Early Intervention of Tongxinluo () on Right Ventricular Function Assessed by Echocardiography in Rats with Pulmonary Arterial Hypertension Induced by Monocrotaline.

Objective: To investigate the effect of early intervention of Tongxinluo (, TXL) on right ventricular function (RVF) of rats with pulmonary arterial hypertension (PAH) induced by monocrotaline (MCT).

Methods: A total of 30 adult male Sprague-Dawley rats were assigned to 5 groups with complete random experiment design: Sham group (Sham), MCT group, TXL group, sildenafil (SIL) group and combination group (TXL+SIL), 6 rats in each group. Rats were injected with 50 mg/kg MCT solution for inducing PAH model except for those in the sham group. From the day of modeling, rats of TXL, SIL and TXL+SIL groups were given TXL (1.2 g/kg), SIL (10 mg/kg) and combination solution (TXL:1.2 g/kg, SIL: 10 mg/kg) respectively, and rats in Sham and MCT groups were given normal saline (5 mL/kg). The samples were collected and tested after 21 consecutive days of intragastric administration. Echocardiography was used to measure the related indices of RVF, including pulmonary arterial flow spectrum, pulmonary artery diameter (PAD), right ventricular wall thickness (RVWT), right ventricular diameter (RVD), tricuspidannular plane systolic excursion (TAPSE), right atrium transverse diameter (RAT), and inferior vena cava diameter (IVCD). Elastic Verhoeff-Van Gieson staining was adopted to measure the percentage of wall thickness (WT%) of pulmonary arteriols. Hematoxylin-eosin staining was used to measure the cross-sectional area (CSA) of right ventricular cardiomyocytes.

Results: MCT-induced PAH rat model was successfully established. In MCT group the wall of pulmonary arterioles exhibited a prominent-increase thickness, PAD, RVWT, RVD, RAT, IVCD, WT%, right ventricular hypertrophy index (RVHI) as well as CSA of RV cardiomyocyte significantly increased (all P<0.01), and TAPSE markedly decreased (P<0.01). At the same time, TXL prominently improved all of the above indices (all P<0.01). In comparison with SIL, TXL significantly reduced RVD (P<0.05) and decreased CAS of RV cardiomyocytes (P<0.01), but TAPSE in SIL group was much larger than in TXL group (P<0.01). Moreover, TAPSE in TXL+SIL group was larger than that in TXL group (P<0.01), while the two groups performed equally well in terms of the other indices.

Conclusion: Early intervention of TXL could inhibit pulmonary arterioles remodeling, and improve RVF by attenuating right ventricular hypertrophy, and TXL has a stronger effect on inhibiting right ventricular remodeling than SIL.