RESUMO
Initial experiments were conducted using an in situ rat tibialis anterior (TA) muscle preparation to assess the influence of dietary antioxidants on muscle contractile properties. Adult Sprague-Dawley rats were divided into two dietary groups: 1) control diet (Con) and 2) supplemented with vitamin E (VE) and alpha-lipoic acid (alpha-LA) (Antiox). Antiox rats were fed the Con rats' diet (AIN-93M) with an additional 10,000 IU VE/kg diet and 1.65 g/kg alpha-LA. After an 8-wk feeding period, no differences existed (P > 0.05) between the two dietary groups in maximum specific tension before or after a fatigue protocol or in force production during the fatigue protocol. However, in unfatigued muscle, maximal twitch tension and tetanic force production at stimulation frequencies < or = 40 Hz were less (P < 0.05) in Antiox animals compared with Con. To investigate which antioxidant was responsible for the depressed force production, a second experiment was conducted using an in vitro rat diaphragm preparation. Varying concentrations of VE and dihydrolipoic acid, the reduced form of alpha-LA, were added either individually or in combination to baths containing diaphragm muscle strips. The results from these experiments indicate that high levels of VE depress skeletal muscle force production at low stimulation frequencies.
Assuntos
Antioxidantes/farmacologia , Músculo Esquelético/efeitos dos fármacos , Ácido Tióctico/farmacologia , Vitamina E/farmacologia , Animais , Antioxidantes/metabolismo , Diafragma/efeitos dos fármacos , Diafragma/fisiologia , Dieta , Estimulação Elétrica , Feminino , Peroxidação de Lipídeos/efeitos dos fármacos , Contração Muscular/efeitos dos fármacos , Fadiga Muscular/efeitos dos fármacos , Músculo Esquelético/metabolismo , Ratos , Ratos Sprague-Dawley , Substâncias Reativas com Ácido Tiobarbitúrico/metabolismo , Ácido Tióctico/metabolismo , Vitamina E/metabolismoRESUMO
Analyses were made of chlorophyll a and b and fatty acids (18:3, 18:2, 18:1, 18:0, 16:2, 16:1, and 16:0) of greening and senescing leaf tissue. Those dark-grown tissues given a prior treatment of red, far red, or red followed by far red light showed similar increases in chlorophylls and linolenate (18:3) when exposed to continuous white light. In contrast, green barley (Hordeum vulgare L.) leaves placed in the dark lost chlorophylls and fatty acids, especially 18:3. Senescing cocklebur (Xanthium strumarium L.) leaf tissue showed a decline in chlorophyll and fatty acids, especially again 18:3. Abscisic acid, but not sucrose, accelerated these senescent changes. Radioactive acetate incorporation into the galacto-lipids and phospholipids of senescing cocklebur leaf tissue increased and then the radioactivity of the lipids decreased in senescent tissues.
