Ischaemic preconditioning (IPC) provides myocardial resistance to ischaemia/reperfusion (I/R) injuries. The protection afforded by IPC is not limited to the target tissue but extends to remote tissues, suggesting a mechanism mediated by humoral factors. The aim of the present study was to identify the humoral factors that are responsible for the cardioprotection induced by the coronary effluent transferred from IPC to naïve hearts. Isolated rat hearts were submitted to IPC (three cycles of 5 min I/R) before 30-min global ischaemia and 60-min reperfusion. The coronary effluent (Efl_IPC) collected during IPC was fractionated by ultrafiltration in different molecular weight ranges (<3, 3-5, 5-10, 10-30, 30-50, and >50 kDa) and evaluated for cardioprotective effects by perfusion before I/R in naïve hearts. Only the <3, 5-10 and <10 kDa fractions of hydrophobic eluate reduced I/R injuries. The cardioprotective effect of the 5-10 fraction was blocked by K channel blockers and a PKC inhibitor. An Efl_IPC proteomic analysis revealed 14 cytoprotection-related proteins in 4-12 kDa peptides. HSP10 perfusion protected the heart against I/R injuries. These data provide insights into the mechanisms of cardioprotection in humoral factors released by IPC. Cardioprotection is afforded by hydrophobic peptides in the 4-12 kDa size range, which activate pathways that are dependent on PKC and K. Fourteen 4-12 kDa peptides were identified, suggesting a potential therapeutic role for these molecules in ischaemic diseases. One of these, HSP10, identified by mass spectrometry, reduced I/R injuries and may be a potential candidate as a therapeutic target.

Background CDNF (cerebral dopamine neurotrophic factor) belongs to a new family of neurotrophic factors that exert systemic beneficial effects beyond the brain. Little is known about the role of CDNF in the cardiac context. Herein we investigated the effects of CDNF under endoplasmic reticulum‐stress conditions using cardiomyocytes (humans and mice) and isolated rat hearts, as well as in rats subjected to ischemia/reperfusion (I/R). Methods and Results We showed that CDNF is secreted by cardiomyocytes stressed by thapsigargin and by isolated hearts subjected to I/R. Recombinant CDNF (exoCDNF) protected human and mouse cardiomyocytes against endoplasmic reticulum stress and restored the calcium transient. In isolated hearts subjected to I/R, exoCDNF avoided mitochondrial impairment and reduced the infarct area to 19% when administered before ischemia and to 25% when administered at the beginning of reperfusion, compared with an infarct area of 42% in the untreated I/R group. This protection was completely abrogated by AKT (protein kinase B) inhibitor. Heptapeptides containing the KDEL sequence, which binds to the KDEL‐R (KDEL receptor), abolished exoCDNF beneficial effects, suggesting the participation of KDEL‐R in this cardioprotection. CDNF administered intraperitoneally to rats decreased the infarct area in an in vivo model of I/R (from an infarct area of ≈44% in the I/R group to an infarct area of ≈27%). Moreover, a shorter version of CDNF, which lacks the last 4 residues (CDNF‐ΔKTEL) and thus allows CDNF binding to KDEL‐R, presented no cardioprotective activity in isolated hearts. Conclusions This is the first study to propose CDNF as a new cardiomyokine that induces cardioprotection via KDEL receptor binding and PI3K/AKT activation.

protection is dependent of PKC and mK ATP activation. HSP10 can act directly on mitochondria and protects against hypoxia/reoxygenation injury by mK ATP activation.

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Physical exercise is characterized by an increase in physical and metabolic demand in face of physical stress. It is reported that a single exercise session induces physiological responses through redox signaling to increase cellular function and energy support in diverse organs. However, little is known about the effect of a single bout of exercise on the redox homeostasis and cytoprotective gene expression of white adipose tissue (WAT). Thus, we aimed at evaluating the effects of acute aerobic exercise on WAT redox homeostasis, mitochondrial metabolism, and cytoprotective genic response. Male Wistar rats were submitted to a single moderate-high running session (treadmill) and were divided into five groups: control (CTRL, without exercise), and euthanized immediately (0 h), 30 min, 1 hour, or 2 hours after the end of the exercise session. NADPH oxidase activity was higher in 0 h and 30 min groups when compared to CTRL group. Extramitochondrial ROS production was higher in 0 h group in comparison to CTRL and 2 h groups. Mitochondrial respiration in phosphorylative state increased in 0 h group when compared to CTRL, 30 min, 1, and 2 h groups. On the other hand, mitochondrial ATP production was lower in 0 h in comparison to 30 min group, increasing in 1 and 2 h groups when compared to CTRL and 0 h groups. CAT activity was lower in all exercised groups when compared to CTRL. Regarding oxidative stress biomarkers, we observed a decrease in reduced thiol content in 0 h group compared to CTRL and 2 h groups, and higher levels of protein carbonylation in 0 and 30 min groups in comparison to the other groups. The levels returned to basal condition in 2 h group. Furthermore, aerobic exercise increased NRF2, GPX2, HMOX1, SOD1, and CAT mRNA levels. Taken together, our results suggest that one session of aerobic exercise can induce a transient prooxidative state in WAT, followed by an increase in antioxidant and cytoprotective gene expression.

Background and AimsObesity promotes cardiac and cerebral microcirculatory dysfunction that could be improved by incretin-based therapies. However, the effects of this class of compounds on neuro-cardiovascular system damage induced by high fat diet remain unclear. The aim of this study was to investigate the effects of incretin-based therapies on neuro-cardiovascular dysfunction induced by high fat diet in Wistar rats.Methods and ResultsWe have evaluated fasting glucose levels and insulin resistance, heart rate variability quantified on time and frequency domains, cerebral microcirculation by intravital microscopy, mean arterial blood pressure, ventricular function and mitochondrial swelling. High fat diet worsened biometric and metabolic parameters and promoted deleterious effects on autonomic, myocardial and haemodynamic parameters, decreased capillary diameters and increased functional capillary density in the brain. Biometric and metabolic parameters were better improved by glucagon like peptide-1 (GLP-1) compared with dipeptdyl peptidase-4 (DPP-4) inhibitor. On the other hand, both GLP-1 agonist and DPP-4 inhibitor reversed the deleterious effects of high fat diet on autonomic, myocardial, haemodynamic and cerebral microvascular parameters. GLP-1 agonist and DPP-4 inhibitor therapy also increased mitochondrial permeability transition pore resistance in brain and heart tissues of rats subjected to high fat diet.ConclusionIncretin-based therapies improve deleterious cardiovascular effects induced by high fat diet and may have important contributions on the interplay between neuro-cardiovascular dynamic controls through mitochondrial dysfunction associated to metabolic disorders.

Direct analysis of isolated mitochondria enables a better understanding of lung dysfunction. Despite well-defined mitochondrial isolation protocols applicable to other tissues, such as the brain, kidney, heart, and liver, a robust and reproductive protocol has not yet been advanced for the lung. We describe a protocol for the isolation of mitochondria from lung tissue aiming for functional analyses of mitochondrial O2 consumption, transmembrane potential, reactive oxygen species (ROS) formation, ATP production, and swelling. We compared our protocol to that used for heart mitochondrial function that is well-established in the literature, and achieved similar results.

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