Moderate-Intensity and High-Intensity Interval Exercise Training Offer Equal Cardioprotection, with Different Mechanisms, during the Development of Type 2 Diabetes in Rats

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.

Pyridoxamine Attenuates Doxorubicin-Induced Cardiomyopathy without Affecting Its Antitumor Effect on Rat Mammary Tumor Cells

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.

Heart failure is associated with accelerated age related metabolic bone disease

BACKGROUND

The heart failure (HF)-syndrome is associated with neuro-hormonal activation, chronic kidney disease (CKD), inflammation and alterations in the phosphorus-metabolism, all of which are involved in regulation of mineral bone density. However, the role of HF as an independent factor associated with metabolic bone disease (MBD) remains unclear.

METHODS

HF-patients undergoing dual X-ray absorptiometry (DEXA) were matched in a 1:2 fashion against age and gender matched controls without HF, to determine the proportion of osteoporosis (T-score < -2.5). HF-status was tested against known predictors of MBD. Correlation analysis and Z-score analysis were used to assess the impact of HF on age-related bone demineralisation.

RESULTS

A total of 190 HF-patients (age = 80 ± 10 years, female = 61%) were age and gender matched to 380 controls. HF-patients had a higher proportion of osteoporosis (26 vs 17%; p = .007). HF patients had a lower averaged mineral bone density expressed in g/cm² (p = .030), T-scores (p = .001) and Z-scores (p < .001). After adjusting for the individual osteoporosis risk-factors of the FRAX-score, difference in baseline features, kidney function and phosphorus-metabolism alterations, heart failure remained independently associated with a lower averaged T-score (Adjusted β = -0.189; p = .017). Heart failure was associated with an accelerated age-related decline in mineral bone density (p = .0418). Therapies with ACE-I or ARBs and beta-blockers associated with ameliorated bone demineralisation (p = .023, respectively p = .029), while loop diuretic associated with worsened bone demineralization (p < .001).

CONCLUSION

Heart failure independently associates with MBD and higher prevalence of osteoporosis. Heart failure aggravates the aged related loss in mineral bone density while treatment with neuro-hormonal blockers seemed to ameliorate this finding.