Synergistic impact of endurance training and intermittent hypobaric hypoxia on cardiac function and mitochondrial energetic and signaling

Background Intermittent hypobaric-hypoxia (IHH) and endurance-training (ET) are cardioprotective strategies against stress-stimuli. Mitochondrial modulation appears to be an important step of the process. This study aimed to analyze whether a combination of these approaches provides additive or synergistic effects improving heart-mitochondrial and cardiac-function. Methods Two-sets of rats were divided into normoxic-sedentary (NS), normoxic-exercised (NE, 1 h/day/5 weeks treadmill-running), hypoxic-sedentary (HS, 6000 m, 5 h/day/5 weeks) and hypoxic-exercised (HE) to study overall cardiac and mitochondrial function. In vitro cardiac mitochondrial oxygen consumption and transmembrane potential were evaluated. OXPHOS subunits and ANT protein content were semi-quantified by Western blotting. HIF-1α, VEGF, VEGF-R1 VEGF-R2, BNP, SERCA2a and PLB expressions were measured by qRT-PCR and cardiac function was characterized by echocardiography and hemodynamic parameters. Results Respiratory control ratio (RCR) increased in NE, HS and HE vs. NS. Susceptibility to anoxia/reoxygenation-induced dysfunction decreased in NE, HS and HE vs. NS. HS decreased mitochondrial complex-I and -II subunits; however HE completely reverted the decreased content in complex-II subunits. ANT increased in HE. HE presented normalized ventricular–arterial coupling (Ea) and BNP myocardial levels and significantly improved myocardial performance as evaluated by increased cardiac output and normalization of the Tei index vs. HS. Conclusion Data demonstrates that IHH and ET confer cardiac mitochondria with a more resistant phenotype although without visible addictive effects at least under basal conditions. It is suggested that the combination of both strategies, although not additive, results into improved cardiac function

Early Cardiac Mitochondrial Molecular and Functional Responses to Acute Anthracycline Treatment in Wistar Rats

Doxorubicin (DOX) is an anticancer drug widely used to treat human and nonhuman tumors but the late and persistent cardio-toxicity reduces the therapeutic utility of the drug. The full mechanism(s) of DOX-induced acute, subchronic and delayed toxicity, which has a preponderant mitochondrial component, remains unclear; therefore, it is clinically relevant to identify early markers to identify patients who are predisposed to DOX-related cardiovascular toxicity. To address this, Wistar rats (16 weeks old) were treated with a single DOX dose (20 mg/kg, i.p.); then, mRNA, protein levels and functional analysis of mitochondrial endpoints were assessed 24 h later in the heart, liver, and kidney. Using an exploratory data analysis, we observed cardiac-specific alterations after DOX treatment for mitochondrial complexes III, IV, and preferentially for complex I. Conversely, the same analysis revealed complex II alterations are associated with DOX response in the liver and kidney. Interestingly, H2O2 production by the mitochondrial respiratory chain as well as loss of calcium-loading capacity, markers of subchronic toxicity, were not reliable indicators of acute DOX cardiotoxicity in this animal model. By using sequential principal component analysis and feature correlation analysis, we demonstrated for the first time alterations in sets of transcripts and proteins, but not functional measurements, that might serve as potential early acute markers of cardiac-specific mitochondrial toxicity, contributing to explain the trajectory of DOX cardiac toxicity and to develop novel interventions to minimize DOX cardiac liabilities

Mitochondrionopathy Phenotype in Doxorubicin-Treated Wistar Rats Depends on Treatment Protocol and Is Cardiac-Specific

Although doxorubicin (DOX) is a very effective antineoplastic agent, its clinical use is limited by a dose-dependent, persistent and cumulative cardiotoxicity, whose mechanism remains to be elucidated. Previous works in animal models have failed to use a multi-organ approach to demonstrate that DOX-associated toxicity is selective to the cardiac tissue. In this context, the present work aims to investigate in vivo DOX cardiac, hepatic and renal toxicity in the same animal model, with special relevance on alterations of mitochondrial bioenergetics. To this end, male Wistar rats were sub-chronically (7 wks, 2 mg/Kg) or acutely (20 mg/Kg) treated with DOX and sacrificed one week or 24 hours after the last injection, respectively. Alterations of mitochondrial bioenergetics showed treatment-dependent differences between tissues. No alterations were observed for cardiac mitochondria in the acute model but decreased ADP-stimulated respiration was detected in the sub-chronic treatment. In the acute treatment model, ADP-stimulated respiration was increased in liver and decreased in kidney mitochondria. Aconitase activity, a marker of oxidative stress, was decreased in renal mitochondria in the acute and in heart in the sub-chronic model. Interestingly, alterations of cardiac mitochondrial bioenergetics co-existed with an absence of echocardiograph, histopathological or ultra-structural alterations. Besides, no plasma markers of cardiac injury were found in any of the time points studied. The results confirm that alterations of mitochondrial function, which are more evident in the heart, are an early marker of DOX-induced toxicity, existing even in the absence of cardiac functional alterations

Acupuncture can be beneficial for exercise-induced muscle soreness: a randomized controlled trial.

