Nr. Aiken et al., A PEROXIDATIVE MODEL OF HUMAN ERYTHROCYTE INTRACELLULAR CA2-VIVO CELLAGING - MEASUREMENT BY F-19-NMR SPECTROSCOPY( CHANGES WITH IN), Biochimica et biophysica acta. Molecular basis of disease, 1270(1), 1995, pp. 52-57
Numerous changes occur with human erythrocyte aging in vivo, including
an increase in free ionic intracellular calcium concentration ([Ca2+]
(i)) (N.R. Aiken et al. (1992) Biochim. Biophys. Acta 1136, 155-160).
An attractive hypothesis of cell aging suggests that oxidative stress
is responsible for many age-related changes. To determine whether oxid
ative stress leads to increased intracellular Ca2+ concentrations, we
used the fluorinated calcium probe 5,5'-difluoroBAPTA and fluorine nuc
lear magnetic resonance spectroscopy (F-19-NMR) to measure [Ca2+](i) f
ollowing mild hydrogen peroxide (H2O2) stress to young red cells. Cell
s were separated using density centrifugation, exposed to 815 mu M H2O
2, loaded with the calcium probe, and [Ca2+](i) measured. Intracellula
r [Ca2+] increased from 62 nM (+/-4, S.E.) in untreated young cells to
173 nM (+/-11)in peroxide treated cohort young cells. This value appr
oached our previously reported [Ca2+](i) of 221 nM (+/-25) in old huma
n erythrocytes. Pretreatment of young cells with (a) cobalt, which blo
cks Ca2+ influx through calcium channels, or (b) carbon monoxide, whic
h prevents methemoglobin formation, inhibited the peroxide-induced inc
rease in ionic intracellular calcium. These findings are consistent wi
th the hypothesis that oxidative stress of erythrocytes contributes to
the increased [Ca2+](i) found in senescent cells, and that this is du
e to increased membrane Ca2+ leak resulting from oxidatively induced m
ethemoglobin-cytoskeletal protein crosslinking.