Francisco Correa

Background: For a long time, it was thought that estrogen degradation metabolites (EDMs) had no role in the female body, but this view has changed. Despite the progress, there are still unknowns about EDMs and the heart. We found that EDMs affect isolated cardiac mitochondria, which may impact heart function. Therefore, our objective was to explore the effect of two EDMs, Met A (2-hydroxyestrone) and Met D (17β-estradiol-3-methyl-ether), on two experimental models: rat H9c2 cardiomyoblast cells exposed for increasing times to different concentrations of each EDM, and, also, the effects of each metabolite on heart function in intact and oophorectomized (Oopho) rats. Methods: The cell viability, mitochondrial potential, and oxidative stress were assayed in H9c2 cells. Echocardiographic analyses, histological analyses, and an assessment of cardiac damage and oxidative stress in intact and Oopho rats were tested. Results: The strongest negative effects were seen with Met D, where antioxidant capacity decreased and oxidative stress increased significantly. Upon further analysis of the effects of each metabolite on heart function, echocardiographic analysis revealed that cardiac function had not changed in either group, although clear signs of cardiac hypertrophy and fibrosis were observed. Conclusions: Our results suggest EDMs have specific effects on female rats. This study emphasizes the need to thoroughly investigate EDMs’ side effects and impact on the heart.

Background: Systemic arterial hypertension (SAH) induced by Nω-nitro-L-arginine methyl ester (L-NAME) is a well-established model characterized by nitric oxide (NO^●) synthase inhibition and vascular dysfunction. The transient receptor potential vanilloid 1 (TRPV1) regulates Ca²⁺ flux and may contribute to mitochondrial homeostasis. We hypothesized that TRPV1 activation modulates mitochondria function and attenuates cardiac damage during SAH. Methods: Hypertension was induced in Wistar rats by administration of L-NAME (200 mg/L) for 40 days. During the last four days, hypertensive animals received capsaicin (5 mg/kg/day), capsazepine (6 mg/kg/day), or their combination. Cardiac function was evaluated in isolated hearts using the Langendorff perfusion system. Myocardial tissue viability was assessed by triphenyltetrazolium chloride (TTC) staining, and mitochondrial function was evaluated by measuring respiratory control and apoptosis-related proteins. Results: Capsaicin treatment was associated with significant cardioprotective effects in hypertensive rats. Although the findings are consistent with a role of TRPV1 activation in mediating these effects, the partial protection observed with capsazepine suggests that TRPV1-independent mechanisms may also contribute. Conclusions: TRPV1 activation contributes to cardioprotection in SAH, likely through preservation of mitochondrial function and redox balance. However, additional mechanisms beyond TRPV1 modulation may also participate in the observed protective effects. Further studies—including direct assessment of mitochondrial Ca²⁺ flux and the use of more selective or genetic approaches—are currently underway to clarify the underlying mechanisms.

Sodium-glucose cotransporter 2 (SGLT2) inhibitor, dapagliflozin (Dapa), exhibited nephroprotective effects in patients with chronic kidney disease (CKD). We assessed the efficacy of short-term Dapa administration following acute kidney injury (AKI) in preventing CKD. Male Wistar rats were randomly assigned to Sham surgery, bilateral ischemia for 30 minutes (abbreviated as IR), and IR + Dapa groups. Daily treatment with Dapa was initiated just 24 hours after IR and maintained for only 10 days. Initially, rats were euthanized at this point to study early renal repair. After severe AKI, Dapa promptly restored creatinine clearance (CrCl) and significantly reduced renal vascular resistance compared with the IR group. Furthermore, Dapa effectively reversed the mitochondrial abnormalities, including increased fission, altered mitophagy, metabolic dysfunction, and proapoptotic signaling. To study this earlier, another set of rats was studied just 5 days after AKI. Despite persistent renal dysfunction, our data reveal a degree of mitochondrial protection. Remarkably, a 10-day treatment with Dapa demonstrated effectiveness in preventing CKD transition in an independent cohort monitored for 5 months after AKI. This was evidenced by improvements in proteinuria, CrCl, glomerulosclerosis, and fibrosis. Our findings underscore the potential of Dapa in preventing maladaptive repair following AKI, emphasizing the crucial role of early intervention in mitigating AKI long-term consequences.

