[Effect of hypoxia on angiotensin-converting enzyme activity and gene expression of intrapulmonary artery smooth muscle cells].

In order to observe the effect of hypoxia on pulmonary artery smooth muscle cells (PASMC), angiotensin-converting enzyme (ACE) activity was measured by colometry and the expression of ACE mRNA was detected by Northern blot, using rabbit isolated and cultured PASMC. The main results are as follows: (1) under normoxia both ACE activity and gene expression could be detected in PASMC; and (2) the expression level of ACE mRNA, after an initial latent period of 6 h hypoxia, began to show a marked increase with time in the next 12, 24 and 48 h. Exposure to hypoxia for 24 h resulted in an increase in either culture medium or cell ACE activity, as compared with that under normoxia. The results suggest that PASMC ACE increased by hypoxia might play an important role in the development of hypoxic pulmonary hypertension.