Search results
Results from the WOW.Com Content Network
Although α receptors are less sensitive to epinephrine, when activated at pharmacologic doses, they override the vasodilation mediated by β-adrenoreceptors because there are more peripheral α 1 receptors than β-adrenoreceptors. The result is that high levels of circulating epinephrine cause vasoconstriction.
Adrenaline, also known as epinephrine, is a hormone and medication [10] [11] which is involved in regulating visceral functions (e.g., respiration). [ 10 ] [ 12 ] It appears as a white microcrystalline granule. [ 13 ]
The extent of vasoconstriction may be slight or severe depending on the substance or circumstance. Many vasoconstrictors also cause pupil dilation. Medications that cause vasoconstriction include: antihistamines, decongestants, and stimulants. Severe vasoconstriction may result in symptoms of intermittent claudication. [1]
Agonists of alpha-2 receptors in the vascular smooth muscle lead to vasoconstriction. However, in clinical practice drugs applied intravenously that are agonists of alpha-2 receptors such as clonidine lead to powerful vasodilation, which causes a decrease in blood pressure by presynaptic activation of the receptors in the sympathetic ganglia ...
In smooth muscle cells of blood vessels the principal effect of activation of these receptors is vasoconstriction.Blood vessels with α 1-adrenergic receptors are present in the skin, the sphincters [4] of gastrointestinal system, kidney (renal artery) [5] and brain. [6]
Norepinephrine has higher affinity for the α 2 receptor than epinephrine does, and therefore relates less to the latter's functions. [16] Nonselective α 2 agonists include the antihypertensive drug clonidine, [16] which can be used to lower blood pressure and to reduce hot flashes associated with menopause.
The primary endogenous agonists of the sympathetic nervous system are the catecholamines (i.e., epinephrine [adrenaline], norepinephrine [noradrenaline], and dopamine), which function as both neurotransmitters and hormones. Sympathomimetic drugs are used to treat cardiac arrest and low blood pressure, or even delay premature labor, among other ...
The tunica media of the walls of arteries, arterioles, and veins is composed of smooth muscle and causes vasodilation and vasoconstriction. [3] Contraction of smooth muscle cells causes vasoconstriction, and relaxation of smooth muscle causes vasodilation. [1]