Post-exercise hypotension (PEH), calculated by the difference between post and pre-exercise values, it is greater after exercise performed in the evening than the morning. However, the hypotensive effect of morning exercise may be masked by the morning circadian increase in blood pressure. This study investigated PEH and its hemodynamic and autonomic mechanisms after sessions of aerobic exercise performed in the morning and evening, controlling for responses observed after control sessions performed at the same times of day. Sixteen pre-hypertensive men underwent four sessions (random order): two conducted in the morning (7:30am) and two in the evening (5pm). At each time of day, subjects underwent an exercise (cycling, 45 min, 50%VO2peak) and a control (sitting rest) session. Measurements were taken pre- and post-interventions in all the sessions. The net effects of exercise were calculated for each time of day by [(post-pre exercise)-(post-pre control)] and were compared by paired t-test (P<0.05). Exercise hypotensive net effects (e.g., decreasing systolic, diastolic and mean blood pressure) occurred at both times of day, but systolic blood pressure reductions were greater after morning exercise (-7±3 vs. -3±4 mmHg, P<0.05). Exercise decreased cardiac output only in the morning (-460±771 ml/min, P<0.05), while it decreased stroke volume similarly at both times of day and increased heart rate less in the morning than in the evening (+7±5 vs. +10±5 bpm, P<0.05). Only evening exercise increased sympathovagal balance (+1.5±1.6, P<0.05) and calf blood flow responses to reactive hyperemia (+120±179 vs. -70±188 U, P<0.05). In conclusion, PEH occurs after exercise conducted at both times of day, but the systolic hypotensive effect is greater after morning exercise when circadian variations are considered. This greater effect is accompanied by a reduction of cardiac output due to a smaller increase in heart rate and cardiac sympathovagal balance.
Introduction:The acute blood pressure (BP) decrease is greater after evening than morning exercise, suggesting that evening training may have a greater hypotensive effect. Objective:To compare the hypotensive effect of aerobic training performed in the morning versus evening in treated hypertensives. Methods: Fifty treated hypertensive men were randomly allocated to 3 groups: morning training (MT); evening training (ET); and control (C). Training groups cycled for 45min at moderate-intensity (progressing from the heart rate of the anaerobic threshold to 10% below the heart rate of the respiratory compensation point), while C stretched for 30 min. Interventions were conducted 3 times/week for 10 weeks. Clinic and ambulatory BP, hemodynamic, and autonomic mechanisms were evaluate d before and after the interventions. Clinic assessments were performed in the morning (7-9a.m.) and evening (6-8p.m.). Between-within ANOVAs were used (P≤0.05). Results: Only ET decreased clinic systolic BP differently from C and MT (morning assessment -5±6 mmHg and evening assessment -8±7 mmHg, P<0.05). Only ET reduced 24h and asleep diastolic BP differently from C and MT (-3±5 and -3±4 mmHg, respectively, P<0.05). Systemic vascular resistance (SVR) decreased from C only in ET (P=0.03). Vasomotor sympathetic modulation decreased (P=0.001) and baroreflex sensitivity (P<0.02) increased from C in both training groups with greater changes in ET than MT. Conclusions: In treated hypertensive men, aerobic training performed in the evening decreased clinic and ambulatory BP, due to reductions in SVR and vasomotor sympathetic modulation. Aerobic training conducted at both times of day increases baroreflex sensitivity, but with greater after ET.
The rheological behavior of alginate solutions were investigated for the optimal design of a biomanufacturing system to produce alginate structures for tissue engineering. Its rheological properties were determined by a rheometer through rotational and oscillatory tests. Experimental results were used to model the alginate solutions characteristics. The findings suggest that alginate solutions undergo shear-thinning effects with increasing shear rates. It is also possible to observe that its loss modulus is higher than the storage modulus ones being both modulus dependent upon the frequency, which is a typical characteristic of dilute solutions.
Three-dimensional (3D) cell culture has tremendous advantages to closely mimic the in vivo architecture and microenvironment of healthy tissue and organs, as well as of solid tumors. Spheroids are currently the most attractive 3D model to produce uniform reproducible cell structures as well as a potential basis for engineering large tissues and complex organs. In this review we discuss, from an engineering perspective, processes to obtain uniform 3D cell spheroids, comparing dynamic and static cultures and considering aspects such as mass transfer and shear stress. In addition, computational and mathematical modeling of complex cell spheroid systems are discussed. The non-cell-adhesive hydrogel-based method and dynamic cell culture in bioreactors are focused in detail and the myriad of developed spheroid characterization techniques is presented. The main bottlenecks and weaknesses are discussed, especially regarding the analysis of morphological parameters, cell quantification and viability, gene expression profiles, metabolic behavior and high-content analysis. Finally, a vast set of applications of spheroids as tools for in vitro study model systems is examined, including drug screening, tissue formation, pathologies development, tissue engineering and biofabrication, 3D bioprinting and microfluidics, together with their use in high-throughput platforms.
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