Introduction: Strenuous physical exercise may cause acute muscle soreness (AMS), which occurs directly after exercise, as well as delayed onset muscle soreness (DOMS), which occurs about 24 h after exercise. Studies of acupuncture's effect on DOMS have had contradictory results, whereas its effect on AMS has not been extensively studied. The main goal of this study was to evaluate acupuncture's effects on AMS and DOMS and on the prevention of DOMS. Method: 45 volunteers were randomised into a verum acupuncture group, a sham acupuncture group and a control group. After exercise-induced muscle damage was elicited, muscle soreness and pressure pain threshold were assessed at different time points. The outcome assessments were performed before (T1) and 20 min after the first acupuncture treatment (T2); then, 24 h later, they were performed before (T3) and 20 min after the second acupuncture treatment (T4). In the verum and sham acupuncture groups, acupuncture was performed for 2 min, immediately after T1 and T3 assessments, whereas subjects in the control group simply rested for 2 min without treatment. Verum acupuncture was given at ST34, ST36 and LR3, whereas sham acupuncture was given at three nontraditional points. Results: We found that verum acupuncture can reduce the occurrence of AMS by one-half and DOMS by one-third. We also found specific and nonspecific acupuncture effects in AMS and DOMS. Conclusion: The uneven induction of muscle damage identified by our study, as shown by heterogeneity in pressure pain threshold values, may have led to the contradictory results in published studies on DOMS

Body and organs mass profile of animals subjected to DOX treatment protocols.

<p>Data refers to wet organ mass and its ratio to body mass was obtained dividing the organ mass over the respective total animal mass times 1000. The deceased DOX-treated rat and its matched control in the sub-chronic model were excluded from this analysis. Differences between treatment groups means within the same model were evaluated by Student’s t test (see Material and Methods for detailed information).</p>*<p>p≤0.05;</p>**<p>p≤0.01;</p>***<p>p≤0.001 vs saline group of the same treatment protocol. HM:BM – heart mass to body mass ratio; LM:BM – liver mass to body mass ratio; KM:BM – kidney mass to body mass ratio; SE – standard error.</p

Histological analysis of organs collected from rats treated with DOX.

<p>No notorious differences or hallmarks of DOX toxicity were found in the different tissues in both protocols. Panels represent HE photographs of random chosen tissues: hearts present minor cytoplasmatic vacuolization (Panel <b>B</b>) and cytoplasmatic dilatation (Panel <b>D</b>); liver usually show minor cytoplasmatic vacuolization (Panel <b>F</b> and <b>H</b>); no changes in kidneys (Panel <b>J</b> and <b>L</b>). Organs were fixed in Bouin’s solution, processed through standard histological procedures and stained with HE (for more information, see Material and Methods).</p

Blood plasma profile after DOX treatment.

#<p>For troponin I analysis, only 13 and 16 samples were measured in acute and sub-chronic protocol, respectively due to limitations in the analytical kit used.</p><p>Differences between treatment groups means within the same model were evaluated by Student’s t test, when assumptions were not achieved a Welch correction or the non-parametric Mann-Whitney test were applied (see Material and Methods for detailed information).</p>*<p>p≤0.05;</p>**<p>p≤0.01;</p>***<p>p≤0.001 vs saline group of the same model. List of abbreviations: CK – creatine kinase; TnI – troponin I; TRIG – triglycerides; CHOL – total cholesterol; AST – aspartate aminotransferase; ALT – alanine aminotransferase; TP – total serum proteins; LDH – lactate dehydrogenase; CREA – creatinine; UA – uric acid; BUN – blood urea nitrogen; SE – standard error.</p

Cellular ultra-structure remains intact after acute or sub-chronic DOX treatment.

<p>No notorious differences or hallmarks of DOX toxicity were found in the different tissues in both protocols. Panels represent electron microphotographs of randomly chosen tissues: hearts present well-defined Z-bands and organized myofibrils (Panel <b>C</b>,<b>D</b> and <b>L</b>–<b>O</b>) and minor cytoplasmatic dilatation (Panel <b>M</b> and <b>O</b>); livers show cytoplasmatic vacuolization (Panel <b>E</b>, <b>G</b> and <b>S</b>) and lipid-like droplets structures (Panel <b>Q</b>) and some mitochondria appear in the condensed conformation (Panel <b>G</b>); renal mitochondria appear in an intermediated conformation between orthodox and condensed form (Panel <b>X</b>). Organs were fixed in 4% gluteraldehyde and post-fixed in osmium (for more information, see Material and Methods).</p