Project 1: This project will work to understand why women are affected by pulmonary arterial hypertension (PAH) so much more often than men. This observation is true in heritable, idiopathic and associated forms of PAH. While males and females have some similar hormone levels, certain hormones exist at higher levels in each gender. For example, estrogen levels are much higher in females, and thus seemed the most sensible place to start looking for differences that may be affecting disease. In a small, early study of our heritable patients, we found differences in how patients break down estrogens as compared to healthy control subjects. Now, we want to confirm that what we found is true in a much larger group of patients that includes idiopathic and associated forms of PAH. We will also look to see if testosterone and other androgenic hormones are somehow protective for males. If the observation holds true in the larger group of patients, then we may try to "fix" the hormone imbalance in a mouse model of PAH with a drug therapy, and see if it helps improve the mouse pulmonary hypertension without bad side effects to the animals. If the animal drug studies work, then we may be able to try this drug in patients to see if it will work as a human treatment.