[The expression of tyrosine-kinase receptor flk-1 and hypoxic pulmonary vascular remodeling in the lung of rats exposed to hypoxia].

Abstract

Objective: To assess the role of tyrosine-kinase receptor flk-1 in the development of hypoxic pulmonary vascular remodeling.

Methods: We divided 20 male Wistar rats into two groups(control vs hypoxia) and exposed them to normoxic condition and isobaric hypoxia for 3 weeks respectively. The pulmonary artery pressure was measured by right cardiac catheterization. The expression of flk-1 in lung tissues was measured by immunohistochemical staining. Histologic sections of the lungs were examined by a computerized image analyser.

Results: In hypoxic rats, the pulmonary artery pressure was significantly raised to a higher level, P < 0.01; the cell number of vascular wall was significantly increased. The results also demonstrated that chronic hypoxia brought about the significant increment in thickness of wall with narrowing of lumen of pulmonary arterioles, and the increment in the percent of vascular wall thickness/vascular external diameter (WT%) and the percent of vascular wall area/total vascular area (WA%), P < 0.01. The positive staining of flk-1 in the wall of pulmonary arteriole of rats treated with hypoxia was significantly stronger than that of normal rats, P < 0.01. Positive correlations were seen between the increment of expression of flk-1 with WT% and WA% (r = 0.714, 0.738, P < 0.01).

Conclusion: Chronic hypoxia can induce an increasing expression of flk-1, and the flk-1 may play an important role in the pathogenesis of hypoxic pulmonary vascular remodeling.