The intratracheal injection of pancreatic elastase results in an acute loss of elastin from the lungs of hamsters and the development of emphysema. We used measurements of the unique covalent cross linking amino acids of elastin, desmosine and isodesmosine, to quantitate elastin. Direct measurements on the lungs estimated an average loss of elastin of 57% after elastase injection. Elastin breakdown products were also quantitated in the urine and feces after injection. An average of 8.8 nmol of desmosines was recovered from the urine of each hamster. This amount represented the desmosines from 61% of the elastin lost from the lungs. Desmosine and isodesmosine existed in the urine in peptide fractions that ranged from 9 to 27,000 daltons with an average of 13,000. Only trace quantities of desmosines could be detected in feces. Desmosines injected intraperitoneally were completely recovered in the urine, and radioactive tracer studies failed to reveal in vivo catabolism of injected desmosines. These results suggest that measurement of urinary desmosines holds promise for the study of elastin turnover.
Robert A. Goldstein, Barry C. Starcher