APLNR and pulmonary arterial hypertension: Studies have confirmed that APJ receptors play an important role in the physiological and pathological processes of the cardiovascular system and participate in a variety of cardiovascular diseases, such as atherosclerosis, coronary heart disease, pulmonary hypertension (PAH), hypertension, myocardial ischemia and reperfusion injury (Huang et al., 2019)[3].