium and was selected as promising target. A mimic of miR-30d was administered in the respective treatment group, whereas control group received non-functional, scrambled siRNA. To measure the effect of miR-30d on infarct area size of left ventricle, rats were randomized and treated with miR-30d or scrambled siRNA. Histological planimetry was performed 72 hours and 6 weeks after induction of MI. Infarct area was significantly reduced at 72 hours and at 6 weeks by using the miR-30d (72 hours: 22.89±7.66% vs. 35.96±9.27%, p=0.0136; 6 weeks: 6.93±4.58% vs. 12.48±7.09%; p=0.0172). To gain insight into infarct healing, scratch assays were used to obtain information on cell migration in human umbilical vein endothelial cells (HUVEC). Gap closure was significantly faster in the mimic-treated cells 20h post-scratching (12.4% more than scrambled control after 20h; p=0.013). To analyze anti-apoptotic quality of miR-30d, the ratio between phosphorylated p53 and total p53 was evaluated in human cardiomyocytes using ELISA. Under the influence of miR-30d mimic, cardiomyocytes demonstrated a decreased pp53/total p53 ratio (0.66±0.08 vs. 0.81±0.17), showing a distinct tendency (p=0.055) to decrease apoptosis rate compared to the control group. (3) Conclusion: Using a mimic of miR-30d underlines the cardioprotective effect of miR-30d in MI and could reduce the risk for development of ischemic cardiomyopathy.

Acute myocardial infarction (AMI), which is characterized by severe and fatal arrhythmias resultant from cardiac ischemia/reperfusion (CIR), is the leading cause of morbidity and mortality in the world. Considering that epiisopiloturin (EPI), an imidazole alkaloid found in the leaves of Pilocarpus microphyllus produded anti-inflammatory and antioxidant effects in an animal model of peritonitis, paw edema and peritonitis in mice, we decided to investigate the potential cardioprotective activity of EPI in animal model of CIR. Then, adult rats submitted to CIR pretreated with EPI 10 mg/kg (EPI10+CIR group) or 15 mg/kg (EPI15+CIR group) were compared to control animals submitted to CIR treated with saline solution 0.9% (CIR group). To evaluate the incidence of ventricular arrhythmias (VA), atrioventricular block (AVB) and lethality (LET) induced by CIR in these rats, the ECG analysis was performed. Serum levels of cardiac damage markers, total creatine kinase (CK) and CK-MB, were measured. The results showed that the AVB incidence was reduced from 80% to 30%, and LET incidence was reduced from 70% to 20%, compared to CIR group. Serum levels of LDH, total CK and, CK-MB was similar in all groups studied. These results indicate that the treatment with EPI (15 mg/kg, IV) before CIR was effective to produce cardioprotective effects. Thus, the use of EPI could be a promisse strategy to reduce the incidence of severe and fatal arrhythmias associated with AMI.

The thyroid-heart relationship has a long and articulated history of its own, a history that en-compasses physiological and pathophysiological knowledge, the latter particularly in the context of cardiac diseases such as heart failure, arrhythmias and ischaemic heart disease. In recent years, molecular biology studies, in an experimental context, have highlighted the extraordinary dialogue that exists among the two systems in the field of cardioprotection, being an extremely important area for the treatment of cardiac diseases in both acute and chronic phases. In addi-tion, in the last few years, several studies have been carried out on the prognostic impact of al-terations in thyroid function, including subclinical ones, in heart disease, in particular in heart failure and acute myocardial infarction, with evidence of a negative prognostic impact of these and therefore with the suggestion to treat these alterations in order to prevent cardiac events, such as death. This review provides a comprehensive summary of the heart-thyroid relation-ship.

Characterized by severe and fatal arrhythmias induced by cardiac ischemia/reperfusion (CIR), acute myocardial infarction (AMI) is the main cause of morbidity and mortality worldwide. To investigate the cardioprotective role of cardiac Ca2+/cAMP/adenosine signaling in AMI, the effects of L-type Ca2+ channels (LTCC) blocker Nifedipine (NIF) and Verapamil (VER), in the absence and presence of A1-adenosine receptors (A1R) blocker (DPCPX), on the incidence of ventricular arrhythmias (VA), atrioventricular block (AVB) and lethality (LET) induced by CIR in rats were evaluated. CIR was induced in adult male Wistar rats (290-320 g) by occlusion of the left anterior descendent coronary artery (10 min) followed by reperfusion (75 min). VA, AVB and LET incidences were evaluated by ECG analysis and compared between control (CIR group) and intravenously treated 5 min before CIR with NIF 1, 10, and 30 mg/kg (NIF+CIR groups) or DPCPX 100 µg/kg plus NIF 10 mg/kg (DPCPX+NIF+CIR group) and VER 1 mg/kg (VER+CIR group) or DPCPX 100 µg/kg plus VER 1 mg/kg (DPCPX+VER+CIR group). Serum levels of cardiac injury biomarkers (TCK and CK-MB) were quantified. In CIR group, VA, AVB and LET incidences were 90, 80 and 70%, respectively. In NIF+CIR group, incidence of VA was reduced to 50, 30 and 30%, AVB to 25, 10 and 20%, and LET to 25, 20 and 20%, and respectively. In DPCPX+NIF+CIR group, these incidences were not different from CIR group. TCK and CK-MB levels were similar in all groups. These results indicate that pharmacological modulation of the Ca2+/cAMP/adenosine signaling in cardiac cells by LTCC blockade and A1R stimulation could be a new strategy cardioprotective for human AMI therapy.

