OBJECTIVETo establish an easy and repeatable method for determination of pulmonary vascular resistance in normal and pulmonary arterial hypertension (PAH) rats.

METHODSForty-five Sprague-Dawley rats were randomly assigned into three groups: control group, low dose monocrotaline (MCT) group (50 mg/kg) and high dose MCT group (60 mg/kg). Rats in PAH groups received single subcutaneous injection of MCT. We measured pulmonary artery pressure by right heart catheterization using an improved hand-made PE-50 catheter. Cardiac output was calculated through thermodilution method. Pulmonary vascular resistance equals the mean pulmonary artery pressure divided by cardiac output.

RESULTSThe total percentages of success to detect pulmonary artery pressure, cardiac output and pulmonary vascular resistance were 98%, 100% and 96% respectively in 3 groups. Twenty-one days after MCT injection, mean pulmonary artery pressure significantly increased in MCT group compared to control group [(43.1 ± 0.8), (54.8 ± 2.2) vs. (17.4 ± 1.0) mm Hg (1 mm Hg = 0.133 kPa), P < 0.001], and the mPAP was also significantly higher in high dose MCT group than in low dose MCT group (P < 0.001). Cardiac output was significantly lower in PAH rats than in control rats [(77.5 ± 6.9), (71.0 ± 6.7) vs. (126.8 ± 3.9) ml/min, P < 0.001]. Pulmonary vascular resistance was significantly increased in PAH rats compared with control rats [(0.56 ± 0.06), (0.76 ± 0.08) vs. (0.13 ± 0.01) mm Hg×min(-1)×ml(-1), P < 0.001]. There were significant differences in both MCT-treated groups (P = 0.01).

CONCLUSIONSPulmonary vascular resistance in rats could be reliably detected using the improved hand-made PE-50 right heart catheter.