抄録
Rabbits fed on a 1% cholesterol diet for 18 weeks were daily injected i. m. with porcine pancreatic elastase (10mg/rabbit/day). The enzyme activity in serum toward Suc-(Ala)3-pNA, a synthetic substrate of elastase, was significantly higher in elastase-administered rabbits for periods of 18 weeks. This activity was considered as an elastase activity because elastatinal, a specific inhibitor of elastase, strongly inhibited not only the enzyme activity in serum but also the activity of porcine pancreatic elastase used for administration. Orceinelastin hydrolyzing activity was lower than Suc(Ala)3-pNA hydrolyzing activity in sera of elastase-administered rabbits and a level of α2-macroglobulin, an inhibitor of elastase, was elevated in these sera. This result may suggest that elastase forms a complex with α2-macroglobulin, a high-molecular-weight inhibitor in serum and indicate that its complex is slightly active on the high-molecular-weight substrate, elastin, but retains to some extent the activity on the lowmolecular-weight substrate, Suc-(Ala)3-pNA. Elevated serum lipids were lowered, especially on the 18th week, by elastase administration. On the 18th week, furthermore, there was a decrease in lipids in aortic tissue and elastin fraction from elastase-administered rabbits. In particular, a decrease in the content of lipids in elastin fraction was significant. This decrease in elastin-bound lipids may be a result of proteolytic action of elastase against lipid-bound elastin, probably denatured one. Scanning electron microscopic study on the endothelial surface of rabbit aorta showed a reduction or regression of plaques in elastase-administered rabbits.
