Acute myocardial necrosis activates the immune response and inflammatory processes. Although the initial response is helpful in restoring tissue injury, dysregulated and exacerbated inflammation contributes to the progression of cardiac remodeling. Inflammasomes play important roles in post-infarction inflammation. NALP1/NLRP1, NLRP 3, and NLRC4 are the best-known inflammasomes. NLRP3, which has received the most study in cardiovascular disease, has been linked to increased IL-1β (IL1B) production and caspase-1 activity, as well as impaired cardiac function. The role of NLRP1 and NLRC4 inflammasomes after acute myocardial infarction (MI) is poorly understood. We evaluated the expression of myocardial inflammasomes and inflammatory markers 72 h after MI in rats. Male Wistar rats were divided into Sham (n = 15) and MI (n = 16) groups. MI was induced by ligating the left anterior descending coronary artery. Infarct size was assessed by histology. Myocardial protein and gene expression was analyzed by Western blot and RT-qPCR, respectively. IL-1β (Il1b) concentrations in serum and heart macerate supernatant were evaluated by ELISA. Statistical analysis was performed using Student’s t test. Rats with an MI size less than 30% of the total left ventricle (LV) area were excluded; infarct size was 46 ± 11% of the total LV area in MI. The interstitial collagen fraction was higher in MI. Nlrc4, caspase-1 (Casp1), and IL-1β (Il1b) protein expressions were higher in MI. Nlrp3, Nlrp1, ASC (Pycard), pro-caspase-1, and pro-IL-1β (Il1b) expressions did not differ between groups. Expression of the Nlrp3 and ASC (Pycard) genes, as well as myocardial and serum IL-1β (Il1b) concentrations, was higher in MI. Acute post-myocardial infarction inflammation is characterized by increased protein expression of Nlrc4, caspase-1, and interleukin-1β; increased gene expression of Nlrp3 and ASC (Pycard); and elevated serum and myocardial concentrations of interleukin-1β in combination with an increased myocardial collagen interstitial fraction.

Skeletal muscle changes occur in heart failure (HF). Despite the cardioprotective effects of sodium–glucose co-transporter 2 (SGLT2) inhibitors in HF, their impact on skeletal muscle remains poorly understood. We investigated the effects of the SGLT2 inhibitor empagliflozin (EMPA) on cardiac remodeling and the soleus muscle of rats with myocardial infarction (MI)-induced HF. Methods: One week after MI induction, rats were assigned to Sham, Sham + EMPA, MI, and MI + EMPA groups. EMPA was administered (5 mg/kg/day) for 12 weeks. Results: MI + EMPA and MI had dilated left cardiac chambers; the left atrium diameter and left ventricle end-diastolic area were smaller in MI + EMPA than MI. The ejection fraction did not differ between infarcted groups. MI + EMPA had a larger soleus cross-sectional area and higher Type II myosin heavy chain expression than MI. Carbonylated protein and malondialdehyde levels were lower and superoxide dismutase activity higher in MI + EMPA than MI. Respiratory Complex I expression was higher in MI + EMPA than MI. Metabolic enzyme activities, altered in MI, were normalized in MI + EMPA. EMPA up-regulated anabolic proteins and down-regulated catabolic proteins. Conclusion: Empagliflozin attenuates infarction-induced cardiac remodeling in rats. In soleus muscle, empagliflozin preserves cell trophism, reduces oxidative stress, normalizes muscle and mitochondrial metabolism, and positively modulates proteins involved in synthesis and degradation-related pathways.

Substances released by cardiomyocytes after myocardial infarction (MI) lead to inflammasome assembly. Heart failure (HF) is associated with skeletal muscle inflammation. Methotrexate (MTX) reduces cardiovascular outcomes in chronic inflammation patients. Lipid core nanoparticle-associated MTX (MTX-LDE) attenuated cardiac remodeling in MI rats. We investigated the effects of early MTX-LDE administration on cardiac remodeling and inflammasomes in soleus muscle of MI rats. Wistar rats were separated into Sham, MI, and MI-MTX groups. MTX was initiated 24 h after MI at 1 mg/kg/week intraperitoneally for 10 weeks. Soleus protein expression of NLRP1, NLRP3, NLRC4, ASC, procaspase-1, Caspase-1, pro-IL-1β, and IL-1β was quantified by Western blotting; Nlrp1a, Nlrp3, Nlrc4, Pycard (Asc), Casp1, and Il1b gene expression was assessed by qPCR; and statistical analysis used Student’s t test and ANOVA. Rats with infarction size > 35% total left ventricle (LV) area were included in the study; infarction size did not differ between groups. Echocardiogram showed infarcted groups with LV dilation and dysfunction. Diastolic function was worse in MI-MTX than MI. NLRP1 and NLRC4 protein expression was lower in MI-MTX than Sham. Expression of other proteins and gene expression did not differ between groups. Early MTX-LDE administration reduces NLRP1 and NLRC4 protein expression in soleus muscle without improving cardiac remodeling in rats.

Introduction: High-intensity interval training (HIIT) has been recommended in post-myocardial infarction (MI) cardiac rehabilitation; however, its effects on MI-induced cardiac remodeling and skeletal muscle remain unclear. This study evaluated the effects of HIIT on functional capacity, cardiac remodeling, and the soleus skeletal muscle in rats after long-term MI. Methods: Three months after MI induction, Wistar rats were assigned to Sham, MI, and MI subjected to HIIT (MI-HIIT) groups. HIIT was performed three times per week for three months on a treadmill. Cardiac function and functional capacity were assessed before and after training. Oxidative stress markers, energy metabolism enzyme activities, and trophism were analyzed in the soleus. The statistical analysis included ANOVA and Bonferroni or Kruskal–Wallis and Dunn tests. Results: HIIT improved functional capacity compared to the Sham and MI groups. The infarcted groups had left ventricular dilation, hypertrophy, and systolic dysfunction, which were not modulated by HIIT. Soleus fiber cross-sectional areas did not differ between the groups. Catalase activity was lower in the MI and MI-HIIT groups than in the Sham group, while other oxidative stress markers were unchanged. HIIT increased citrate synthase activity compared to the Sham and MI groups, and phosphofructokinase and carnitine palmitoyltransferase-1 activities compared to the MI group. Conclusions: High-intensity interval training improves functional capacity despite unchanged cardiac remodeling in long-term infarcted rats. Enhanced physical capacity is associated with the increased activity of the enzymes involved in the energy metabolism of the soleus muscle.