AIMTo investigate the effects of hypoxia on the proliferation and apoptosis of PASMC, to evaluate the role of iNOS protein expression and ADM on the hypoxic pulmonary hypertension (HPH) pathogenesis.

METHODSTo culture rat pulmonary artery smooth muscle cell (PASMC), cultured PASMC cells were grouped into: normoxic group; hypoxic group; hypoxia + L-NAME group; hypoxia+ ADM group. Proliferation of PASMC were investigated by MTT and PCNA. Apoptosis of PASMC were examined by flow-cytometry. Westen blot was used to measure protein expression of iNOS induced by hypoxia.

RESULTS(By MTT, the value of 24 h hypoxia was significantly higher than that in the normoxic group (P < 0.01), the value of the hypoxia + ADM was significantly lower than that in hypoxia group, the value of the hypoxia + L-NAME was significantly higher than those of hypoxic group and normoxic group (P < 0.01). (2) By immunohistochemistry, PCNA was poorly positive in PASMC, whereas positive after 24 h hypoxia (P < 0.01), ADM inhibited the expression of PCNA significantly (P < 0.01), whereas L-NAME increased the expression of PCNA significantly (P < 0.01). (3) By FCM, apoptosis index was not significantly different between the normoxic group, hypoxic group, hypoxia + L-NAME and hypoxia + ADM (P > 0.05). (4) By Western blot, iNOS expression was poorly positive in control group, positive after 4 h hypoxia (P < 0.01), increasing as the hypoxia environment continued (P < 0.01). L-NAME had no effect on iNOS protein, ADM promoted iNOS expression (P < 0.01).

CONCLUSION(1) Hypoxia stimulates the proliferation of PASMC, and has no obvious effects on the apoptosis of PASMC. (2) Hypoxia induces the expression of iNOS, ADM can increase expression of iNOS, ADM and INOS plays a role of protection in HPH pathogenesis.