ABSTRACT
OBJECTIVE: While prolonged sedentary behaviors (SBs) increase cardiovascular disease (CVD) risk, interrupting prolonged sitting (PS) with frequent light exercise reduces arterial functional decline. Skeletal muscle electrical stimulation (EMS) enhances peripheral circulation through passive muscle contraction, suggesting that EMS reduces CVD risk by providing an alternative to active exercise for prolonged SBs. This study aimed to investigate the effects of EMS to skeletal muscles during PS on the endothelial function of the brachial artery (BA). METHODS: Study participants included 12 healthy adult men who were subjected to 15 min of supine rest, followed by 1 h of PS only (control [CON] trial), or 20 min of EMS to the lower extremities at 50% of the maximum tolerance intensity during PS (EMS trial). Flow-mediated dilation (FMD) of the BA was measured before and 30 min after PS, and normalized FMD (nFMD) was calculated. RESULTS: The nFMD of the CON trial significantly decreased 30 min after PS completion (6.21% ± 1.13%) compared with that before PS (7.26% ± 0.73%), and there was no significant change in the EMS trial before and after PS. The EMS trial showed a significant increase in the nFMD 30 min after PS completion (1.14 ± 0.77) compared with that before PS (0.84 ± 0.43). However, no significant difference was observed in the CON trials. CONCLUSION: Passive contraction of the lower extremity muscles by EMS increases BA nFMD, suggesting that prolonged sedentary lower extremity EMS use may reduce the risk of vascular endothelial dysfunction.
ABSTRACT
This study aimed to determine whether arm-cranking training with electrical muscle stimulation (EMS) results in a greater improvement in vessel function than performing the same exercise without EMS. First, nine healthy young men performed two 20-min arm-cranking trials at 50% VËO2max with and without EMS applied to the lower limbs. The flow-mediated vasodilation (FMD) of the right brachial artery was measured using a high-resolution ultrasound device. Both FMD and normalized FMD were increased significantly after the arm-cranking with EMS trial, and significant differences were observed between the two trials. Second, 16 healthy adult men were randomly assigned to either the arm-cranking exercise training (A) group or arm-cranking training with EMS (A+EMS) group. The subjects were engaged in 20 min of arm-cranking at 50% VËO2max twice a week for 8 weeks with/without EMS applied to the lower limbs. The FMD increased significantly after A+EMS training session and the FMD in A+EMS group was significantly higher than that in the A group. These results indicate that acute/chronic endurance arm-cranking with EMS applied to the lower limbs improves the brachial artery endothelial function more markedly than the same exercise without EMS.
Subject(s)
Arm , Brachial Artery , Electric Stimulation , Exercise , Vasodilation , Adult , Brachial Artery/physiology , Humans , Lower Extremity , Male , MusclesABSTRACT
Many businesses thrive by producing health supplements from agricultural products, as exemplified by the production of functional (or health) foods using plants traditionally cultivated in rural areas. Dyes, such as indican, indigo, indoxyl, and indirubin, present in dye plants, possess antibacterial, antifungal, and antiproliferative activities. However, these effects may also lead to cytotoxicity. Thus, studies on normal mammalian cells are necessary to identify cytotoxicity and prevent adverse effects of functional foods that contain these dyes. In this study, the effects of indican, indigo, indoxyl, and indirubin were evaluated by flow cytometry using appropriate fluorescent probes in rat thymic lymphocytes. Among the dyes analyzed, indirubin exerted distinct cellular activities. Treatment with indirubin (10-30 µM) increased the population of shrunken dead cells. The side scatter, but not forward scatter, increased in indirubin-treated living cells. It increased the population of annexin V-bound living and dead cells and that of dead cells without annexin V. Indirubin elevated intracellular Ca2+, but not Zn2+ levels. The cellular content of superoxide anions increased and that of glutathione decreased. Indirubin depolarized the cellular plasma and mitochondrial membranes. It did not potentiate or attenuate the cytotoxicity of A23187 (Ca2+ overload) and H2O2 (oxidative stress). The results suggested that indirubin induces both apoptotic and non-apoptotic cell death. It may be difficult to predict and prevent the adverse effects of indirubin due to its diverse activities on normal mammalian cells. Therefore, indirubin should be removed from products that contain dye plant extracts.
ABSTRACT
2,2-Dibromo-3-nitrilopropionamide (DBNPA) is a major biocide in hydraulic fracturing fluids. Most biocides in fracturing fluids are considered to have low acute toxicity to mammals, but little information is available in the literature regarding the toxic actions of DBNPA on mammalian cells. This information is important to suggest the DBNPA toxicity on wild mammals. In this study, the effects of DBNPA on rat thymocytes were studied using flow cytometric techniques in order to further characterize the cytotoxicity of DBNPA for its safe use. DBNPA at 3-7.5 µM produced a steep concentration-dependent increase in cell lethality. At 5 µM, DBNPA significantly depolarized the membranes with a disturbance of the asymmetrical distribution of membrane phospholipids. The lethal effect of DBNPA was completely abolished under cold conditions, and was augmented in the presence of ethanol. It is suggested that the lethal action of DBNPA is linked to changes in membrane fluidity. Because the concentration-dependent change of DBNPA-induced lethal action was very steep under in vitro conditions, the adverse actions of DBNPA on wild mammals are concerning, even though such reports have not yet surfaced.
