Effects of

sympathomimetics outside

cardiovascular system

Domina Petric, MD

Activation of β2-receptors in smooth

musculature of bronchi

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Results inbronchodilatation.

That is why are β2-agonists veryimportant in asthmatreatment.

Healthy Liverpool

In the eye muscle dilator pupillae has α-

adrenergic receptors: effect is mydriasis.

Alfa-receptors stimulators decrease

production and increase drain of occular water

from anterior eye chamber which causes

decrease in the intraocular pressure.

“Base of urinary bladder, sphincter urethrae and

prostate have α1-receptors that cause these

structures to contract and hold urine. Midodrine

(α1-receptor agonist) can cause urine retention.

α-receptors are very important for normal

ejaculation and for cessation of erection after

ejaculation.

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Salivary glands

∙ Salivary glands have adrenoreceptors that

regulate secretion of amilase and water.

∙ Klonidin is an example of sympathomimetic

that causes dry mouth.

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Sweat glands

Adrenalin causes increased

sweating. Activity of

apocrine sweat glands on

the palms is associated

with psychological stress

and those glands do not

participate in regulation of

body temperature.

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Activation of β-receptors in fat tissue

increases lipolysis and release of free fatty

acids and glycerol in the blood. Fat cells also

contain α2-receptors that inhibit lipolysis (by

lowering intracellular cAMP).

Sympatomimetics increase glycogenolysis in

the liver with increased release of glucose in

the circulation.

Metabolic processes

High concentration of catecholamines can

cause metabolic acidosis.

Activation of β2-receptors with endogenous

adrenalin induce potassium ions intracellular

uptake wich causes decrease of potassium

levels in the circulation. This mechanism is a

protection from hyperkalemia during

physical stress and excercise.

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Metabolic processes

∙Activation of beta-receptors in

pancreatic islets causes mild

increase in insulin secretion, whilst

activation of α2-receptors

decreases insulin secretion.

∙Plasma glucose level is the most

important insulin secretion

regulator.

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Other hormones secretion

Activation of β1-

receptors stimulates

renin secretion, whilst

activation of α2-

receptors inhibits

renin secretion.

Adrenergic receptors

modulate parathyroid

hormon, calcitonine,

thyroxine and gastrin

secretion with

moderate significance.

In high

concentration

adrenalin causes

leukocytosis.

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Central nervous system

∙Catecholamines do not pass blood-brain barrier and do

not cause central effects, except in the case of high

speed infusion.

∙Amphetamine passes through blood-brain barrier and

has stimulative effect on the central nervous system.

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