[Pulmonary emphysema induced by elastase: influence of the dose and effect of added collagenase]

The endotracheal deposition of pancreatic porcine elastase (EPP) at 40 u X kg-1 body weight provokes a typical pulmonary emphysema (alveoli disruption) in rats. This emphysema is significant (p less than 0.001) when quantitatively compared to a placebo (100% increase of the mean linear intercept, ILM). The EPP-treated lungs are very heterogeneous and the size of the alveoli vary as much as 30% versus 19% in controls. The emphysema is more effective at a 80 u X kg-1 dose and the individual disparities are reduced (dose effect). When bacterial collagenase (200 u X kg-1 body weight) is added to EPP, the pulmonary abnormalities (disruptions, ILM) are in no way increased (no enzymatic synergy, repair by collagenesis?). In contrast, alveolar dilation is slightly reduced 8 weeks after enzyme administration (p less than 0.05): EPP is not altered in vitro by collagenase and despite several hypothesis, the moderating effect of collagenase in vivo still remains unexplained. This result suggests that the joint presence of several proteases is not necessarily an aggravating factor in the etiopathogenesis of emphysema.