Repetitions of Strenuous Exercise Consistently Increase Paraoxonase 1 Concentration and Activity in Plasma of Average‐Trained Men

Abstract

Objectives. Oxidative stress, induced by physical activity, may stimulate the expression, release, and activity of certain antioxidant enzymes. We investigated the effect of three repeated bouts of strenuous exercise on paraoxonase 1 concentration (PON1c) and paraoxonase activity (PON). Methods. Eleven average-trained healthy men (age 34.0 ± 5.2 years) performed three strenuous exercise tests on a treadmill separated by 72 hours periods of resting. PON1c, PON, ferric-reducing activity of plasma (FRAP), lipid profile, C-reactive protein concentration (CRP), and lactate concentration were determined in plasma. Results. Each exercise bout resulted in similar PON1c, PON, FRAP, and high-density lipoprotein concentration (HDL-C) increments, while PON/HDL-C ratio remained stable in all repetitions. Percentage increments at the bout of each exercise were higher for PON1c (by 64.82% at the first, by 92.9% at the second, and by 77.02% at the third exercise) than for PON (by 6.49% at the first, 10.06% at the second, and by 12.32% at the third exercise). Association was found between preexercise PON and PON1c ( r = 0.56 , p = 0.029 ), pre- ( r = 0.87 , p = 0.00003 ) and postexercise HDL-C ( r = 0.6 , p = 0.0002 ), preexercise PON and cardiovascular fitness level of participants measured as VO2max ( r = 0.39 , p = 0.026 ), and postexercise PON and lactate concentration ( r = 0.44 , p = 0.01 ). Conclusions. PON1c and PON increase during strenuous exercise, yet the effect of exercise on PON1 concentration is more pronounced. PON1 does not show tolerance to physical activity. The enzyme may provide short-term protection from oxidative stress in each exercise bout. PON may depend on exercise load. Cardiovascular fitness levels may be associated with PON1 activity.

Effect of Exercise Repetitions on Arylesterase Activity of PON1 in Plasma of Average-Trained Men—The Dissociation between Activity and Concentration

“…The plasma was stored at −80 °C for further analysis. Details of the study design have been presented earlier [ 23 , 35 ].…”

“…The measurement of other biochemical determinations in plasma used for correlation analysis was as described in the previous study [ 23 ]. Briefly, PON1 concentration (PON1c) was assessed using an ELISA Kit for paraoxonase 1 (USCN Life Sciences, Inc., Wuhan, China); FRAP was measured spectrophotometrically by a method described by Benzie and Strain [ 37 ].…”

“…Our previous research shows that strenuous exercise results in a significant increase in PON activity and PON1 concentration in the plasma of young men, which contributes to the observed increase in the ferric-reducing activity of plasma (FRAP) [ 19 , 21 , 22 , 23 ]. This increase in PON activity is followed by a decrease, or at least a return to baseline levels, an hour and two hours after exercise.…”

“…In a previous study, we noticed that increments in PON activity were hampered by prolonged exercise [ 23 ]. The causative mechanisms of this activity inhibition may be associated with a fall in pH during strenuous exercise to a level that is below the optimal pH for PON1 activity.…”

Effect of Carotenoids on Paraoxonase-1 Activity and Gene Expression

“…This implies that some mechanisms evoked by physical activity stimulate PON1. Free radicals released during physical exercise may upregulate antioxidant enzyme expression [ 72 ].…”