Frontiers in physiology
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Frontiers in physiology · Jan 2018
Dexamethasone Protects Against Tourniquet-Induced Acute Ischemia-Reperfusion Injury in Mouse Hindlimb.
Extremity injuries with hemorrhage have been a significant cause of death in civilian medicine and on the battlefield. The use of a tourniquet as an intervention is necessary for treatment to an injured limb; however, the tourniquet and subsequent release results in serious acute ischemia-reperfusion (IR) injury in the skeletal muscle and neuromuscular junction (NMJ). Much evidence demonstrates that inflammation is an important factor to cause acute IR injury. ⋯ Treatment with dexamethasone at the beginning of reperfusion (1 mg/kg, i.p.) significantly inhibited expression of TNFα and IL-1β, reduced rupture of the muscle sarcolemma and infarct size (24.8 ± 2.0%), and improved direct muscle stimulation-induced gastrocnemius muscle contraction in 24-h IR mice. However, this anti-inflammatory drug did not improve NMJ morphology and function, and sciatic nerve-stimulated skeletal muscle contraction in 24-h IR mice. The data suggest that one-time treatment with dexamethasone at the beginning of reperfusion only reduced structural and functional impairments of the skeletal muscle but not the NMJ through inhibiting inflammatory cytokines.
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Frontiers in physiology · Jan 2018
Cerebrovascular Reactivity and Central Arterial Stiffness in Habitually Exercising Healthy Adults.
Reduced cerebrovascular reactivity to a vasoactive stimulus is associated with age-related diseases such as stroke and cognitive decline. Habitual exercise is protective against cognitive decline and is associated with reduced stiffness of the large central arteries that perfuse the brain. In this context, we evaluated the age-related differences in cerebrovascular reactivity in healthy adults who habitually exercise. ⋯ There were no associations between PWV and cerebrovascular reactivity (range: r = 0.00-0.39; p = 0.07-0.99). Our results demonstrate that cerebrovascular reactivity was not different between young and older adults who habitually exercise; however, MAP reactivity was augmented in older adults. This suggests an age-associated difference in the reliance on MAP to increase cerebral blood flow during hypercapnia.
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Frontiers in physiology · Jan 2018
Impact of Different Tidal Volume Levels at Low Mechanical Power on Ventilator-Induced Lung Injury in Rats.
Tidal volume (VT) has been considered the main determinant of ventilator-induced lung injury (VILI). Recently, experimental studies have suggested that mechanical power transferred from the ventilator to the lungs is the promoter of VILI. We hypothesized that, as long as mechanical power is kept below a safe threshold, high VT should not be injurious. ⋯ Multiple linear regression analyses indicated that VT was able to predict changes in IL-6 and CC16, whereas ΔP,L predicted pHa, oxygenation, amphiregulin, and syndecan-1 expression. In the model of ARDS used herein, even at low mechanical power, high VT resulted in VILI. VT control seems to be more important than RR control to mitigate VILI.
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Frontiers in physiology · Jan 2018
Effects of an Eight-Week Superimposed Submaximal Dynamic Whole-Body Electromyostimulation Training on Strength and Power Parameters of the Leg Muscles: A Randomized Controlled Intervention Study.
The purpose of this study was to assess the effects of dynamic superimposed submaximal whole-body electromyostimulation (WB-EMS) training on maximal strength and power parameters of the leg muscles compared with a similar dynamic training without WB-EMS. Eighteen male sport students were randomly assigned either to a WB-EMS intervention (INT; n = 9; age: 28.8 (SD: 3.0) years; body mass: 80.2 (6.6) kg; strength training experience: 4.6 (2.8) years) or a traditional strength training group (CON; n = 9; age: 22.8 (2.5) years; body mass: 77.6 (9.0) kg; strength training experience: 4.5 (2.9) years). Both training intervention programs were performed twice a week over a period of 8 weeks with the only difference that INT performed all dynamic exercises (e.g., split squats, glute-ham raises, jumps, and tappings) with superimposed WB-EMS. ⋯ A significant time × group interaction effect was merely observed for Fmax on the LE where follow-up post hoc testing showed significantly higher improvements in the INT group from PRE to POST and PRE to FU (INT: +7.7%, p < 0.01; CON: +2.1%). These findings indicate that the combination of dynamic exercises and superimposed submaximal WB-EMS seems to be effective in order to improve leg strength and power. However, in young healthy adults the effects of superimposed WB-EMS were similar to the effects of dynamic resistance training without EMS, with the only exception of a significantly greater increase in leg extension Fmax in the WB-EMS group.