APLNR and pulmonary arterial hypertension: In PAH heart in comparison with control, there was a small (≈15%) but significant reduction in apelin receptor density in both LV (PAH 3.42±0.15 fmol/mg, normal 3.96±0.08 fmol/mg; P≤0.05) and RV (PAH 3.5±0.05 fmol/mg, normal 4.24±0.03 fmol/mg, P≤0.001).