[The role of melanin in regulating free radical processes in the epithelial eye pigment in acute hypoxia].

Retinal response to the acute hypoxia and reoxygenation were shown to be independent of melanin presence in the eye pigmental epithelium (PE), i.e. in the retinas of both pigmented animals and albinos hypoxia survived an increase in the content of hydroperoxidases and malonyl dialdehyde; subsequent reoxygenation resulted in a more considerable accumulation of lipid peroxidation (LPO) products in both retinal types. Nevertheless under reoxygenation the number of malonyl dealdehyde became below the norm in PE of melanin-containing animals, but not in the albinos. At the same time acute hypoxia increased by 31% the electron spin resonance (ESR) uptake in the pigmented animals. Subsequent reoxygenation inconsiderably suppressed the intensity of the ESR signal. Under the above conditions pretreatment with Na2SeO3 increased the intensity of PE ESR uptake more than 2.5 times with following retrieval to the control level at the 20th minute of reoxygenation. We suggest that under hypoxia with subsequent reoxygenation the melano-protein granules favour regulation of LPO in PE, but not in other retinal layers, the findings being considerably different from those related to potent light effect.