Vasodilation is a key phenomenon in maintaining the balance of the body, it consists in the expansion of the lumen of blood vessels, especially arteries. It occurs with the participation of various substances - some produced by the body itself, and some external. The task of vasodilators is to dilate blood vessels.

Vasodilatationis a phenomenon of vasodilation, its effect is a drop in blood pressure, because at a constant volume of circulating blood, the volume of the circulatory system - the reservoir in which blood is located - increases. Smooth muscles in the wall of blood vessels - mainly arteries - are responsible for this effect.

Contents:

  1. Role of vasodilation
  2. Vasodilators - when to use?
  3. Vasodilators - types

Role of vasodilation

Changing the diameter of the vessel, and thus the volume of blood flowing through it, is very important for our body. This process can take place systemically or locally - regulating the blood supply to a specific organ or tissue.

The relaxation of blood vessels occurs when the need for oxygen and nutrients in a given area of ​​the body increases. As a result, it is supplied by a larger blood stream. Vasodilation is responsible, among others, for:

  • blood pressure regulation
  • regulating the body temperature (vasodilation in the skin causes heat dissipation)
  • regulation of blood flow through organs - e.g. vasodilation after exercise or intestines after a meal

Vasodilators - when to use?

Vasodilatorsare substances that cause the expansion of blood vessels: both venous and arterial. This activity is demonstrated by a number of compounds produced by the human body, but also obtained in laboratories. They have different strengths and mechanisms of action. Some of them play a completely different role than vasodilation, and this effect in such cases is not very strong (e.g. papaverine).

What is more, it happens that one substance dilates some vessels and contracts others (e.g. adrenaline and noradrenaline) or the effect depends on the dose - small ones expand and large ones contract (e.g. dopamine).

The use of vasodilators in medicine is a treatment of chronic diseases,treatment among others:

  • hypertension
  • peripheral arterial diseases
  • ischemic heart disease - the so-called angina

They are also used in acute conditions:

  • heart failure
  • pulmonary edema
  • heart attack
  • hypertensive crisis
  • thrower of pregnant

Vasodilators - types

Of course, the selection of vasodilators - their strength and dynamics of action is different depending on the patient's condition. The strongest are:

  • sodium nitroprusside
  • nitroglycerin
  • nikarnidypina
  • enalaprylat
  • fenoldopam
  • urapidyl
  • labetalol

Weaker effective drugs used in the treatment of cardiological diseases (especially hypertension) include:

  • calcium channel blockers (e.g. amlodipine)
  • angiotensin converting enzyme inhibitors (e.g. ramipril)
  • angiotensin receptor blockers (e.g. losartan)
  • adrenergic blockers - so-called new beta-blockers (nebivolol and carvedilol), clonidine
  • some diuretics

Nitroglycerin is also used as an aerosol in ischemic heart disease because it dilates the coronary arteries. Examples of vasodilators with practical use other than vasodilation are: adenosine and papaverine.

Vasodilators produced by the body

Vasodilators produced by the body that are not widely used in medicine include:

  • bradykinina
  • inosine
  • plate activating factor
  • prostacyclin and prostaglandins
  • neurotensin
  • histamine
  • nitric oxide

A special vasodilator is the last of these, because it has a wide variety of effects, such as the effect on memory, digestive tract and platelets. Nitric oxide itself is not used in medicine, but its precursors are widely used - substances that, when absorbed into the body, turn into NO.

It is also worth mentioning about histamine - it is constantly produced by the body in small amounts and in this case it is completely harmless. However, in people with allergic reactions, it is highly overproduced in response to the antigen, which is one of the main factors responsible for anaphylactic shock.

In addition to the substances listed, vascular smooth muscle tone is also regulated by other factors:

  1. autonomic nervous system - it works independentlyour will and regulates the internal economy of the body. The parasympathetic part is responsible for vasodilation
  2. baroreceptors - located in the carotid artery, they cause vasodilation when blood pressure is too high

Vasodilation is the widening of blood vessels that is essential for maintaining balance in the body and for ensuring proper blood distribution. Its opposite is vasoconstriction, i.e. narrowing the lumen of the vessel.

Apart from numerous substances, the baroreceptors and the nervous system are responsible for vasodilation. Some vasodilators have been successfully used in medicine, hence many drugs used in cardiology operate on this mechanism.

About the authorBow. Maciej GrymuzaA graduate of the Faculty of Medicine at the Medical University of K. Marcinkowski in Poznań. He graduated from university with an over good result. Currently, he is a doctor in the field of cardiology and a doctoral student. He is particularly interested in invasive cardiology and implantable devices (stimulators).

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Category:

Cardiology