Effect of aging on permeability of cockerel aorta to 125I-albumin.

The in vivo uptake of 125I-albumin (A), containing < 1% free iodide, by the cockerel aorta 10-243 min after intravenous injection was quantitatively studied in 22 normotensive normolipemic anesthetized cockerels, Uptake initially was rapid and linear with time (T) (10-37 min), thereafter slowing and approaching an equilibrium with the blood. The permeability of the wall (Pm) to A was defined as accumulated wall activity/mean blood activity X endothelium surface area X T from intravenous injection to death of animal for T in the range 10-37 min. Pm was determined in the young group, age 197 +/- 51 days (means +/- SD; n = 6), which represented cockerels close to puberty, and compared to a middle-aged group, age 591 +/- 15 days (n = 5). Pm in the older group, 1.5 X 10(-6) +/- 0.218 ml . cm-2 . s-1 (means +/- 1 SE) was twofold greater than the younger group, 0.813 X 10(-6) +/- 0.046 (P < 0.0001). Total cholesterol content, within the wall in 12 different animals, was unchanged over the period 130-320 days. It is concluded that Pm to A increases with age as part of a physiological process. This finding should be considered in any model of atherosclerosis.