Vasodilator


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vasodilator

[¦vā·zō′dī‚lād·ər]
(physiology)
A nerve or an agent that causes blood vessel dilation.

Vasodilator

 

one of a group of pharmacological agents that cause the smooth muscles of blood vessels to relax, which results in the widening of vascular lumens. Several groups of vasodilators are distinguished according to their mechanism of action and chemical structure.

Myotropic agents directly affect the muscular elements of the vascular wall, altering the metabolic processes and decreasing the tone of the elements. They include such purine derivatives as caffeine and theophylline, such isoquinoline derivatives as papaverine, drotaverine, salsoline, and such chromone derivatives as kellin.

Neurotropic agents exert a vasodilative effect through their influence on the neural regulation of vascular tone. They may have peripheral or central action. Those with peripheral action include adrenolytic agents, which block the adrenergic receptors of blood vessles (for example, phentolamine), and sympatholytics, which block the transmission of excitation from the endings of the sympathetic nerves that innervate blood vessels (for example, oktadin and ornid).

Other vasodilators include cholinomimetic and ganglion-blocking agents. The former, which include acetylcholine and carba-chol, facilitate the transmission of excitation from parasympathetic nerves to effector organs, including blood vessels. The latter, which include Tetamon (sympatektoman), Hexonium (esametina), and pentamin, impede the transmission of excitation in the sympathetic ganglia, resulting in a decrease in vascular tone. Derivatives of hydrazinophtalazine (for example, Apressin [Ap-resoline]), and of phenothiazine (for example, aminazine), affect the central regulation of vascular tone.

Some drugs have a mixed mechanism of action and may be centrally neurotropic and peripherally myotropic. These drugs include nitrites and nitrates (amyl nitrite, nitroglycerin, nitranol) and reserpine, which is an alkaloid isolated from the tropical plant rauwolfia. Reserpine weakens the central and peripheral adrenergic innervation of blood vessels, causing the vascular lumens to dilate and arterial pressure to decrease.

Vasodilators are used mainly in the treatment of ischemic heart disease, hypertension, and cerebrovascular disorders. They are also used in surgery to reduce bleeding (by lowering arterial pressure). Many vasodilators also have other pharmacological effects.

REFERENCES

Kaverina, N. V. Farmakologiia koronarnogo krovoobrashcheniia. Moscow, 1968.
Mashkovskii, M. D. Lekarslvennyesredstva, 7th ed., part 1. Moscow, 1972.
Hoobler, S. W., and A. S. Dontas. “Drug Treatment of Hypertension.” Pharmacological Reviews, 1953, vol. 5, no. 2.

V. V. ZAKUSOV

References in periodicals archive ?
While conventional vasodilator strategies appeared to be of limited benefit, the combination of immunosuppression and IVIG was associated with improvement and eventual recovery.
TRADITIONAL USES: Antioxidant and peripheral vasodilator (brain support, cerebrovascular disorders, neuroprotection and tinnitus).
The survival rate of neonates suffering from PPHN has been improved by the use of high-frequency oscillatory ventilation (HFOV), selective pulmonary vasodilators such as iNO and phosphodiesterase inhibitors (sildenafil and milrinone), surfactant and extracorporeal membrane oxygenation (ECMO).
Park, "Efficacy of pulmonary vasodilator therapy in patients with functionally single ventricle," International Heart Journal, vol.
Therefore, vasodilators and rheological factors might have a positive influence on hearing recovery by increasing the caliber of the blood vessels and cochlear microcirculation.
Treadmill, bicycle ergometer has some peculiarities because the patient has to perform maximum physical stress apart from vasodilator effects of adenosine.
Therapy with vasoactive agents, including vasopressors, inotropes, and vasodilators, is prescribed to correct abnormal vascular tone, and/or to improve cardiac output (CO) in order to restore tissue perfusion and normalize oxygen consumption.
Papaverine has been used for a number of different vasospastic and vascular disorders, but its efficacy appears to var y under different situations.5 The possible therapeutic efficacy of its vasodilator effect has been investigated in many studies on wound healing and aneurysm surgery.5,6 However, the affinity of papaverine for different vasoconstrictor substances has not yet been clarified, so the interaction between the vasospastic agents and papaverine remains unknown.
The aqueous-methanolic extract of Ocimum basilicum, Linn was subjected to in vitro investigations for its possible antispasmodic, bronchodilator and vasodilator activities.
Statistical analysis on these findings produced a combination index (Cl) of 1.041 at [ED.sub.50], which indicates the two herbs produced additive vasodilator effects when used as a combined decoction.
However, other studies failing to significantly alter FMD with L-NMMA [8-10] indicate potential involvement of additional vasodilators (such as vasodilator prostanoids (PN) [11] and endothelium-derived hyperpolarizing factor (EDHF) [12, 13]).
Inhaled aerosolized prostacyclin as a selective pulmonary vasodilator for the treatment of severe hypoxaemia.