Monocrotaline-Induced Pulmonary Hypertension Model

In this study, the monocrotaline model was used, where a single injection of monocrotaline would induce pulmonary hypertension, within 3 to 4 weeks, in rats [26 (link),27 (link)]. To minimize the number of animals used in this study, we performed a preliminary study to determine the lowest effective dosage of monocrotaline that induces pulmonary hypertension. Preliminary data revealed that in rats receiving 60 and 120 mg/kg of monocrotaline (Sigma-Aldrich, St. Louis, MO, USA), the RV/(LV+S) ratios were comparable, and both were significantly higher than those in rats receiving normal saline (p = 0.002 and 0.029, respectively). These data indicated that 60 and 120 mg/kg of monocrotaline exerted similar effects on inducing right ventricular hypertrophy. Thus, we chose to use 60 mg/kg of monocrotaline in this study. In addition, in this study, we administered a daily injection of 100 mg/kg MgSO₄ (Sigma-Aldrich, St. Louis, MO, USA), as our previous data revealed that 100 mg/kg MgSO₄ attenuated the adverse effects of sepsis [44 (link)].