RecruitingPhase 1Clinical trialStudy of Intravenous ZMA001 in Healthy SubjectsBackground: A number of diseases can cause a type of lung injury called pulmonary arterial hypertension (PAH). Most people who develop PAH do not survive more than a few years. A new study drug (ZMA001) may help. ZMA001 is a monoclonal antibody. This type of drug consists of proteins, made in a facility, that are very similar to proteins in a human body. But before giving ZMA001 to people sick with PAH, researchers want to find out how the drug affects healthy people. Objective: To test a drug (ZMA001) in healthy volunteers. Eligibility: Healthy adults aged 18 to 60 years. Design: Participants will be screened. They will have a physical exam with blood tests. They will have a urine test for drug use. They will have a test of their heart function. Participants will come to the clinic for 1 inpatient visit of up to 48 hours. ZMA001 is a liquid administered through a tube attached to a needle inserted into a vein in the arm. Participants will receive this drug only once, during their inpatient stay. Some participants will receive the drug; others will receive a placebo in Cohort 1 only. A placebo is a treatment that looks just like the real drug but contains no medicine. Participants will not know which treatment they are getting in Cohort 1. Cohorts 2-4 will receive a single dose of the study drug, administered through a tube attached to a needle inserted into a vein in the arm. After a screening visit, participants will have 1 inpatient visit and up to 8 outpatient visits over 16 weeks after receiving the treatment. Blood draws and other tests will be repeated. Each outpatient visit is approximately 2 hours long. This study is the first time ZMA001 will be administered to people.