AGE-RELATED VARIATIONS IN TRANSPORT-PROPERTIES OF THE RABBIT ARTERIAL-WALL NEAR BRANCHES

Lipid accumulation in the human aorta occurs predominantly downstream of branches in foetuses, neonates and infants but upstream at later ag es. The lipid in these deposits may derive from plasma lipoproteins. W e have examined uptake of plasma proteins by the rabbit aortic wall ne ar branches as a function of age. Albumin was labelled with a fluoresc ent dye and introduced into the circulation of animals fed a normal di et. The aorta was fixed in situ 3 h later and the distribution of trac er in sections through the wall was measured by using digital imaging fluorescence microscopy. Net uptake by the intima-media was higher dow nstream of intercostal ostia than upstream in young animals but this d ifference decreased and then reversed with age. Furthermore, the avera ge of uptake by both regions was higher shortly after weaning than at later ages. These age-related variations in transport properties may e xplain discrepancies between previous studies of uptake, resolve appar ent inconsistencies between the properties of rabbit and human arterie s and, if applicable to man, might account for the non-uniform and cha nging pattern of lipid accumulation around arterial branches.