What Is an Adrenoceptor?

It is a type of tissue receptor that mediates the action of catecholamines and is G-protein coupled. According to its different response to norepinephrine, it is divided into adrenergic alpha receptors and beta receptors. Relatively speaking, norepinephrine is more sensitive to the effect of alpha receptors than epinephrine, while epinephrine is more sensitive to the effect of beta receptors. Skin, kidney, and gastrointestinal vascular smooth muscle are mainly receptors, skeletal muscle, liver vascular smooth muscle and heart are mainly receptors, and there are mainly distributed in the kidney and mesenteric vascular system and some areas of the central nervous system. Dopamine adrenergic receptor.

Adrenergic receptors are found in various organs that undergo fiber domination after sympathetic ganglia.

Adrenergic receptors can be distinguished by their effect on catecholamines. Receptors showed a titer of norepinephrine> epinephrine> isoproterenol. These receptors are called only receptors; the titer of the receptor was isoproterenol> adrenal. For those who are> norepinephrine, these receptors are called B receptors. Receptors that only respond to dopamine are dopamine receptors ^[1]

Adrenergic receptors can be divided into two types of and by the method of responding to drugs. Epinephrine acts on both alpha and beta receptors and has a strong effect, while norepinephrine mainly acts on alpha types. The smooth muscle effects produced by the combination of alpha receptors with catecholamines are mainly vasoconstriction, pupil dilation, uterine contraction, and iris-assisted contraction, but there are also inhibitory ones, such as small intestinal diastole. Alpha receptors can be inhibited by alpha blocking drugs such as dibenamine and ergot poison. The response caused by receptors is bronchiectasis, vasodilation, etc. receptors can be inhibited by blocking drugs such as 3,4-dichloroisoproterenol (D-CI).

Adrenergic receptors can be divided into two categories, and .

Alpha receptors are divided into 1 and 2.

1 is distributed on the presynaptic membrane and vascular smooth muscle. It mainly causes vasoconstriction when excited. Blocker: prazosin. 2 is mainly distributed on the presynaptic membrane of noradrenergic nerves. It excites NE during excitement. Generate negative feedback to regulate the inhibitory effect, blocker: yohimbine.

Beta receptors are divided into 1, 2, and 3.

1 and 3 are mainly distributed on myocardial cells. The activation of 1 receptors can have a positive effect on the myocardium, leading to a series of responses to myocardial excitement, such as: increased contraction, faster ejection of the heart, increased heart rate, etc. Blocking agents: Propranolol and atenolol; 3 receptor activation can produce negative inotropic effects, which may be involved in the pathophysiology of heart failure. 3 receptors cause negative inotropic effects through inhibitory G proteins, and may also be mediated through the nitric oxide pathway. 2 receptors are mainly distributed on smooth muscles, such as vascular smooth muscles, digestive tract smooth muscles, bronchial smooth muscles, etc., and this receptor can cause smooth muscle relaxation after being stimulated. Blocking agent: Nadorol ^[1] .