Hypobaric hypoxia-reoxygenation diminishes band 3 protein functions in human erythrocytes

Abstract

We have previously shown that subjects exposed to acute hypobaric hypoxia display an erythrocyte membrane protein band 3 with an increased susceptibility to proteolytic degradation. We suggested it was due to an oxidative damage of band 3. We now report that exposure to hypobaric hypoxia followed by reoxygenation affects protein band 3 functions such as anion transport and binding of glyceraldehyde-3P-dehydrogenase. Transport capacity was assessed with the fluorescent probe 2-[N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino] ethanesulfonate (NBD-taurine). Binding capacity was evaluated from the activity of the membrane-associated enzyme. Healthy young men were exposed for 20 min to hypobaric hypoxia, simulating an altitude of 4,500 m above sea level and after recompression band 3 function was assessed. An inhibition of band 3 anion transport function and a decrease in the binding of glyceraldehyde-3P-dehydrogenase to band 3 were observed. Evidence is given supporting the hypothesis that functional alteration of band 3 is due to its oxidative modification originated as a consequence of the exposure to hypobaric hypoxia and further reoxygenation.

Lung oxidative stress as related to exercise and altitude. Lipid peroxidation evidence in exhaled breath condensate: a possible predictor of acute mountain sickness

“…Therefore, hypoxia seems to induce OS in lung (Wood et al 2000;Hoshikawa et al 2001;Minko et al 2002). Hypobaric hypoxia induced alterations of cell membrane structure and function appears to be mediated by OS (Celedo´n et al 1998;Behn et al 1999;Gonza´lez et al 2002). OS, therefore, may be involved in high-altitude-related pathology, like acute mountain sickness (Wood et al 2000;.…”

Intermittent hypobaric hypoxia‐induced oxidative stress in rat erythrocytes: protective effects of vitamin E, vitamin C, and carnitine

“…7 Under hypoxic conditions, autooxidation of hemoglobin (Hb) is facilitated by an increased flux of superoxide radicals 8 and damage to membrane proteins may result from association of superoxide with Hb at reduced oxygen pressure. 6,9 In our earlier studies on rat erythrocytes, we have demonstrated that there is an increase in protein oxidation on exposure to intermittent hypobarichypoxia in trained rats and that the extent of increase in carbonyl content was greater at 6300 m than at 5700 m when compared to sedentary controls. 10 The present study was aimed at understanding the effect of intermittent hypobaric hypoxia (IHH) and antioxidants in ameliorating OS in erythrocytes of rats.…”

“…An extinction coefficient of 43. 6 Mcm À1 was used to determine enzyme activity. One unit is equivalent to 1.0 mole of H 2 O 2 degraded/min/mg Hb.…”

“…Hb readily associates with the erythrocyte membrane at reduced oxygen pressure 31,32 and the generated ROS overcome the cytoplasmic antioxidant defence and damage the membrane proteins. 6 In an earlier study, we demonstrated that IHH involving hypoxia followed by reoxygenation results in an increased protein oxidation at an altitude of 6300 m. 10 Vitamins E and C, are reported to quench free radicals as long as cellular reducing power is available. 33 Thus, they can act synergistically when the initiating radicals are generated within the lipid core of the membrane.…”

Hypoxia-Induced Post-Translational Changes in Red Blood Cell Protein Map of Newborns

“…Other authors have observed that deoxygenation increases the degree of Tyr phosphorylation of band 3 in RBC (31) with an increase in glycolytic enzyme activities (11). Gonzalez et al (32) observed that exposure to hypobaric hypoxia followed by reoxygenation induced inhibition of band 3 anion transport function and a decrease in binding of G3PDH to band 3. In the present study, we observed increased G3PDH Tyr-phosphorylation in neonatal RBC samples after 16 h of hypoxic incubation as well as after 8 h of reoxygenation with respect to starting level at time 0.…”