Basic mechanisms underlying the production of photochemical lesions in the mammalian retina
| Autor: | J E Millen, J J Ruffolo, Harold A. Mueller, W.T. Ham, Guerry D rd, Cleary Sf, R.K. Guerry |
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| Rok vydání: | 1984 |
| Předmět: |
Free Radicals
Light Photochemistry chemistry.chemical_element Oxygen Methylprednisolone Retina Lesion Cellular and Molecular Neuroscience medicine Animals biology Chemistry Oxygenation beta Carotene Carotenoids Sensory Systems Ophthalmology medicine.anatomical_structure Catalase biology.protein Arterial blood Macaca medicine.symptom Phototoxicity medicine.drug |
| Zdroj: | Current eye research. 3(1) |
| ISSN: | 0271-3683 |
| Popis: | Extended exposure (100s) of the macaque retina to blue light (400-500nm) produces a photochemical type or types of lesion. The basic mechanisms responsible for such photic damage are unknown but the toxic combination of light and oxygen leading to the free radicals O-.2, H2O2, OH., and O2(1 delta) have been suggested as a possible source of the phototoxicity. To test this hypothesis, the radiant exposure (J. cm-2) to short wavelength light (435-445nm) required for minimal damage in the macaque retina is under investigation as a function of oxygenation and after administration of substances known to either inhibit/scavenge radicals or act as anti-inflammatory/anti-oxidant agents. Substances under study include beta-carotene, steroids, catalase and SOD. Here we report radiant exposure in J.cm-2 needed to produce a minimal lesion vs oxygenation as measured by partial pressure of O2 in arterial blood (Po2). There is a sharp drop in the radiant exposure threshold with increase in the partial pressure of O2 in arterial blood, e.g. 30 J.cm-2 at 75 torr to 10 J.cm-2 at 271 torr, a factor of 3. Methylprednisolone injected intravenously one hour before exposure (125 mg) has been shown to raise the threshold for retinal damage in two macaques by a factor of approximately 2. Another animal fed beta-carotene (7.5 mg daily) over a period of 3 months has been exposed to blue light at several levels of oxygenation. The results suggest a protective effect. |
| Databáze: | OpenAIRE |
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