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Individuals with type 2 diabetes mellitus (T2DM) are at an increased risk for heart failure, yet preventive cardiac care is suboptimal in this population. Pyridoxamine (PM), a vitamin B6 analog, has been shown to exert protective effects in metabolic and cardiovascular diseases. In this study, we aimed to investigate whether PM limits adverse cardiac remodeling and dysfunction in rats who develop T2DM. Male rats received a standard chow diet or Western diet (WD) for 18 weeks to induce prediabetes. One WD group received additional PM (1 g/L) via drinking water. Glucose tolerance was assessed with a 1 h oral glucose tolerance test. Cardiac function was evaluated using echocardiography and hemodynamic measurements. Histology on left ventricular (LV) tissue was performed. Treatment with PM prevented the increase in fasting plasma glucose levels compared to WD-fed rats (p < 0.05). LV cardiac dilation tended to be prevented using PM supplementation. In LV tissue, PM limited an increase in interstitial collagen deposition (p < 0.05) seen in WD-fed rats. PM tended to decrease 3-nitrotyrosine and significantly lowered 4-hydroxynonenal content compared to WD-fed rats. We conclude that PM alleviates interstitial fibrosis and oxidative stress in the hearts of WD-induced prediabetic rats. [ABSTRACT FROM AUTHOR]

Endurance exercise training is a promising cardioprotective strategy in type 2 diabetes mellitus (T2DM), but the impact of its intensity is not clear. We aimed to investigate whether and how isocaloric moderate-intensity exercise training (MIT) and high-intensity interval exercise training (HIIT) could prevent the adverse cardiac remodeling and dysfunction that develop T2DM in rats. Male rats received a Western diet (WD) to induce T2DM and underwent a sedentary lifestyle (n = 7), MIT (n = 7) or HIIT (n = 8). Insulin resistance was defined as the HOMA-IR value. Cardiac function was assessed with left ventricular (LV) echocardiography and invasive hemodynamics. A qPCR and histology of LV tissue unraveled underlying mechanisms. We found that MIT and HIIT halted T2DM development compared to in sedentary WD rats (p < 0.05). Both interventions prevented increases in LV end-systolic pressure, wall thickness and interstitial collagen content (p < 0.05). In LV tissue, HIIT tended to upregulate the gene expression of an ROS-generating enzyme (NOX4), while both modalities increased proinflammatory macrophage markers and cytokines (CD86, TNF-α, IL-1β; p < 0.05). HIIT promoted antioxidant and dicarbonyl defense systems (SOD2, glyoxalase 1; p < 0.05) whereas MIT elevated anti-inflammatory macrophage marker expression (CD206, CD163; p < 0.01). We conclude that both MIT and HIIT limit WD-induced T2DM with diastolic dysfunction and pathological LV hypertrophy, possibly using different adaptive mechanisms. [ABSTRACT FROM AUTHOR]

Doxorubicin (DOX) is commonly used in cancer treatment but associated with cardiotoxicity. Pyridoxamine (PM), a vitamin B6 derivative, could be a cardioprotectant. This study investigated the effect of PM on DOX cardiotoxicity and DOX antitumor effectiveness. Sprague Dawley rats were treated intravenously with DOX (2 mg/kg/week) or saline over eight weeks. Two other groups received PM via oral intake (1 g/L in water bottles) next to DOX or saline. Echocardiography was performed after eight weeks. PM treatment significantly attenuated the DOX-induced reduction in left ventricular ejection fraction (72 ± 2% vs. 58 ± 3% in DOX; p < 0.001) and increase in left ventricular end-systolic volume (0.24 ± 0.02 µL/cm2 vs. 0.38 ± 0.03 µL/cm2 in DOX; p < 0.0001). Additionally, LA7 tumor cells were exposed to DOX, PM, or DOX and PM for 24 h, 48 h, and 72 h. Cell viability, proliferation, cytotoxicity, and apoptosis were assessed. DOX significantly reduced LA7 cell viability and proliferation (p < 0.0001) and increased cytotoxicity (p < 0.05) and cleaved caspase-3 (p < 0.001). Concomitant PM treatment did not alter the DOX effect on LA7 cells. In conclusion, PM attenuated DOX-induced cardiomyopathy in vivo without affecting the antitumor effect of DOX in vitro, highlighting PM as a promising cardioprotectant for DOX-induced cardiotoxicity. [ABSTRACT FROM AUTHOR]

Background: During myocardial infarction (MI), billions of cardiomyocytes are lost. The optimal therapy should effectively replace damaged cardiomyocytes, possibly with stem cells able to engraft and differentiate into adult functional cardiomyocytes. As such, cardiac atrial appendage stem cells (CASCs) are suitable candidates. However, the presence of elevated levels of advanced glycation end products (AGEs) in cardiac regions where CASCs are transplanted may affect their regenerative potential. In this study, we examine whether and how AGEs alter CASCs properties in vitro. Methods and Results: CASCs in culture were exposed to ranging AGEs concentrations (50 µg/mL to 400 µg/mL). CASCs survival, proliferation, and migration capacity were significantly decreased after 72 h of AGEs exposure. Apoptosis significantly increased with rising AGEs concentration. The harmful effects of these AGEs were partially blunted by pre-incubation with a receptor for AGEs (RAGE) inhibitor (25 µM FPS-ZM1), indicating the involvement of RAGE in the observed negative effects. Conclusion: AGEs have a time- and concentration-dependent negative effect on CASCs survival, proliferation, migration, and apoptosis in vitro, partially mediated through RAGE activation. Whether anti-AGEs therapies are an effective treatment in the setting of stem cell therapy after MI warrants further examination. [ABSTRACT FROM AUTHOR]