Fig. 1.

Vascular remodeling in pulmonary arterial hypertension is manifested by increased pulmonary arterial pressures, decreased arterial compliance, and pruning of the vasculature. At the cellular level, pulmonary arterial adventitial fibroblasts (PAAFs) respond to increased strain, endothelial cells (PAECs) respond to increased flow, and smooth muscle cells (PASMCs) are activated to contract causing vasoconstriction. These cellular responses feedback into the system by increasing extracellular matrix (ECM) stiffness, releasing paracrine factors, and increasing PA pressure, respectively. Images used with permission from J Signal Transduct. 2012: 951497, and sciencellonline.com