BACKGROUND: As assessed by flow cytometry, the increase in hydrogen peroxide in individual neutrophils from old volunteers was significantly greater than in neutrophils from young volunteers. To explain the discrepancy in previous reports that showed reduced superoxide generation with age and our finding, we measured the kinetics of antioxidative enzymes. METHODS: Neutrophils were obtained from young (ages 21-34) and old (ages over 65) volunteers. The increase in hydrogen peroxide following stimulation with formyl peptide in individual neutrophils was assessed by flow cytometry by using dihydrorhodamine 123. The enzyme kinetics was determined from the best fit curve using Michaelis-Menten equations. RESULTS: Aging was associated with a significant reduction in the Vmax for glutathione peroxidase. The decreased activity was not due to selenium deficiency as the serum and neutrophil concentrations were identical with age. Following activation, a significant increase in the Km was noted in neutrophils from young but not from old volunteers. CONCLUSIONS: These results account for the increased intracellular accumulation of hydrogen peroxide as a function of age in stimulated neutrophils. These results provide evidence in humans of an age-related impairment in antioxidative defense mechanisms that support the free radical theory of aging.
BACKGROUND: As assessed by flow cytometry, the increase in hydrogen peroxide in individual neutrophils from old volunteers was significantly greater than in neutrophils from young volunteers. To explain the discrepancy in previous reports that showed reduced superoxide generation with age and our finding, we measured the kinetics of antioxidative enzymes. METHODS: Neutrophils were obtained from young (ages 21-34) and old (ages over 65) volunteers. The increase in hydrogen peroxide following stimulation with formyl peptide in individual neutrophils was assessed by flow cytometry by using dihydrorhodamine 123. The enzyme kinetics was determined from the best fit curve using Michaelis-Menten equations. RESULTS: Aging was associated with a significant reduction in the Vmax for glutathione peroxidase. The decreased activity was not due to selenium deficiency as the serum and neutrophil concentrations were identical with age. Following activation, a significant increase in the Km was noted in neutrophils from young but not from old volunteers. CONCLUSIONS: These results account for the increased intracellular accumulation of hydrogen peroxide as a function of age in stimulated neutrophils. These results provide evidence in humans of an age-related impairment in antioxidative defense mechanisms that support the free radical theory of aging.
Authors: S A Hernández-Escobar; M C Avila-Casado; V Soto-Abraham; O L López Escudero; M E Soto; M L Vega-Bravo; T Fortoul van der Goes; Elba Reyes-Maldonado Journal: Int Arch Occup Environ Health Date: 2008-11-26 Impact factor: 3.015
Authors: Cheng Zhang; Ching-Chang Kuo; Setareh H Moghadam; Louise Monte; Kenner C Rice; Robert A Rissman Journal: J Alzheimers Dis Date: 2015 Impact factor: 4.472
Authors: Sara E Espinoza; Hongfei Guo; Neal Fedarko; Amy DeZern; Linda P Fried; Qian-Li Xue; Sean Leng; Brock Beamer; Jeremy D Walston Journal: J Gerontol A Biol Sci Med Sci Date: 2008-05 Impact factor: 6.053