Experimental emphysema following one intravenous infusion of trypsin

This study was undertaken to investigate the effects of a deficit in protease inhibitor (AT) induced by intravenously administered trypsin on the development of elastase-induced emphysema. Rats receiving a perfusion of trypsin (4.5 mg/kg body wt) intravenously (TIV rats) or one instillation of elastase (92 IU/subject) into the trachea (ELAS rats) were compared with rats receiving both trypsin and elastase (TIVELAS rats). Compared with 8 sham-injected rats, the serum AT activity of 14 TIV rats decreased slightly (5.5%) 150 min after the beginning of the perfusion. In six other TIV rats sacrificed early after the perfusion, a granulocyte sequestration with edema and vascular thrombi demonstrated early lung injury. Anatomical studies of lung and determination of the mean linear intercept (MLI) were carried out 56 days after the administration of the enzymes. Emphysema was confirmed by a significant (P less than .001) MLI increase (about 150 microns) in 22/24 TIV, 20/21 ELAS, and 21/21 TIVELAS rats in comparison with 40 control rats (78 microns). These similar results of the treated rats show that trypsin did not worsen elastase-induced emphysema and also indicate that trypsin given intravenously alone induces emphysema as does elastase when introduced into the airways. The AT activity decrease consequent to proteolysis by trypsin and pulmonary leucostasis may contribute to this trypsin-triggered emphysema.