JBC, Vol. 253, Issue 13, 4697-4699, Jul, 1978
Permeation of the erythrocyte stroma by superoxide radical
R. E. Lynch and I. Fridovich
Superoxide anion, generated by xanthine oxidase within vesicles formed from
washed erythrocyte ghosts, crosses the vesicle membrane to reduce
cytochrome c in the medium (Lynch, R. E., and Fridovich, I. (1978) J. Biol.
Chem, 253, 1838-1845). To determine whether O2- could travel through the
membrane in the "channel" for the exchange of stable anions, the effects of
two specific inhibitors of anion exchange, 4-acetamido-4'-isothiocyano-2,2'
disulfonic acid stilbene (SITS) and 4,4'-diisothiocyano-2,2' disulfonic
acid stilbene (DIDS), on the escape of O2- from vesicles were studied. The
reduction of external cytochrome c, caused by O2- produced by the enzymic
turnover of internal xanthine oxidase, was 85 to 90% inhibited by SITS and
DIDS. If SITS impeded the egress of O2- from vesicles, it should enhance
the internal effects of O2- and antagonize the inhibition of these effects
by external superoxide dismutase. External superoxide dismutase inhibited
the lysis of vesicles containing xanthine oxidase. SITS (60 micron)
partially reversed this inhibition. It appears that O2- can cross the
membrane of the erythrocyte in the anion channel.
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