Background: The hypothesis is that a hypoxic-hyperoxic preconditioning (HHP) is associated with a protective effect on myocardial function by reducing endothelial damage and a beneficial effect on postoperative outcome in patients undergoing cardiac surgery with cardiopulmonary bypass (CPB). Methods: Patients (n=120) were randomly assigned to an HHP and a control group. A safe inhaled oxygen fraction for the hypoxic preconditioning phase (10-14% oxygen for 10 minutes) was determined by measuring the anaerobic threshold. At hyperoxic phase, 75-80% oxygen fraction was used during 30 minutes. Results: The cumulative frequency of postoperative complications was 14 (23.3%) in the HHP vs 23 (41.1%), p=0.041. The nitrate decreased after surgery by up to 20% in the HHP group and up to 38% in the control group. Endothelin-1 and nitric oxide metabolites were stable in HHP but remained low more than 24 h in control group. The endothelial damage markers appeared to be predictors of postoperative complications. Conclusion: The HHP with individual parameters based on the anaerobic threshold is a safe procedure, it can reduce the frequency of postoperative complications. The endothelial damage markers appeared to be predictors of postoperative complications.

Heat shock proteins (HSPs) are a family of molecular chaperones that regulate essential protein refolding and triage decisions to maintaining protein homeostasis. Numerous co-chaperone proteins directly interact and modify the function of HSPs, and these interactions impact the outcome of protein triage, impacting everything from structural proteins to cell signaling mediators. The chaperone/co-chaperone machinery protects against various stressors to ensuring cellular function in the face of stress. However, coding mutations, expression changes, and post-translational modifications of the chaperone/co-chaperone machinery can alter the cellular stress response. Importantly, these dysfunctions appear to contribute to numerous human diseases. Therapeutic targeting of chaperones is an attractive but challenging approach due to the vast functions of HSPs, likely contributing to the off-target effects of these therapies. Current efforts focus on targeting co-chaperones to develop precise treatments for numerous diseases caused by defects in protein quality control. This review focuses on the recent developments regarding selected HSP70/HSP90 co-chaperones, focusing on cardioprotection, neuroprotection, and cancer. We also discuss therapeutic approaches that highlight both the utility and challenges of targeting co-chaperones.

Mitochondrial dysfunction is relevant mechanism in cardiac aging. Here, we investigated the effects of late-life enalapril administration at non-antihypertensive dose on mitochondrial genomic stability, oxidative damage, and mitochondrial quality control (MQC) signaling in the heart of aged rats. The protein expression of selected mediators (i.e., mitochondrial antioxidant enzymes, energy metabolism, mitochondrial biogenesis, dynamics, and autophagy) was measured in old rats randomly assigned to receive enalapril (n=8) or placebo (n=8) from 24 to 27 months of age. We also assessed mitochondrial DNA (mtDNA) content, citrate synthase activity, oxidative lesions to protein and mtDNA (i.e., carbonyls and abundance of mtDNA4834 deletion), and mitochondrial transcription factor A (TFAM) binding to specific mtDNA regions. Enalapril attenuated cardiac hypertrophy and oxidative stress-derived damage (mtDNA oxidation, mtDNA4834 deletion, and protein carbonylation), while increasing mitochondrial antioxidant defenses. TFAM binding to mtDNA regions involved in replication and deletion generation was increased following enalapril administration. Increased mitochondrial mass as well as mitochondriogenesis and autophagy signaling was found in enalapril-treated rats. Late-life enalapril administration mitigates age-dependent cardiac hypertrophy and oxidative damage, while increasing mitochondrial mass and modulating MQC signaling. Further analyses are needed to conclusively establish whether enalapril may offer cardioprotection during aging.