2.1. Animals and Groupings

Fourteen male Sprague Dawley (SD) rats, aged five weeks and weighing between 180and 210 g, were obtained from Beijing Vital River Laboratory Animal Technology Co., Ltd. Beijing, China. SD rats were housed in a controlled environment free from specific pathogens (SPF) at Beijing Chaoyang Hospital. Following a week of adaptive nourishment within a controlled animal enclosure, PAH was triggered through intraperitoneal administration of MCT at a dosage of 60 mg/kg (provided by Sigma-Aldrich Co. LLC, St. Louis, MO, USA). The MCT powder was mixed with a solution containing ethanol and saline, with a ratio of 2 to 8. The rats were divided into two groups, namely the control (CON) group that received the solvent injection (n = 7), and the MCT-PAH group that received the MCT injection (n = 7), in a random manner. Four weeks after MCT injection, echocardiography was performed. Subsequently, the rats were anesthetized by pentobarbital sodium (40 mg/kg) and sacrificed for hemodynamic measurements.

This research was carried out in accordance with the ethical standards set by the Animal Experimentation Ethics Committee of Capital Medical University, Beijing, China (AEEI-2022-011), and followed the current National Institutes of Health (NIH) guidelines for animal welfare and experimental protocols and conducted following ethical guidelines approved by the Animal Experimentation Ethics Committee of Capital Medical University, Beijing, China (AEEI-2022-011), and adhered to current NIH guidelines for animal care and experimental procedures.