Adrenergic nervous system

The modern usage of P2" go Asts for the treatment of asthma dates to 1903 when the effect of injected epinephrine [51-43-4] (adrenaline) C2H23NO2, (1 R = CH3) was investigated (see Epinephrine and norepinephrine) (33). As in some other modem treatments, eg, xanthines and anticholinergics, the roots of P2" go Ast therapy for asthma can be found in historical records which document the use of herbal extracts containing ephedrine [299-42-3] C qH NO, (2) as bronchodilators. Epinephrine and ephedrine are stmcturaHy related to the catecholamine norepinephrine [51-41-2] CgH NO, (1, R = H), a neurotransmitter of the adrenergic nervous system (see Neuroregulators). 

Division of the receptors in the adrenergic nervous system into two classes (a and P) was proposed in 1948 (39) when a difference in the rank order of potency of epinephrine (1, R = CH ), norephinephrine (1, R = H), and isoproterenol [7683-59-2], C H yNO, (1, R = CH(CH3)2) was noted to depend on the organ examined. Eurther subdivision into groups P2 proposed in 1967 (40). Both types of P-adrenoceptors are found throughout the... 

The sympathetic or adrenergic nervous system operates in juxtaposition to the parasympathetic nervous system to maintain homeostasis in response to physical activity and physical or psychological stress. Sympathomimetic neurotransmission is generally mediated by norepinephrine [51-41 -2] (1), CgH NO, released from presynaptic storage granules upon stimulation. A second endogenous sympathomimetic agent, epinephrine [51-43-4] (2),... 

The primary effects of angiotensin II ate (/) produciag vasoconstriction directiy or iadirectiy through activation of the adrenergic nervous system ... 

Factors which have been considered responsible for this hemodynamic alteration are heredity, salt and water, the adrenergic nervous system and the renin-angiotensin system. 

Adrenergic blocking agents, 241 Adrenergic nervous system, 62 Adrenosterone, 176 Agonists, 20 Aldosterone, 206 Allergen, 41... 

While there may be some involvement of the adrenergic nervous system in primary hypertension, there is no clear evidence that a malfunction of this system is causally involved in primary hypertension. Therefore, even though drugs may depress the sympathetic system and thus lower blood pressure, it should not be assumed... 

B. The symptoms of thyrotoxicosis are largely mediated through the adrenergic nervous system, and 3-adrenoceptor blockers may ameUorate some of... 

Antihypertensive Agents. Hypertension (high blood pressure) is a significant risk factor for cardiovascular diseases such as angina heart attacks, and strokes. /(-Adrenoceptor (adrenergic nervous system receptors of the /(-type) antagonists (/(-blockers), calcium channel blockers, angiotensinconverting enzyme (ACE) inhibitors, and potassium channel activators... 

Central Nervous System Stimulants Central nervous system stimulants include agents such as the amphetamines (Dexedrine) and methylphenidate hydrochloride (Ritalin), used to elevate mood, suppress appetite, and control hyperkinetic disorders in children. Other examples include the illegal drugs methamphet-amine and cocaine. The mechanism of action of these drugs is to augment actions of the adrenergic nervous system. 

Amphetamine (3) is orally active and, through an indirect mechanism, causes a general activation of the adrenergic nervous system. Unlike (l)and (2), amphetamine readily crosses the blood-brain barrier to activate a number of adrenergic pathways in the central nervous system (CNS). Amphetamine s CNS activity is the basis of its clinical utility in treating attention-deficit disorder, narcolepsy, and use as an anorexiant. These therapeutic areas are treated elsewhere in this volume. 

The catecholamines belong to a family of bioamines and are secretory products of the sympathoadrenal system, which are required for the body to adapt to a great variety of acute and chronic stresses. Epinephrine (80-85% of stored catecholamines) is synthesized primarily in the cells of the adrenal medulla, whereas norepinephrine (15-20% of stored catecholamines) is synthesized and stored not only in the adrenal medulla but also in various areas of the central nervous system (CNS) and in the nerve endings of the adrenergic nervous system. Dopamine, another catecholamine, acts primarily as a neurotransmitter and has httie effect on fuel metabolism. 

The sympathetic adrenergic nervous system plays a major role in the regulation of arterial pressure. Activation of these nerves to the heart increases the heart rate (positive chronotropy), contractility (positive inotropy), and velocity of electrical impulse conduction (positive dromotropy). Within the medulla are located preganglionic sympathetic excitatory neurons, which travel from the spinal cord to the ganglia. They have significant basal activity, which generates a level of sympathetic tone to the heart and vasculature even under basal conditions. The sympathetic ... 

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