The Effect of Elastase on Pulmonary Elastin and Collagen: Comparison of Intravenous and Intratracheal Exposure

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Abstract
Intravenous injection of exogenous pancreatic elastase to hamsters within tolerable limits (up to 133 unitsi/100 g animal) induced no significant changes in lung elastin as compared with the controls whereas intratracheal injection of a much smaller amount of enzyme (5 units) caused a remarkable decrease in total elastin within 24 hr. Decrease in lung collagen is observed by both routes of elastase injection only at the highest tolerable level of enzymes utilized (28 U IT and 133 U IV). The large differences in the tolerable limits of IV and IT injections of elastase may be ascribed to large differences in dilution volumes encountered in the vascular circuit as compared to the airways and to the nature and amounts of elastase inhibitors in serum as opposed to pulmonary fluid. Collagenase impurities in the elastase may also be in part responsible for the observed biochemical changes in lung collagen.