LEP and pulmonary arterial hypertension: In addition, in chronic hypoxia-induced rodent models of pulmonary hypertension (PH), abnormal activation of the Ob/Ob-Rb axis in the pulmonary vascular wall is required for increased leptin secretion by P-ECs and increased Ob-Rb expression in pulmonary artery smooth muscle cells (PASMCs) for PASMC proliferation (18, 19).