Aorta elastin turnover in normal and hypercholesterolemic Japanese quail.

The turnover and degradation of mature elastin from the aortae of Japanese quail were estimated following injection with L-[U-14C]lysine by measuring the changes in specific activity of L-[U-14C]lysine and 14C-labelled desmosine and isodesmosine (crosslinking amino acids derived from lysyl residues) in elastin over a 39-week period. Only 5% of the variation in radioactivity could be attributed to changes in time. Therefore, it was concluded that the best estimates of mature elastin turnover are only quantifiable in years. Dietary cholesterol in amounts sufficient to induce plaque formatioin and fragmentation of the elastic lamina in the aorta did not significantly influence turnover time. It would appear that once the total pool of elastin in aorta is stabilized as mature fibers it is not subject to proteolysis or resynthesis of sufficient magnitude to result in measurable turnover.