Intensity of swimming exercise influences tracheal reactivity in rats

Lactate thresholds and role of nitric oxide in male rats performing a test with forced swimming to exhaustion

The present study assessed a complex of biochemical parameters at the anaerobic threshold (AT) in untrained male Wistar rats with different times to exhaustion (Tex ) from swimming. The first group of rats was randomly divided into six subgroups and subjected to a swimming test to exhaustion without a load or with a load of 2%-10% of body weight (BW). In the first group, we established that for untrained rats, the load of 4% BW in the swimming to exhaustion test was optimal for endurance assessment in comparison with other loads. The second group of rats went through a preliminary test with swimming to exhaustion at 4% BW and was then divided into two subgroups: long swimming time (LST, Tex  > 240 min) and short swimming time (SST, Tex  < 90 min). All rats of the second group performed, for 6 days, an experimental training protocol: swimming for 20 min each day with weight increasing each day. We established that the AT was 3% BW in SST rats and 5% BW in LST rats. The AT shifted to the right on the lactate curve in LST rats. Also, at the AT in the LST rats, we found significantly lower levels of blood lactate, cortisol, and NO.

Modeling exercise using optogenetically contractible Drosophila larvae

The pathophysiological effects of a number of metabolic and age-related disorders can be prevented to some extent by exercise and increased physical activity. However, the molecular mechanisms that contribute to the beneficial effects of muscle activity remain poorly explored. Availability of a fast, inexpensive, and genetically tractable model system for muscle activity and exercise will allow the rapid identification and characterization of molecular mechanisms that mediate the beneficial effects of exercise. Here, we report the development and characterization of an optogenetically-inducible muscle contraction (OMC) model in Drosophila larvae that we used to study acute exercise-like physiological responses. To characterize muscle-specific transcriptional responses to acute exercise, we performed bulk mRNA-sequencing, revealing striking similarities between acute exercise-induced genes in flies and those previously identified in humans. Our larval muscle contraction model opens a path for rapid identification and characterization of exercise-induced factors.

Supplementation With Spirulina platensis Improves Tracheal Reactivity in Wistar Rats by Modulating Inflammation and Oxidative Stress

Spirulina platensis has shown effectiveness in the treatment of allergic rhinitis in rats, but its action in tracheal reactivity or on markers of relaxation and antioxidant profile has not yet been possible to determine. In this paper, the animals were divided into the groups healthy (SG) and supplemented with S. platensis at doses of 50 (SG50), 150 (SG150), and 500 mg/kg (SG500). We also evaluated nitrite levels, lipid peroxidation, and antioxidant activity through biochemical analysis. For contractile reactivity, only SG500 (pEC50 = 5.2 ± 0.06 showed reduction in carbachol contractile potency. Indomethacin caused a higher contractile response to carbachol in SG150 and SG500. For relaxation, curves for SG150 (pEC50 = 5.0 ± 0.05) and SG500 (pEC50 = 7:3 ± 0:02) were shifted to the left, more so in SG500. We observed an increase in nitrite in the trachea only with supplementation of 500 mg/kg (54.0 ± 8.0 µM), also when compared to SG50 (37.0 ± 10.0 µM) and SG150 (38.0 ± 7.0 µM). We observed a decrease in lipid peroxidation in the plasma and an increase in oxidation inhibition for the trachea and lung in SG150 and SG500, suggesting enhanced antioxidant activity. S. platensis (150/500 mg/kg) decreased the contractile response and increased relaxation by increasing antioxidant activity and nitrite levels and modulating the inflammatory response.

Effects of Succinate-Containing Preparation on Characteristics of Rat Erythrocytes in Exhaustive Swimming with a Load

We studied the dynamics of the red blood cell composition of Wistar male rats at rest and when swimming with a load (4% body weight) before and after administration of a succinatecontaining preparation (meso-2,3-dimercaptosuccinic acid). In rats receiving the succinatecontaining preparation, a decrease in the number of red blood cells and an increase in their volume and absolute and relative number of reticulocytes were observed at rest in comparison with vivarium control. In rats exposed to exhaustive swimming after preliminary administration of the test preparation (12 h before the test), we observed a decrease in hematocrit and erythrocyte diameter in comparison with the corresponding parameters in rats not treated with the preparation; the level of hemoglobin did not change. The pattern of changes in the cellular composition of red blood in rats at rest and during swimming against the background of treatment with the succinate-containing preparation in comparison with vivarium control is considered as a result of its effect on physical exercise under conditions of stabilization of hemoglobin and hematocrit levels, activation of proliferative activity of red bone marrow, and an increase in time of swimming to exhaustion by 2.8 times.

Contribution of angiotensin II in hepatic ischemia /reperfusion induced lung injury: Acute versus chronic usage of captopril

BACKGROUND

Acute lung injury is one of the most popular consequences of hepatic ischemia/reperfusion (I/R) injury. Recently it was documented that renin-angiotensin system plays a key role in tissue inflammation, generation of reactive oxygen species (ROS) and tumor necrosis factor-alpha (TNF-α) (the principal liver injury mediators) during I/R.

MATERIAL AND METHODS

We investigated the effect of acute versus chronic usage of angiotensin converting enzyme inhibitor (captopril) on liver inflammation and lung injury caused by hepatic ischemia for 1h followed by 24h reperfusion. Forty adult Wistar male rats were divided into sham, I/R, I/R-acute captopril (100 mg/kg, 24 and 1.5 h before surgery) and I/R-chronic captopril (10 mg/kg/day for 28 days before surgery) groups.

RESULTS

We found captopril pretreatment significantly decreased liver damage indices, adhesion molecules, and TNF-α level in hepatic and tracheal tissues. Histologically, acute captopril pretreatment significantly decreased hepatic Kupffer cells number and lung α-smooth muscle actin expression more than chronic pretreatment. Increased tracheal tone, in response to acetylcholine, was suppressed by acute and chronic captopril pretreatment.

CONCLUSION

Angiotensin II plays a key role in tissue inflammation and airway hyperresponsiveness (AHR) via enhancing production of TNF-α. With more protection observed in lung, acute captopril could attenuate liver-induced lung injury via lowering TNF-α; a suggested possible mediator of airway hyperreactivity.

Exercise-Induced Regulation of Redox Status in Cardiovascular Diseases: The Role of Exercise Training and Detraining

Although low levels of reactive oxygen species (ROS) are beneficial for the organism ensuring normal cell and vascular function, the overproduction of ROS and increased oxidative stress levels play a significant role in the onset and progression of cardiovascular diseases (CVDs). This paper aims at providing a thorough review of the available literature investigating the effects of acute and chronic exercise training and detraining on redox regulation, in the context of CVDs. An acute bout of either cardiovascular or resistance exercise training induces a transient oxidative stress and inflammatory response accompanied by reduced antioxidant capacity and enhanced oxidative damage. There is evidence showing that these responses to exercise are proportional to exercise intensity and inversely related to an individual’s physical conditioning status. However, when chronically performed, both types of exercise amplify the antioxidant defense mechanism, reduce oxidative stress and preserve redox status. On the other hand, detraining results in maladaptations within a time-frame that depends on the exercise training intensity and mode, as high-intensity training is superior to low-intensity and resistance training is superior to cardiovascular training in preserving exercise-induced adaptations during detraining periods. Collectively, these findings suggest that exercise training, either cardiovascular or resistance or even a combination of them, is a promising, safe and efficient tool in the prevention and treatment of CVDs.