The effect of norepinephrine, amazing effect

It is estimated that many people have heard of norepinephrine for the first time. There is no such word in our daily life. It is estimated that only some patients may know what it is. So what is it used for? In order to let everyone understand it, let me learn about it together. You will have a deeper understanding of it.

Norepinephrine (also known as Noradrenaline, abbreviated as NE or NA), formerly known as "epinephrine", scientific name 1-(3,4-dihydroxyphenyl)-2-amino alcohol is a substance formed by deleting the chemical structure of epinephrine and also belongs to catecholamines.

It is both a neurotransmitter, mainly synthesized and secreted by sympathetic postganglionic neurons and adrenergic nerve endings in the brain, and is the main neurotransmitter released by the latter; it is also a hormone, synthesized and secreted by the adrenal medulla, but in smaller amounts. Norepinephrine in the circulating blood comes mainly from the adrenal medulla.

It mainly stimulates α receptors, has a very weak stimulating effect on β1 receptors, and almost no effect on β2 receptors. It has a strong vasoconstrictive effect, causing the small arteries and veins throughout the body to contract (but the coronary vessels to dilate), increasing peripheral resistance and blood pressure. Its effects on stimulating the heart and inhibiting smooth muscle are weaker than those of adrenaline.

Its clinical application mainly utilizes its pressor effect, and intravenous drip is used for various shocks to improve blood pressure and ensure blood supply to vital organs. The use time should not be too long, otherwise it will cause strong vasoconstriction and tissue hypoxia. The use of phentolamine, which is against excessively strong vasoconstriction, can often increase the blood supply impact of tissues.

Epinephrine is an agonist of α and β receptors. When used, it will increase blood pressure due to the vasoconstriction effect. Phentolamine is an alpha receptor blocker that selectively blocks the alpha receptors associated with vasoconstriction, while the beta receptors associated with vasodilation are not blocked. Therefore, if phentolamine is used immediately after taking epinephrine, a drop in blood pressure will occur, which is called the reversal effect of epinephrine.