α-受体阻滞剂可使周围阻力血管和容量血管扩张 ，确保冠状动脉的血流 ，

α- blockers can peripheral resistance vessels and capacitance vessels dilate, to ensure that the coronary blood flow, improving cardiac ejection, not only can effectively lower blood pressure, but also to ensure that the blood perfusion of vital organs and placenta; [beta] by the body can be prolonged atrioventricular junction conduction time, reduce heart rate, to prevent tachycardia, reducing myocardial oxygen consumption. Thus, labetalol through direct action on blood vessels, dilation of blood vessels, reducing blood pressure, but does not affect blood flow to the placenta, but also has anti-platelet aggregation, the maturation of fetal lungs, generally used in severe high pregnancy blood pressure syndrome treatment

Alpha-receptor blockers can make the surrounding resistance blood vessels and capacity blood vessels dilate, ensure the blood flow of the coronary artery, improve the blood flow of the heart, not only can effectively reduce blood pressure, but also ensure the blood perfusion of important organs and placenta; Therefore, Laberel through direct action on blood vessels, there is dilating blood vessels, reduce blood pressure, but does not affect the blood flow of the placenta, but also has anti-platelet coagulation, promote fetal lung maturation role, generally used in the treatment of patients with severe pregnancy hypertension syndrome

α - receptor blocker can dilate the resistance vessels and volume vessels around, ensure the blood flow of coronary artery and increase the cardiac output, not only effectively reduce blood pressure, but also ensure the blood perfusion of important organs and placenta; β - receptor can prolong the conduction time of atrioventricular junction, reduce heart rate, prevent tachycardia and reduce the oxygen consumption of myocardium. Therefore, rabeprolol can dilate blood vessels and reduce blood pressure by directly acting on blood vessels, but it does not affect the blood flow of placenta. It also has the function of anti platelet aggregation and promoting fetal lung maturity. It is generally used in the treatment of moderate and severe pregnancy induced hypertension syndrome<br>