Resistance training prevents right ventricle hypertrophy in rats exposed to secondhand cigarette smoke

Altered skeletal muscle function and beneficial effects of exercise training in a rat model of induced pulmonary emphysema

AIM

Chronic obstructive pulmonary disease (COPD) is characterized by progressive airflow obstruction and development of emphysema. Among the comorbidities associated with COPD, skeletal muscle dysfunction is known to affect exercise capacity and the survival rate of patients. Pulmonary rehabilitation (PR), via exercise training, is essential for COPD patients. However, the response to PR is most often moderate. An animal model that recapitulates critical features of chronic human disease and provides access to muscle function should therefore be useful to improve PR benefits.

METHODS

We used a rat model of induced emphysema based on pulmonary instillations of elastase (ELA) and lipopolysaccharides (LPS). We assessed the long-term effects of ELA/LPS and the potential effectiveness of endurance training on the skeletal muscle function. In vivo strength of the animals, and ex vivo contractility, endurance, type 1 fiber proportion, fiber cross-sectional area, and capillarization of both soleus and extensor digitorum longus (EDL) were assessed.

RESULTS

An impaired overall muscle strength with decreased force, reduced capillarization, and atrophy of type 1 fiber of EDL was observed in ELA/LPS rats. Soleus was not affected. Endurance training was able to reduce fatigability, and increase type 1 fiber proportion and capillarization of soleus, and improve force, endurance, and capillarization of EDL in control and ELA/LPS rats.

CONCLUSION

Our rat model of induced emphysema, which shares some features with the phenotype present in patients with COPD, could represent a suitable model to study skeletal muscle dysfunction and the effects of exercise training on muscle function in patients.

Resistance training prevents damage to the mitochondrial function of the skeletal muscle of rats exposed to secondary cigarette smoke

AIM

To analyze the consumption of oxygen and to quantify the mitochondrial respiratory chain proteins (OXPHOS) in the gastrocnemius muscle of rats exposed to cigarette smoke and/or RT practitioners.

MAIN METHODS

Wistar rats were divided into groups: Control (C), Smoker (S), Exercise (E) and Exercise Smoker (ES). Groups F and ES were exposed to the smoke of 4 cigarettes for 30 min, 2× a day, 5× a week, for 16 weeks. Groups E and ES performed four climbs with progressive load, 1× per day, 5× per week, for 16 weeks. The gastrocnemius muscle was collected for analysis of OXPHOS content and oxygen consumption. Groups S (vs. C) and ES (vs. C and E) showed lower body weight gain when observing the evolution curve.

KEY FINDINGS

The S rats showed a reduction in the NDUFB8 proteins of complex 1, SDHB of complex 2, MTC01 of complex 4 and ATP5A of complex 5 (ATP Synthase) compared to Group C. Additionally, S rats also showed increased consumption of O2 in Basal, Leak, Complex I and I/II combined measures compared to the other groups, suggesting that the activity of the mitochondria of these animals increased in terms of coupling and uncoupling parameters.

SIGNIFICANCE

Our data suggest that exposure to cigarette smoke for 16 weeks is capable of causing impairment of mitochondrial function with reduced expression of respiratory chain proteins in skeletal muscle. However, the RT was effective in preventing impairment of mitochondrial function in the skeletal muscle of rats exposed to secondary cigarette smoke.

E-cigarette exposure with or without heating the e-liquid induces differential remodeling in the lungs and right heart of mice

Various cardiopulmonary pathologies associated with electronic cigarette (EC) vaping have been reported. This study investigated the differential adverse effects of heating-associated by-products versus the intact components of EC aerosol to the lungs and heart of mice. We further dissected the roles of caspase recruitment domain-containing protein 9 (CARD9)-associated innate immune response and NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome in EC exposure-induced cardiopulmonary injury. C57BL/6 wild type (WT), CARD9^-/-, and NLRP3^-/- mice were exposed to EC aerosol 3 h/day, 5 days/week for 6 month with or without heating the e-liquid with exposure to ambient air as the control. In WT mice, EC exposure with heating (EwH) significantly increased right ventricle (RV) free wall thickness at systole and diastole. However, EC exposure without heating (EwoH) caused a significant decrease in the wall thickness at systole. RV fractional shortening was also markedly reduced following EwH in WT and NLRP3^-/- mice. Further, EwH activated NF-κB and p38 MAPK inflammatory signaling in the lungs, but not in the RV, in a CARD9- and NLRP3-dependent manner. Levels of circulatory inflammatory mediators were also elevated following EwH, indicating systemic inflammation. Moreover, EwoH activated TGF-β1/SMAD2/3/α-SMA fibrosis signaling in the lungs but not the RV of WT mice. In conclusion, EC aerosol exposure following EwH or EwoH induced differential cardiopulmonary remodeling and CARD9 innate immune and NLRP3 inflammasome contributed to the adverse effects.

Resistance training mitigates hepato-cardiac changes and muscle mitochondrial protein reductions in rats with diet-induced obesity

Aim

To investigate the effect of resistance training (RT) on hepatocardiovascular and muscle mitochondrial parameters in rats that were fed a high-calorie diet for 12 weeks.

Main methods

The animals were divided into four groups: control (C), exercise (E), obese (O), and obese plus exercise (OE). Group E and OE rats performed resistance training by climbing on a vertical ladder with load attached to the end of the tail (1×/day, 3×/week, for 12 weeks). Group O and OE rats were fed a high-calorie diet containing chow and a cafeteria diet for 12 weeks. Under anesthesia, the heart and liver were removed for histopathological analysis, and the gastrocnemius muscle was removed for Western blotting.

Key findings

Group O rats were heavier, with increased fat mass, elevated fasting glycemia, and total triglycerides, and exhibited a significant number of Kupffer cells and diffuse steatosis in the liver. Group O rats also showed increased thickness of the right ventricle, septum, and pulmonary artery. All of these parameters were attenuated by RT. PGC1-α protein levels were increased in both exercise groups. The protein levels of OXPHOS complexes III, IV, and V were reduced in Group O, while RT prevented this alteration.

Significance

RT exerts a protective effect against hepato-cardiac alterations and prevents changes in the muscle mitochondrial protein profile induced by a high-calorie diet.

Physical Activity in Polluted Air-Net Benefit or Harm to Cardiovascular Health? A Comprehensive Review

Both exposure to higher levels of polluted air and physical inactivity are crucial risk factors for the development and progression of major noncommunicable diseases and, in particular, of cardiovascular disease. In this context, the World Health Organization estimated 4.2 and 3.2 million global deaths per year in response to ambient air pollution and insufficient physical activity, respectively. While regular physical activity is well known to improve general health, it may also increase the uptake and deposit of air pollutants in the lungs/airways and circulation, due to increased breathing frequency and minute ventilation, thus increasing the risk of cardiovascular disease. Thus, determining the tradeoff between the health benefits of physical activity and the potential harmful effects of increased exposure to air pollution during physical activity has important public health consequences. In the present comprehensive review, we analyzed evidence from human and animal studies on the combined effects of physical activity and air pollution on cardiovascular and other health outcomes. We further report on pathophysiological mechanisms underlying air pollution exposure, as well as the protective effects of physical activity with a focus on oxidative stress and inflammation. Lastly, we provide mitigation strategies and practical recommendations for physical activity in areas with polluted air.