The APJ is a class A, G protein coupled receptors, which coupled with its endogenous ligand apelin is vitally important for human.APJ is shown to be widely expressed in humans, with high levels in the central nervous system, cardiovascular system, adipocytes and many other tissues, and plays an important role in the occurrence and development of cardiovascular and metabolic diseases including atherosclerosis, hypertension, heart failure and diabetes mellitus.Our group study found that exogenous apelin could reduce blood pressure in normal rats, and does not affect heart rate.Further study found that apelin-13 significantly stimulated VSMCs proliferation and increased cell cycle progression for the first time to regulate blood pressure.As APJ is related to hypertension, what people most concerned is that the level change of APJ will produce harmful effects or not.No matter what kind of effects, it requires the appropriate drugs to inhibit or activate APJ.Therefore, the drugs of APJ-related hypertension will be ready to come out.Recently, a certain amount of leading compounds and peptides targeted APJ has been found out, including: peptidic agonists and antagonists;non-peptidic agonists and antagonists.