Effect of asphyxia on the composition of cationic elements in the perilymph.

To elucidate the role of free radicals in the cochlea, cationic elements in the perilymph of the scala tympani in normal and asphyxic guinea pigs were measured by an inductively coupled plasma atomic emission spectrometer. The concentrations of 7 cationic elements (i.e., calcium, copper, iron, magnesium, phosphorus, lead and zinc) were measured simultaneously in a sample of the perilymph taken before, during and after asphyxia. There was no significant change in these cationic elements during asphyxia for 3 min. In contrast to the stationary level during asphyxia, the iron concentration was significantly elevated at 5 min after re-ventilation following asphyxia and decreased rapidly toward the pre-asphyxic level thereafter, although no significant change was observed in other cationic elements. These results were comparable to the theory of non-protein-bound iron accumulation produced by an O2-dependent mechanism during re-perfusion.