AGE-RELATED-CHANGES IN LIPID SECRETION OF PERFUSED LIVERS FROM MALE WISTAR RATS DONORS

Male Wistar rats show typical age-related variations in the distributi on of high-density lipoprotein subfractions that include an increase i n HDL1 and a decrease in HDL2 proportion. The role of liver in these v ariations was evaluated by studying the lipoprotein and bile secretion s from perfused livers of 14+/-1 and 3.5+/-0.5 month old Wister rats ( adult and young animals, respectively). The lipid content of lipoprote ins secreted from adult livers was higher in HDL2 fraction and lower i n VLDL fraction. The lipid output did not show significant age-related variations in the case of HDL1 fraction. However, the lipoproteins se creted from adult livers contained a higher proportion of phospholipid s, and a lower proportion of triacylglycerols in comparison with lipop roteins secreted by young livers. Therefore, the molar ratio of core t o surface lipids was lower in lipoproteins secreted by adult livers. A dult livers showed a reduction in bile how by about 37% with a signifi cantly higher phospholipid secretion. These findings suggest that both the hepatic metabolism of glycerophospholipids and their repartition between plasma and bile compartments are affected by aging process. In conclusion, present data show that the age-related increase in plasma HDL1 proportion, previously observed in this rat strain in vivo, are not due to a higher liver secretion of these particles. Conversely, li ver appears to have a major role in the age-related VLDL increase and in the variations of phospholipid lipoprotein secretion.