Caveolae-associated signaling toward mitochondria contributes to the cardioprotective mechanisms against ischemia-reperfusion (I/R) injury induced by ischemic postconditioning. In this work, we evaluated the role that the actin-cytoskeleton network exerts on caveolae-mitochondria communication during postconditioning. Isolated rat hearts subjected to I/R and to postconditioning were treated with latrunculin A, a cytoskeleton disruptor. Cardiac function was compared between these hearts and those exposed only to I/R and to the cardioprotective maneuver. Caveolae and mitochondria structures were determined by electron microscopy and maintenance of the actin-cytoskeleton was evaluated by phalloidin staining. Caveolin-3 and other putative caveolae-conforming proteins were detected by immunoblot analysis. Co-expression of caveolin-3 and actin was evaluated both in lipid raft fractions and in heart tissue from the different groups. Mitochondrial function was assessed by respirometry and correlated with cholesterol levels. Treatment with latrunculin A abolishes the cardioprotective postconditioning effect, inducing morphological and structural changes in cardiac tissue, reducing F-actin staining and diminishing caveolae formation. Latrunculin A administration to post-conditioned hearts decreases the interaction between caveolae-forming proteins, the co-localization of caveolin with actin and inhibits oxygen consumption rates in both subsarcolemmal and interfibrillar mitochondria. We conclude that actin-cytoskeleton drives caveolae signaling to mitochondria during postconditioning, supporting their functional integrity and contributing to cardiac adaption against reperfusion injury.

Mitochondrial permeability transition is characterized by the opening of a transmembranal pore that switches membrane permeability from specific to nonspecific. This structure allows the free traffic of ions, metabolites, and water across the mitochondrial inner membrane. The opening of the permeability transition pore is triggered by oxidative stress along with calcium overload. In this work, we explored if oxidative stress is a consequence, rather than an effector of the pore opening, by evaluating the interaction of agaric acid with the adenine nucleotide translocase, a structural component of the permeability transition pore. We found that agaric acid induces transition pore opening, increases the generation of oxygen-derived reactive species, augments the oxidation of unsaturated fatty acids in the membrane, and promotes the detachment of cytochrome c from the inner membrane. The effect of agaric acid was inhibited by the antioxidant tamoxifen in association with decreased binding of the thiol reagent eosin-3 maleimide to the adenine nucleotide translocase. We conclude that agaric acid promotes the opening of the pore, increasing ROS production that exerts oxidative modification of critical thiols in the adenine nucleotide translocase.

Cytidine‐5'‐diphosphocholine (CDP‐choline) participates as an intermediary in the synthesis of phosphatidylcholine, an essential component of cellular membranes. Citicoline treatment has shown beneficial effects in cerebral ischemia, but its potential to diminish reperfusion damage in liver has not been explored. In this work, we evaluated the hepatoprotective effect of citicoline and its possible association with inflammatory/oxidative stress and mitochondrial function because they are the main cellular features of reperfusion damage. Ischemia/reperfusion (I/R) in rat livers was performed with the Pringle's maneuver, clamping the 3 elements of the pedicle (hepatic artery, portal vein, and biliary tract) for 30 minutes and then removing the clamp to allow hepatic reperfusion for 60 minutes. The I/R + citicoline group received the compound before I/R. Liver injury was evaluated by measuring aspartate aminotransferase and alanine aminotransferase as well as lactic acid levels in serum; proinflammatory cytokines, proresolving lipid mediators, and nuclear factor kappa B content were determined as indicators of the inflammatory response. Antioxidant effects were evaluated by measuring markers of oxidative stress and antioxidant molecules. Oxygen consumption and the activities of the respiratory chain were used to monitor mitochondrial function. CDP‐choline reduced aspartate aminotransferase (AST), alanine aminotransferase (ALT), as well as lactic acid levels in blood samples from reperfused rats. Diminution in tumor necrosis factor alpha (TNF‐α) and increase in the proresolving lipid mediator resolvin D1 were also observed in the I/R+citicoline group, in comparison with the I/R group. Oxidative/nitroxidative stress in hepatic mitochondria concurred with deregulation of oxidative phosphorylation, which was associated with the loss of complex III and complex IV activities. In conclusion, CDP‐choline attenuates liver damage caused by ischemia and reperfusion by reducing oxidative stress and maintaining mitochondrial function. Liver Transplantation XX XX‐XX 2018 AASLD.

