Effect of acidosis and anoxia on iron delocalization from brain homogenates.
Cortical homogenates were prepared from rat brain in Krebs-Ringer phosphate media adjusted to pH 7, 6 or 5 and incubated for 1 hr under aerotic or anaerobic conditions in the presence of dipyridyl, an iron chelator. Low molecular weight species (LMWS) iron was measured spectrophotometrically after passing of the homogenates through a 10,000-Mr ultrafiltration membrane. Following aerobic incubation, LMWS iron reached 1.24 micrograms/g tissue at pH 7, and increased 1.7-fold at pH 6 and 3.1-fold at pH 5. Anoxia enhanced significantly the amount of ultrafiltrable iron at the three pH values, the LMWS iron level being increased by 190% at pH 7, by 113% at pH 6, and by 77% at pH 5. Addition of the ultrafiltrates to brain membranes caused significant rises in the production of lipid peroxides assessed by the thiobarbituric acid test, indicating that LMWS iron was in a form capable for catalysing oxygen-derived free radical-mediated lipid peroxidation. It was concluded that decompartmentalization of intracellular iron may be an important factor in the initiation of peroxidative damage to ischemic cells.
Bralet
J
J
Laboratoire de Pharmacodynamie et Physiologie pharmaceutique, Faculté de Pharmacie, Université de Bourgogne, Dijon, France.
Schreiber
L
L
Bouvier
C
C
D015082:2,2'-Dipyridyl / Q000494:pharmacology; D000138:Acidosis / Q000378:metabolism; D000818:Animals; D001205:Ascorbic Acid / Q000494:pharmacology; D001923:Brain Chemistry; D005296:Ferrous Compounds / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D002534:Hypoxia, Brain / Q000378:metabolism; D007501:Iron / Q000378:metabolism* / Q000494:pharmacology; D015227:Lipid Peroxidation / Q000187:drug effects; D008054:Lipid Peroxides / Q000032:analysis; D008297:Male; D010100:Oxygen / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains
D005296:Ferrous Compounds; D008054:Lipid Peroxides; C020748:ferrous sulfate; D015082:2,2'-Dipyridyl; D007501:Iron; D001205:Ascorbic Acid; D010100:Oxygen