Reciprocal protective effects of all-trans retinol and alpha-tocopherol during lipid peroxidation in retinal membranes.
Interactions between vitamin A and vitamin E in suppressing lipid peroxidation were observed in bovine retinal membrane preparations submitted to peroxidative injury by the water soluble azo initiator 2,2'-azobis(2-amidino-propane) hydrochloride (AAPH). Incorporation of 0.75 nmol mg prot(-1) all-trans retinol, an amount comparable with that of the endogenous alpha-tocopherol, significantly elongated the induction time preceding the release of TBA-reactive lipid peroxidation products, and reduced the consumption rate of the endogenous alpha-tocopherol. On the other hand, all-trans retinol was not able to induce any delay to the onset of lipid peroxidation when incorporated in membranes deprived of endogenous alpha-tocopherol by exposure to UV light, although TBARS produced within 60 min decreased slightly. Consumption of all-trans retinol during peroxidation was more rapid when all-trans retinol was incorporated in membranes deprived of alpha-tocopherol than in native membranes. These data suggest that reciprocal protective effects between vitamin A and vitamin E may strongly contribute to the defence of membranes against oxidative stress.
Tesoriere
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Istituto di Farmacologia e Farmacognosia e di Chimica Biologica, Università di Palermo, Italy.
Bongiorno
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A
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Livrea
M A
MA
D000578:Amidines / Q000494:pharmacology; D000818:Animals; D000975:Antioxidants / Q000493:pharmacokinetics / Q000494:pharmacology*; D002417:Cattle; D002462:Cell Membrane / Q000378:metabolism / Q000528:radiation effects; D002851:Chromatography, High Pressure Liquid; D007700:Kinetics; D015227:Lipid Peroxidation / Q000187:drug effects*; D012160:Retina / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D013997:Time Factors; D014466:Ultraviolet Rays; D014801:Vitamin A / Q000493:pharmacokinetics / Q000494:pharmacology*; D014810:Vitamin E / Q000378:metabolism / Q000493:pharmacokinetics / Q000494:pharmacology*
D000578:Amidines; D000975:Antioxidants; D014801:Vitamin A; D014810:Vitamin E; C046728:2,2'-azobis(2-amidinopropane)