The aim of this project is to find molecular targets of DHEA in pulmonary arterial smooth muscle cells under hypoxia during thirty minutes until twenty-four hours. This work has begun after previous works showing that DHEA decreases Pulmonary Arterial Hypertension (PAHT) in rat under hypoxia (10% oxygen). We use smooth muscle cells knowing that they are first workers in contraction of pulmonary arteries. Hypoxia is realized in two ways: in decreasing oxygen concentration, in this case it's called "gas hypoxia ", or in treating cells with agents increasing accumulation of the alpha subunit of the oxygen sensor "HIF 1" (Hypoxia Inducible factor), in this case it's called "chemical hypoxia". We show that treatments with DHEA decrease accumulation of HIF 1 alpha in chemical hypoxia (with deferoxamin). Those results show a rapid effect after thirty minutes and this effect is maximum at 50µM of DHEA. This study will make it possible to better know the mechanisms of action of DHEA within the framework of the treatments for people treated for respiratory insufficiencies.