Abstract:OBJECTIVE: Pulmonary hypertension is a proliferative vascular disease characterized by pulmonary vascular structural remodeling.Until now,the pathogenesis of pulmonary hypertension has not been fully understood. Recent many studies have suggested that endogenous vascular elastase plays a pivotal role in the vascular changes associated with pulmonary hypertension.The study aimed to explore the relationship between elastolytic activity and pulmonary remodeling in rats with pulmonary hypertension induced by monocrotaline. METHODS: One hundred mature Sprague-Dawley rats were randomly assigned into Normal and Model groups (both n=50). Rats in the Model group were induced with pulmonary hypertension by subcutaneous injection of monocrotaline (60 mg/kg). The elastolytic activity was measured by a fluorescence microplate reader and the pulmonary artery pressure was detected by catheterization at 2, 8,14 and 21 days post-injection. Light microscopic structural analysis of the peripheral pulmonary vasculature was performed at the same time points. RESULTS: The elastolytic activity increased significantly to(3.87±0.19)×10~(-8) U/mg at 2 days, and then decreased to (0.18±0.2)×10~(-8) U/mg at 8 days after injection, but on the 14th day it increased again to(1.45±(0.18)×)10~(-8) U/mg and remained high at (1.91±0.18)×10~(-8) U/mg on the 21st day.The extension of muscle into distal arteries was observed on the 8th day post-injection.Increased pulmonary artery pressure and medial wall thickness were present on the 14th day post-injection. CONCLUSIONS: The early increase in the elastolytic activity may be related to the initiation of pulmonary hypertension.The second increase may be involved in the development of this disease.
