缺氧对体外培养的肺动脉平滑肌细胞形态及增殖的影响

本实验应用形态学、免疫组化染色，＾３Ｈ－ＴｄＲ掺入、流式细胞等技术探讨缺氧（〈１％Ｏ２和２．５％Ｏ２）对肺动脉平滑肌细胞（ＰＡＳＭ）形态及增殖的影响。结果表明：缺氧２４ｈ使ＰＡＳＭ表型从收缩型向合成型转换，胞浆内ＳＭ－ａ ａｃｔｉｎ减少，线粒体和粗面内质网增多，缺氧４８ｈ以后线粒体肿胀，空泡化，内质网扩张，胞浆内出现髓鞘样结构。流式细胞分析显示缺氧ＰＡＳＭ Ｇ２／Ｍ期细胞比例明显增多（Ｐ〈０．００

EFFECTS OF HYPOXIA ON THE MORPHOLOGY AND PROLIFERATION OF CULTURED PULMONARY ARTERIAL SMOOTH MUSCLE CELL

The effects of hypoxia (2.5% O2 and/or < 1% O2) on bovine pulmonary arterial smooth muscle cell (PASM) proliferation and phenotype change were investigated using immunocytochemical analysis and H- TdR incorporation. The results showed that hypoxia initiated the change of PASM from contractile phenotype to synthetic phenotype. The synthetic phenotype smooth muscle cell was characterized by increase in endoplasmic reticulum and mitochondria, and by decrease in alpha-actin and muscle fiber at the end of 24 h hypoxia. Then the endoplasmic reticulum became dilated, the mitochondria became swollen and myelin figure appeared after 48 h hypoxic exposure. PASM 3H-TdR incorporation was decreased at the end of 6 h hypoxia (P < 0.05), then increased gradually at the end of 12 h. PASM DNA synthesis was significantly stimulated by 24 h hypoxia (P < 0.05). Flow cytometric DNA analysis revealed that hypoxia induced significant enhancement of G2/M phase of PASMs, decreased G0/G1 phase of PASMs (P < 0.001), and only increased S phase of PASMs in 12 h anoxia group (P < 0.05), but decreased S phase of PASMs from 24 h to 48 h (P < 0.001). Immunocytochemical reaction of proliferating cell nuclear antigen (PCNA) in PASM under anoxic condition was more stronger than that of normoxic PASM at 24 h. These results suggest that hypoxia may at first inhibit and then stimulate PASM proliferation and induce phenotype change, which may lead to the development of hypoxic pulmonary hypertension.