In Vitro Phospholipid Synthesis in Normal and Atheromatous Rabbit Aortas

Abstract

The incorporation of P 32 -phosphate and C 14 -choline into normal and atherosclerotic rabbit aortas was studied extensively in vitro . The same results as observed in vivo were found, namely an enhanced synthesis of phospholipids by the atheromatous aorta, localized primarily in the intima. Aortic intimal phospholipids incorporated more choline than phosphate. Tests with cyanide and fluoride showed that the higher incorporation of choline could not be attributed to exchange with preformed aortic phospholipid but presumably was due to differences in intermediate metabolic pools. The difference in distribution of P 32 between the two most active phospholipid classes, phosphatidyl choline and phosphatidyl inositol, of normal and atherosclerotic aortas was similar in vivo and in vitro . In the normal aorta, phosphatidyl inositol had a higher percentage of P 32 than phosphatidyl choline; in the atheromatous aorta, these percentages were reversed. The studies in vitro were used as evidence to show that the enhanced synthesis observed in vivo was probably not mediated by neural factors or stretch of the aorta, and that synthesis in situ could account for the higher amounts of phospholipid present in the atheromatous aorta.