A nerve, agent or substance that narrows blood vessels.
An agent that narrows blood vessel openings, restricting the flow of blood through them
n. an agent that causes narrowing of the blood vessels and therefore a decrease in blood flow. Vasoconstrictor drugs are alpha agonists (see sympathomimetic): they are used to raise the blood pressure in disorders of the circulation, shock, or severe bleeding and to maintain blood pressure during surgery (e.g. *ephedrine, *metaraminol, *phenylephrine). Some vasoconstrictors (e.g. ephedrine, *xylometazoline) have a rapid effect when applied to mucous membranes and may be used to relieve nasal congestion. If the blood pressure rises too quickly headache and vomiting may occur. A vasoconstrictor is often added to local anaesthetic solutions used in dentistry to prolong their effectiveness.
an agent which causes narrowing of the blood vessels.
Vasoconstrictor sympathomimetic drugs, such as EPHEDRINE and NORADRENALINE, raise the BLOOD PRESSURE temporarily by acting on receptors that constrict peripheral blood vessels. They are occasionally used as a quick way of raising blood pressure when other measures have failed, but they have potentially serious side-effects on the kidney. Vasoconstrictors are also used with local anaesthetics (see under ANAESTHESIA) to counteract the latter’s vasodilator e?ect. Adrenaline will reduce local blood ?ow, slow the absorption of anaesthetic and prolong its e?ect.... vasoconstrictors
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