Treprostinil (300 ng/kg/min, osmotic minipumps), alone or in combination with metformin (300 mg/kg, drinking water), was given 7 weeks after a single injection of SU5416 (100 mg/kg) to obese ZSF1 rats. A, Seven weeks after the treatment, lung tissue sections were subjected to pulmonary artery (PA) medial wall thickness (MT) analyses. Scale bar = 50 μm. 40X. B, Effects of treprostinil and/or metformin on AMPK activation in the RV were detected by Western blot analyses. Data are mean ± SEM; n = 3–5 rats/group; *P < 0.05 vs. Ln-Su and #P < 0.05 vs. Ob-Su.