Lipid accretion in the perfused rabbit aorta

Abstract

A technique of in situ perfusion of rabbit abdominal aorta permitted measurement of rates of aortic lipid synthesis in conditions approaching the physiological. Aortic synthesis of fatty acids proceeded by both chain elongation and de novo pathways. Fatty acids synthesised in aorta from glucose were a quantitatively unimportant source of aortic lipid whereas perfusate free fatty acids were rapidly incorporated into aortic ester lipid. Aortic lipid glycerol was synthesised from labelled glucose and more than 96 % of the label in aortic lipid was in non-fatty acid moieties. While tri- and diglycerides were synthesised in aorta from perfusate glucose and free fatty acids, aortic phospholipids were the major ester-product (> 56 %) of these substrates. Phosphatidylcholine was the major phospholipid synthesised and was formed by de novo synthesis although data was also compatible with the presence of a lysophosphatide pathway in intima. Phosphatidylinositol was rapidly synthesised and glucose carbon entered glycerol but not inositol of this lipid.

The possibility of contamination of aortic lipid with radioactive lipid from periaortic adipose tissue was emphasised by the demonstration that rates of lipid synthesis from various substrates were 30–400 times greater in periaortic adipose tissue than in aorta.