Bradykinin is a physiologically active peptide consisting of nine amino acids, so bradykinin is a nine-peptide substance belonging to the protein class. The action of kinin-releasing enzyme on kininogen produces three types of peptides, including bradykinin, pancreatic kinin and methylpancreatic bradykinin. Bradykinin is mainly distributed in tissues such as kidney, pancreas and central nervous system, and can be released into the blood. Bradykinin is mainly involved in the regulation of normal physiological processes such as cardiovascular, renal, coagulation, etc. In addition, bradykinin plays a very important role in many pathological processes such as pain, inflammation, hypertension, vascular permeability changes, tumors, etc. Bradykinin can reduce the infarct area of acute ischemia-reperfused myocardium, and has a delayed protective effect on ischemia-reperfused myocardium. In addition, bradykinin acts on blood vessels and causes vasodilation in the body, leading to a decrease in blood pressure in the body.