Effect of essential phospholipids on the properties of ATPases of isolated rat liver plasma membranes of young and old animals.

"Essential" phospholipids (EPL), rich in dilinoleyl-phosphatidylcholine were given orally to young and 780-800 day-old rats. The double-labelled (14C/32P) dilinoleyl-phosphatidylcholine was incorporated in plasma membranes and the amounts incorporated into different organs investigated. Old animals incorporated higher radioactivity than young. The 14C/32P ratio however decreased in comparison with the substance administered. The amount of (Na+-K+)-ATPase in rat liver plasma membranes of old animals increased after pretreatment with EPL. The thermostability of ATPases was increased in plasma membranes of EPL treated old animals. In old animals EPL significantly lowered the cholesterol content. The membrane fluidity increased. The role of EPl in structural and functional properties of aged plasma membranes is discussed.