Ganse, F. G. | bioRxiv Science

bioRxiv2025

CERIUM OXIDE NANOPARTICLES ATTENUATE THE PRO-ARRHYTHMIC EFFECT OF DIESEL EXHAUST PARTICLES IN ISOLATED RAT HEARTS BY REDUCING OXIDATIVE STRESS.

IntroductionEpidemiological studies suggest an association between air pollution and ventricular arrhythmias, with reactive oxygen species (ROS) playing a crucial role. However, the causal relationship and long-term effects remain uncertain, and the effectiveness of interventions aimed at reducing ROS requires further investigation. AimsTo evaluate the effects of chronic exposure to diesel exhaust particles (DEPs) on ventricular arrhythmogenesis, explore the underlying mechanisms, and assess the potential of cerium oxide nanoparticles (CeO2NP) as a ROS-detoxifying intervention. MethodsSprague-Dawley rats underwent intratracheal instillation of saline without or with DEPs (7.5 g/Kg for 1-3 weeks). Ventricular arrhythmia inducibility was then assessed in isolated hearts using a protocol of programmed electrical stimulation. Cardiac hypertrophy, collagen content, inflammation and oxidative stress were analyzed using histology, Western blot, RT-PCR, and measurement of malondialdehyde content. The potential protective effects of CeO2NP (0.5 mg/Kg/week, i.p.) were also tested. ResultsDEP exposure for 3 weeks increased the incidence and duration of sustained ventricular tachyarrhythmias (VTs), a finding that correlated with a moderate increase in interstitial collagen (from 3.11{+/-}0.12% in controls to 4.80{+/-}0.21% in DEP-exposed rats, p<0.001), and an early upregulation in the expression of collagen and other fibrotic and inflammatory markers. These effects associated with prolonged QRS complex and QTc intervals, and enhanced malondialdehyde content (356.7{+/-}21.2 vs. 455.3{+/-}17.2 mol/g tissue, p=0.0066) after 3 weeks. CeO2NP treatment reduced oxidative stress and myocardial fibrosis, reversed electrocardiographic changes and attenuated DEP-induced pro-arrhythmic effects. ConclusionDEP exposure increases the incidence and duration of sustained VTs, collagen deposition and oxidative stress in rats. Treatment with CeO2NP attenuate these effects, arising as a potential novel strategy to mitigate the deleterious effects of air pollution.

pharmacology and toxicology↗

bioRxiv2024

L-lactic acid induces short- and long-term cardioprotective effects through MCT1 transport, induction of metabolic reprogramming, and gene expression modulation.

Lactic acid is recognized as an alternative fuel source for various tissues and is acknowledged for its protective effects in the brain. However, its potential as a cardioprotective agent remains controversial. Here, we aimed to (1) evaluate the impact of acute L-lactic acid administration, given at the onset of reperfusion, on myocardial infarct size in isolated mouse hearts submitted to transient global ischemia, (2) assess the effects of chronic L-lactic acid exposure in living myocardial slices (LMS) from human hearts, and (3) elucidate the underlying mechanisms. Isolated mouse hearts were submitted to global ischaemia (35 min) followed by reperfusion (60 min), with L-lactic acid being or not administered during the first 15 min of reperfusion. L-lactic acid reduced infarct size by 23% at 20 mmol/L. An acidic Krebs induced less protection, and monocarboxylate transporter 1 (MCT1) inhibition with AR-C 141990 attenuated L-lactic acids protection to the level of acidic Krebs. 1H NMR spectroscopy revealed significant metabolic changes in L-lactic acid-treated hearts, with pathway enrichment analysis showing a nearly a 3-fold enrichment in pyruvate metabolism, fatty acid biosynthesis, and gluconeogenesis, suggesting a metabolic shift. Moreover, electrically stimulated human LMS treated with L-lactic acid for 48 h exhibited improved contractility and upregulation of structural and functional cardiomyocyte components, stemness-related markers, and pro-angiogenic proteins. These findings support a cardioprotective role for L-lactic acid in both short- and long-term contexts, mediated in part by its uptake through the MCT1 transporter, induction of metabolic reprogramming, and gene expression modulation.

cell biology↗