Physiologic and morphologic observations of the effects of intravenous elastase on the lung.

Intravenous administration of porcine pancreatic elastase to hamsters produced significant loss of elastic recoil at low volumes. Histology and mean linear intercept of the lungs fixed at a pressure of 20 cm H2O and studied for 3 weeks after administration of elastase were normal. Larger doses of elastase caused immediate fatal, hemorrhagic pulmonary edema. These results confirmed previous morphologic observations of the effects of intravenously administered elastase, but demonstrated that the loss of elastic recoil at low lung volumes is not invariably associated with histologic changes or morphologically with loss of elastin fibers. These observations suggest that submicroscopic lesions may be present and may antedate the earliest morphologic evidence of emphysema and aging in the lung.