[Alternations of collagen content and collagen gene expression in rat vascular structural remodeling of pulmonary artery induced by hypoxia].

The change of collagen content and procollagen alpha 1 (I), alpha 1 (III) mRNA expression in rat vascular structural remodeling of extrapulmonary artery (EPA) induced by hypoxia were investigated. 72 wistar male rats weighing 200-300g were used and divided into 2 groups: air-breathing group (N group, 39 rats) and hypoxic group (H group, 33 rats exposed to 5000m hypobaric hypoxia for 7 days). Results showed that mPAp, Rv/(Lv+s), the wet, dry weights and hypoxyproline (HP) content in EPA of H group were increased from 2.83 +/- 0.09kPa (mean +/- smean), 0.23 +/- 0.01, 5.2 +/- 0.2mg, 1.7 +/- 0.1mg and 22.3 +/- 1.0 micrograms)/100g BW (body weight) to 4.77 +/- 0.12kPa, 0.43 +/- 0.01, 10.5 +/- 0.5mg, 4.1 +/- 0.2mg and 58.4 +/- 3.4 micrograms/100g BW (body weight) to 4.77 +/- 0.12kPa, 0.43 +/- 0.02, 10.5 +/- 0.5mg, 4.1 +/- 0.2mg and 58.4 +/- 3.4 micrograms/100g (all P < 0.01). Dot Blot and Northern Blot hybridization analyses showed that in EPA of H group procollagen alpha 1(I) and alpha 1(III) mRNAs were increased 154% and 177% (all P < 0.05). Histological study (HE) showed that hypoxia could induce an increase in the wall thickness of EPA, particularly in adventitial thickness of the pulmonary arterial trunk. Electron microscopy revealed the hypertrophied medial smooth muscle cells containing a significant increase in rough endoplasmic reticulum (RER), in extracellular ground, collagen fibers and elastin were increased. In adventitia, the fibroblasts showed both hypertrophy and hyperplasia and surrounding collagen fibers were increased. These studies suggested that fibroblast might play important role in the remodeling of EPA during the early hypoxic pulmonary hypertension and the increase of collagen gene expression might be involved in the mechanism of collagen content and remodeling of EPA induced by hypoxia.