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    Influence of membrane fluidity on 5'-nucleotidase activity in isolated hepatocyte plasma membrane

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    The influence of membrane microviscosity on 5'-nucleotidase activity has been investigated on liver plasma membrane preparations from rats during aging and following diet restriction. In addition the microviscosity of membranes from old rats was changed in vitro by the Active Lipids. During aging the membrane microviscosity increased progressively and in parallel the activity of 5'-nucleotidase decreased. Diet restriction was able to slow down the modification of both parameters. The experiment performed with the Active Lipids further supports that membrane microviscosity modulated the enzyme activity

    Food restriction in female Wistar rats. II. β-adrenoceptor density in the cerebellum and in the splenic lymphocytes

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    The effect of diet restriction, applied on an every-other-day schedule from 3.5 months of age on, has been investigated on the β-adrenoceptor density in the cerebellum and in the splenic lymphocytes of old female Wistar rats. Comparing animals 6 months and 24 months old fed ad libitum, a 75% age-dependent reduction in specific binding of the agonist dihydroalprenolol was observed in cerebellar membrane preparations, while the β-adrenoceptor density of lymphocytes remained unaltered. Diet restriction induced a partial recovery of the age-related decrease of this parameter in the cerebellum without affecting the receptor density of lymphocytes. Present results suggest that undernutrition delays the appearance of those alterations related to aging. © 1990
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