Abstract
Exercise is known to cause a vasodilatory response; however, the correlation between the vasorelaxant response and different training intensities has not been investigated. Therefore, this study evaluated the vascular reactivity and lipid peroxidation after different intensities of swimming exercise in rats. Male Wistar rats (aged 8 weeks; 250-300 g) underwent forced swimming for 1 h whilst tied to loads of 3, 4, 5, 6, and 8% of their body weight, respectively (groups G3, G4, G5, G6 and G8, respectively; n=5 each). Immediately after the test, the aorta was removed and suspended in an organ bath. Cumulative relaxation in response to acetylcholine (10−12-10−4 M) and contraction in response to phenylephrine (10−12-10−5 M) were measured. Oxidative stress was estimated by determining malondialdehyde concentration. The percentages of aorta relaxation were significantly higher in G3 (7.9±0.20), G4 (7.8±0.29), and G5 (7.9±0.21), compared to the control group (7.2±0.04), while relaxation in the G6 (7.4±0.25) and G8 (7.0±0.06) groups was similar to the control group. In contrast, the percentage of contraction was significantly higher in G6 (8.8 ±0.1) and G8 (9.7±0.29) compared to the control (7.1±0.1), G3 (7.3±0.2), G4 (7.2±0.1) and G5 (7.2±0.2%) groups. Lipid peroxidation levels in the aorta were similar to control levels in G3, G4 and G5, but higher in G6 and G8, and significantly higher in G8 (one-way ANOVA). These results indicate a reduction in vasorelaxing activity and an increase in contractile activity in rat aortas after high-intensity exercise, followed by an increase in lipid peroxidation.
Highlights
Improvements in vasomotor function are one of the many benefits associated with aerobic exercise
This postexercise response model is relevant to the development of post-exercise hypotension in humans, in which both hypertensive and normotensive subjects experience a reduction in blood pressure during the first minute after a single exercise session [10,11,12], which may continue for hours after the exercise session [13]
Aorta relaxation was significantly greater in G3, G4 and G5 compared to the control group (CG) (Figure 2A and B), as demonstrated by the values of pD2 (G3=7.9±0.20, G4=7.8±0.29, G5=7.9±0.21, CG=7.2±0.04, Po0.05)
Summary
Improvements in vasomotor function are one of the many benefits associated with aerobic exercise. Bechara et al [7] showed that improvements in the vasodilator response occurred immediately after a single exercise session performed on a treadmill at 60% of maximal exercise capacity, directly related to an increase in the bioavailability of endothelial nitric oxide and attenuation of the maximal contractile response [8,9] This postexercise response model is relevant to the development of post-exercise hypotension in humans, in which both hypertensive and normotensive subjects experience a reduction in blood pressure during the first minute after a single exercise session [10,11,12], which may continue for hours after the exercise session [13]. No studies have yet determined if vascular reactivity is involved in the differential blood pressure response to exercise intensity
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