[Age-related characteristics of the metabolism of fatty acid components of nuclear phospholipids]. / Vozrastnye osobennosti obmena zhirnokislotnykh komponentov iadernykh fosfolipidov.

The metabolism of liver nuclear phospholipid acyl components of rats of various age was studied in vitro. It was found that the activity of phospholipases A1 and A2 in the nuclei sharply increased in animals aged 1-3 months, showing a decrease in 12- and 24-month-old animals. The incorporation of labeled arachidonic acid into nuclear phospholipids remained practically unchanged thereby. The age-specific fluctuations in the activity of nuclear phospholipids A1 and A2 may be one of possible reasons of changes in the fatty acid composition of nuclear lipids during ontogenesis.

[Structural state of rat liver mitochondrial and microsomal membranes in aging and after treatment with thyroxine]. / Strukturnoe sostoianie membran mitokhondrii i mikrosom pecheni krys pri starenii i pod deistviem tiroksina.

Rotation mobility of stearic acid spin labelling in mitochondria and microsomes of 24 months old rats is shown to decrease in comparison with that of 1 month rats. This decrease correlates with an increase in the free cholesterol content in membranes. The phospholipid composition is practically unchanged. With age the osmoresistance of organelles decreases and the cryoresistance increases, supporting indirectly the existence of structural changes in membranes with ageing. The most pronounced activation of NADPH-cytochrome C reductase in the microsomal membrane after the treatment with triton X-100 is observed in case of old animals. The thyroxine treatment of old rats causes a "rejuvenative" effect on the structural state of mitochondrial and microsomal membranes, evidencing for the important role of hormonal regulation in mechanisms of their age rearrangement.