We addressed if oxidative stress in the renal cortex plays a role in the induction of hypertension and mitochondrial alterations in hyperuricemia. A second objective was to evaluate whether the long-term treatment with the antioxidant Tempol prevents renal oxidative stress, mitochondrial alterations, and systemic hypertension in this model. Long-term (11-12 weeks) and short-term (3 weeks) effects of oxonic acid induced hyperuricemia were studied in rats (OA, 750 mg/kg BW), OA+Allopurinol (AP, 150 mg/L drinking water), OA+Tempol (T, 15 mg/kg BW), or vehicle. Systolic blood pressure, renal blood flow, and vascular resistance were measured. Tubular damage (urine N-acetyl-β-D-glucosaminidase) and oxidative stress markers (lipid and protein oxidation) along with ATP levels were determined in kidney tissue. Oxygen consumption, aconitase activity, and uric acid were evaluated in isolated mitochondria from renal cortex. Short-term hyperuricemia resulted in hypertension without demonstrable renal oxidative stress or mitochondrial dysfunction. Long-term hyperuricemia induced hypertension, renal vasoconstriction, tubular damage, renal cortex oxidative stress, and mitochondrial dysfunction and decreased ATP levels. Treatments with Tempol and allopurinol prevented these alterations. Renal oxidative stress induced by hyperuricemia promoted mitochondrial functional disturbances and decreased ATP content, which represent an additional pathogenic mechanism induced by chronic hyperuricemia. Hyperuricemia-related hypertension occurs before these changes are evident.

Authors: Sauri Hernández-Reséndiz, Mabel Buelna-Chontal, Francisco Correa and Cecilia Zazueta

Background and purpose: The mitochondrial permeability transition pore (mPTP), an energy‐dissipating channel activated by calcium, contributes to reperfusion damage by depolarizing the mitochondrial inner membrane potential. As mitochondrial Ca²⁺ overload is a main inductor of mPTP opening, we examined the effect of Ru₃₆₀, a selective inhibitor of the mitochondrial calcium uptake system against myocardial damage induced by reperfusion in a rat model.Experimental approach: Myocardial reperfusion injury was induced by a 5‐min occlusion of the left anterior descending coronary artery, followed by a 5‐min reperfusion in anaesthetized open‐chest rats. We measured reperfusion‐induced arrhythmias and functions indicative of unimpaired mitochondrial integrity to evaluate the effect of Ru₃₆₀ treatment.Key results: Reperfusion elicited a high incidence of arrhythmias, haemodynamic dysfunction and loss of mitochondrial integrity. A bolus intravenous injection of Ru₃₆₀ (15‐50 nmol kg⁻¹), given 30‐min before ischaemia, significantly improved the above mentioned variables in the ischaemic/reperfused myocardium. Calcium uptake in isolated mitochondria from Ru₃₆₀‐treated ventricles was partially diminished, suggesting an interaction of this compound with the calcium uniporter.Conclusions and implications: We showed that Ru₃₆₀ treatment abolishes the incidence of arrhythmias and haemodynamic dysfunction elicited by reperfusion in a whole rat model. Ru₃₆₀ administration partially inhibits calcium uptake, preventing mitochondria from depolarization by the opening of the mPTP. We conclude that myocardial damage could be a consequence of failure of the mitochondrial network to maintain the membrane potential at reperfusion. Hence, it is plausible that Ru₃₆₀ could be used in reperfusion therapy to prevent the occurrence of arrhythmia.British Journal of Pharmacology (2006) 149, 829–837. doi:10.1038/sj.bjp.0706932