title: Circadian variations in antioxidant defences and lipid peroxidation in the rat heart.
abstract: Circadian variations in antioxidant defences and lipid peroxidation were investigated in 12 rat hearts perfused during light (i.e., at 08.00, n = 6) and dark cycle (i.e., at 19.00, n = 6). Higher levels of non proteic thiol compounds (P < 0.01), glutathione transferase activity (P < 0.05) and lipid peroxidation (P < 0.01) were detected in evening-excised hearts, associated with a lower (P < 0.05) selenium-dependent glutathione peroxidase activity; superoxide dismutase and glutathione reductase activities, as well as vitamin E content, were similar in the two groups. Moreover, a greater release of thiobarbituric acid reactive substances (P < 0.01) and proteins (P < 0.05) was detected in the myocardial effluent of another group of 5 evening-excised hearts perfused with Krebs-Henseleit buffer containing 30 microM cumene hydroperoxide, as compared to 5 light-cycle hearts. In conclusion, a higher oxidative stress seems to be operative in the rat heart during early stages of the dark phase, in spite of the increase level of non proteic thiol compounds (namely, glutathione). An imbalance of antioxidant defences, and/or higher radical generation and unsaturation degree of biomembranes lipids, may be hypothesized to favour myocardial oxidative stress at the beginning of the motor activity phase in rats.
authors.affiliation: Cattedra di Patologia Speciale Medica, Università G. D'Annunzio, Facoltà di Medicina e Chirurgia, Chieti, Italy.
authors.forename: D
authors.initials: D
authors.lastname: Lapenna
authors.forename: S
authors.initials: S
authors.lastname: De Gioia
authors.forename: A
authors.initials: A
authors.lastname: Mezzetti
authors.forename: E
authors.initials: E
authors.lastname: Porreca
authors.forename: G
authors.initials: G
authors.lastname: Ciofani
authors.forename: L
authors.initials: L
authors.lastname: Marzio
authors.forename: F
authors.initials: F
authors.lastname: Capani
authors.forename: C
authors.initials: C
authors.lastname: Di Ilio
authors.forename: F
authors.initials: F
authors.lastname: Cuccurullo
mesh_terms: D000818:Animals; D001555:Benzene Derivatives; D002940:Circadian Rhythm / Q000502:physiology*; D006439:Hemodynamics / Q000187:drug effects; D015227:Lipid Peroxidation / Q000502:physiology*; D008297:Male; D009206:Myocardium / Q000378:metabolism*; D010084:Oxidation-Reduction; D010477:Perfusion; D011506:Proteins / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D017392:Thiobarbituric Acid Reactive Substances / Q000378:metabolism
chemical_list: D001555:Benzene Derivatives; D011506:Proteins; D017392:Thiobarbituric Acid Reactive Substances; C007164:cumene hydroperoxide