Figure 11.

Effect of STI571 on rat PA-SMC proliferation (A) and apoptosis (B) in MCT-induced pulmonary hypertension. Medial hypertrophy of pulmonary resistance vessels was associated with an increased number of proliferating vascular cells in MCT-induced pulmonary hypertension. Immunohistochemistry for PCNA (red nuclei are PCNA-positive cells; A) revealed increased proliferation in MCT-challenged animals (as compared with controls). Regression of medial hypertrophy induced by STI571 (50 mg/kg/d) was attributed to reduced SMC proliferation. Apoptosis (assessed by in situ TUNEL assay) was virtually absent in control animals and very low in pulmonary arteries from MCT animals at different time points. Apoptosis (green cells are TUNEL-positive cells; B) was increased in animals treated with STI571. Scale bar: 100 μm. Arrows indicate PCNA- and TUNEL- positive cells in A and B, respectively.