Pj. Stone et al., DISTRIBUTION OF ELASTIN IN HAMSTERS AND THE TURNOVER RATES OF DIFFERENT ELASTIN POOLS, Proceedings of the Society for Experimental Biology and Medicine, 215(1), 1997, pp. 94-101
Desmosine (DES) and isodesmosine (IDES) concentration in the urine can
be used as a noninvasive method of assessing degradation of mature el
astin in normal and pathologic states, The present study was undertake
n to determine the distribution of elastin among organs and tissues of
normal hamsters, and to determine the turnover rates of two elastin-c
ontaining organs (lung, thoracic aorta) as a reflection of their contr
ibutions to DES and IDES excretion in the urine, Hamsters were metabol
ically labeled at 5 days of age with C-14-lysine and studied at 1.5, 4
.5, 8, and 12 months of age. The aorta DES+IDES-associated radioactivi
ty did not change significantly over the age span of 1.5-12 months, Lu
ng DES+IDES-associated radioactivity decreased with a half-life of 420
days. Measurement of DES+IDES pools in other tissues, with relatively
low concentrations of elastin, was carried out by the isotope dilutio
n technique, At 12 months of age, the head and paws pool, skin, skelet
al muscle, gastrointestinal tract, heart-liver-kidney-spleen pool, lun
gs, and thoracic aorta represented 37%, 28%, 13%, 11%, 6%, 4%, and 1%,
respectively, of total body DES+IDES. The organs with the highest DES
+IDES-specific radioactivity at 12 months were heart-liver-kidney-sple
en, lung, and gastrointestinal tract, with 310, 217, and 217 dpm/nmol,
respectively, Skin had the lowest specific radioactivity, with 90 dpm
/nmol. The specific radioactivity of DES+IDES in urine was 62 dpm/nmol
at 12 months, down from 251 dpm/nmol at 1.5 months. These data clearl
y indiciate that non-lung tissues contain a high proportion of the tot
al body DES+IDES and suggest that pathology in these other pools of DE
S+IDES could result in significant elevation of urinary DES+IDES. Neve
rtheless, the relatively high specific radioactivity of DES+IDES in lu
ng elastin as compared with urine makes monitoring labeled urinary DES
+IDES in this animal model a sensitive tool for assessing elastin degr
adation in experimental lung disease.