Neutrophil Tolerance to Oxidative Stress Induced by Hypoxia/Reoxygenation

Abstract

Repetitive episodes of hypoxia/reoxygenation induce cellular adaptations resulting in a tolerance process against oxidative stress. We studied the effects of chronic episodes of hypoxia/reoxygenation on neutrophil antioxidant defenses, neutrophil oxidative capability, and oxidative damage induced in neutrophils and plasma. Seven professional apnea divers participated in the study. Blood samples were taken under basal conditions, after a diving apnea session, and under basal conditions after five consecutive days of diving apnea sessions (basal post-diving). Chronic episodes of hypoxia/reoxygenation increased malondialdehyde (MDA), carbonyl derivates and creatine kinase (CPK) in plasma. Neutrophil catalase (CAT) levels were higher in basal post-diving. Neutrophil oxidative burst was maintained after diving, although the maximum response was delayed in basal post-diving. Neutrophil thioredoxin reductase (TR) activity increased in basal post-diving, and glutathione reductase (GR) activity was maintained. Chronic, repetitive episodes of diving apnea induce neutrophil adaptations in order to delay the oxidative burst response and to facilitate protein reduction. Diving apnea could be a good model to study tolerance to the oxidative stress generated by hypoxia/ reoxygenation.

Vitamin C supplementation influences the antioxidant response and nitric oxide handling of erythrocytes and lymphocytes to diving apnea

“…Diving apnea increases circulating neutrophils and plasma CK levels suggesting the presence of an APIR similar to that which takes place after exercise, after ischemia/reperfusion or after infection (Shek and Shephard, 1998;Tauler et al, 2003;Sureda et al, 2004a). The low values of maximal heart rate and the mean heart rate measured in divers during a diving apnea session indicate exercise of a moderate intensity, even taking into account the bradycardia induced by apnea.…”

“…Exercise increases tissue oxygen demand, but a limited amount of oxygen is available in diving apnea, thus inducing tissue hypoxia. We evidenced that diving apnea induces oxidative stress and initiates neutrophil reactions resembling the acute phase immune response (APIR) (Sureda et al, 2004a). We also evidenced that chronic and repetitive episodes of diving apnea induce neutrophil adaptations in order to delay the oxidative burst response and enhance antioxidant levels (Sureda et al, 2004b).…”

“…We evidenced that diving apnea induces oxidative stress and initiates neutrophil reactions resembling the acute phase immune response (APIR) (Sureda et al, 2004a). We also evidenced that chronic and repetitive episodes of diving apnea induce neutrophil adaptations in order to delay the oxidative burst response and enhance antioxidant levels (Sureda et al, 2004b). Several data show that antioxidant enzymes and low-molecular-weight reactive oxygen species (ROS) scavengers inhibit reoxygenation injury in cellular models (Horakova et al, 1997;Colantoni et al, 1998;Isowa et al, 2000).…”

“…The repetitive episodes of hypoxia-reoxygenation associated to diving apnea could increase ROS production, inducing oxidative stress and altering the NO availability by cells (Elsner et al, 1998;Sureda et al, 2004a). The effects of the diet supplementation with vitamin C in the erythrocyte capability to generate NO after hypoxia-reoxygenation could contribute to explain the vasodilatador effects of ascorbate.…”

“…The study protocol was in accordance with the Declaration of Helsinki and was approved by the local ethics committee (Ethical Committee of 'Hospital Universitari Son Dureta'). Dietary intake of energy, macronutrients, minerals and vitamins of each participant were assessed using a 7-day 24-h recall before the day of the study (Sureda et al, 2004a). This study was a double blind crossover study.…”