Changes in Pro-and Anti-Oxidants and Vascular Reactivity Before and After Acute Exercise

Abstract

An acute bout of exercise has been shown to increase oxidative stress markers, which if not immediately buffered may contribute to microvascular and muscular damage. Knowledge about the balance between pro and anti-oxidants during and immediately following an acute bout of exercise may provide insight into the magnitude and length of exposure of the vasculature to oxidative stress. PURPOSE: This study examined the effects of an acute bout of exercise on the balance of markers of pro and anti-oxidants and vascular reactivity at rest, peak exercise, and 20-minutes post exercise. METHODS: : Nine well-trained athletes (Age 33.3 ±7.3 years; Height 73.38 ± 2.72 inches; Weight 188.75 ± 17.32 lbs) participated in a 30 minute bicycle time-trial (@ 85% HRR). Venous blood samples and brachial artery diameters and reactivity were obtained at three time points: 1) before exercise, 2) at peak exercise, and 3) 20 minutes after exercise. Plasma samples were analyzed for peroxynitrite by EPR spectroscopy and for glutathione peroxidase by enzymatic assay. Brachial artery diameters and reactivity were examined before and after 5 min of forearm occlusion at each time point. RESULTS: Average heart rate and VO2 during exercise were 160±12 bpm and 38.51±6 ml/kg/min, respectively. Peroxynitrite and brachial artery diameters increased significantly from rest to peak exercise and returned to baseline levels at 20 minutes (Peroxynitrite: Pre: 0.246, Peak: 0.336, Post: 0.228 U/min, p<0.05; Brachial Artery Diameter: Pre: 5.00±0.42, Peak: 5.26±0.24, Post: 4.88±0.40mm, p<0.05), while glutathione peroxidase and brachial reactivity decreased from rest to peak exercise and returned to near baseline levels after 20 minutes of rest (Glutathione Peroxidase Pre: 88.76, Peak: 64.66, Post: 89.47 nmols/mg protein /min, p<0.05; Brachial Reactivity: Pre: 3.27±4.72, Peak:−0.40±1.26, Post: 2.92±1.86%, p<0.05). CONCLUSIONS: Our findings indicate that intense exercise results in significant formation of peroxynitrite, probably secondary to a rise in super oxide and nitric oxide, and that this transient rise is in part buffered by anti-oxidant defense systems during exercise and are resolved within 20 minutes of recovery. In addition, intense exercise results in a transient increase in brachial artery dimensions and decrease in brachial reactivity.