CFZ decreases RV pressure in PAH rats and increases the susceptibility of vasodilators to reduce RV pressure. PAH rats (SU5416/ovalbumin) were injected with CFZ (6 mg/kg body weight), twice a week. Three days after the last injection, rats were anaesthetized and mechanically ventilated. A Millar catheter was inserted into the RV apex to record RV pressure. After stabilization of haemodynamic recording for 10 min, sodium nitroprusside (SNP; 10, 20, or 50 μg/kg body weight) was slowly administered through the jugular vein in a 100 μL injection volume. (A) Representative homodynamic recording. (B) The bar graph represents means ± SEM of RV systolic pressure (DMSO, n = 6; CFZ, n = 5). (C) The bar graph represents means ± SEM of the heart rate. (D) The bar graph represents means ± SEM of Fulton index. *P< 0.05.