CARMICHAEL, AJ , ARROYO GARCÍA, CARMEN MARTINA, COCKERHAM, LG
No
Free Radic. Biol. Med.
Article
Científica
01/01/1988
A1988M656300003
A possible mechanism by which disodium cromoglycate (DSCG) prevents a decrease in regional cerebral blood flow but not hypotension in primates following whole body gamma-irradiation was studied. Several studies have implicated superoxide radicals (O2-.) in intestinal and cerebral vascular disorders\'\' following ischemia and ionizing radiation, respectively. O2-. is formed during radiolysis in the reaction between hydrated elements (eaq-) and dissolved oxygen. For this reason, the efficiency of DSCG to scavenge eaq- and possibly prevent the formation of O2-. was studied. Hydrated electrons were produced by photolysis of potassium ferrocyanide solutions. The rate constant, k = 2.92 .times. 1010 M-1s-1 for the reaction between eaq- and DSCG was determined in competition experiments using the spin trap 5.5-dimethyl-1-pyrroline-N-oxide (DMPO). This spin trap reacts rapidly with eaq- followed protonation to yield the ESR observable DMPO-H spin adduct. The results show that DSCG is an efficient eqa- scavenger and may effectively compete with oxygen for eaq- preventing the radiolytic formation of O2-.