Effect of Papain-Induced Emphysema on Canine Pulmonary Elastin 1

Abstract

Abstract

Experimental emphysema was induced in eight beagles by repeated administration of crude papain via aerosol and intratracheal instillation. Significant increases in mean linear intercept in the lungs of the papain treated dogs were consistent with morphological evidence of ruptured alveolar septa. The proportions of elastin in the parenchymal connective tissue were calculated from the desmosine and isodesmosine content of the total connective tissue and of purified elastin from the same specimens. Mean pulmonary elastin proportions determined 2 weeks after the last dose of papain in four dogs with experimental emphysema were only 4.52% ± 1.84 whereas mean pulmonary elastin proportions in four control dogs were 14.42% ± 3.55. In two dogs sacrificed 3 months after the termination of the insult, mean pulmonary elastin proportions were not significantly different from those in the control dogs. Since the elastolytic activity of papain is very low these data suggest that the elastin may be degraded in vivo by other mechanisms involving enhancement of endogenous elastase activity.