Autonomic Nervous System Pharmacology: Key Concepts and Drug Actions

What is the ANS?

A component of the peripheral nervous system that regulates involuntary physiologic processes.

What are five physiologic processes controlled by the ANS?

Heart rate, blood pressure, pupil diameter, respiration, digestion & excretion.

What response does the sympathetic nervous system (SNS) elicit?

Fight or flight response.

How can the parasympathetic nervous system (PNS) be described?

Rest and digest.

What is a ganglion?

A collection of nerve cell bodies.

What neurotransmitter do all preganglionic fibers use?

Acetylcholine.

From which regions of the spinal cord do sympathetic preganglionic fibers exit?

Thoracic, lumbar, and sacral regions.

How do parasympathetic preganglionic fibers exit the CNS?

Via cranial nerves (III, VII, IX, X).

What neurotransmitter is released in the PNS for cardiac and smooth muscle?

Acetylcholine.

What neurotransmitter is released by SNS sweat glands?

Acetylcholine.

What neurotransmitter is released by SNS cardiac and smooth muscle?

Norepinephrine.

What neurotransmitters are released by SNS renal vascular smooth muscle?

Dopamine and norepinephrine.

What type of receptors does acetylcholine act on in ganglion cells?

Nicotinic receptors.

What neurotransmitter do most postganglionic fibers of the SNS use?

Norepinephrine.

What type of receptors do adrenergic neurotransmitters work on?

Adrenergic receptors.

What is the natural ligand for the adrenergic receptor?

Norepinephrine.

What is the effect of alpha 1 receptors?

Smooth muscle constriction, which increases blood pressure.

What do beta 1 receptors increase?

Heart rate and blood pressure.

What do beta 2 receptors cause?

Smooth muscle relaxation.

Which is more potent at alpha-2 receptors: epinephrine or norepinephrine?

Norepinephrine.

Which is more potent at beta-1 receptors: epinephrine or norepinephrine?

Equal.

Which is more potent at beta-2 receptors: epinephrine or norepinephrine?

Epinephrine.

What do adrenergic agents do?

Mimic activation of the SNS by increasing adrenergic receptor activity.

What are direct agonists for adrenergic agents?

Epinephrine, norepinephrine, isoproterenol, albuterol.

What are indirect agonists for adrenergic agents?

Reserpine, tyramine, amphetamine.

What do adrenergic blocking agents do?

Reduce activation of the SNS by blocking the actions of norepinephrine and epinephrine.

What are two classes of medications that block adrenergic activity?

Alpha blockers and beta blockers.

What are five effects of SNS activation?

Increased heart rate, blood pressure, cardiac output, pupil dilation, increased blood flow to brain, heart, and skeletal muscles, increased sweating, increased blood glucose.

What are two drugs that can treat hypotension?

Norepinephrine and phenylephrine.

What are two drugs that can treat cardiogenic shock?

Dopamine and dobutamine.

What are two drugs that can treat cardiac arrest?

Isoproterenol and epinephrine.

What are the three actions of epinephrine that help treat anaphylaxis?

Increases cardiac output, relaxes constricted bronchi.

What type of receptors are nicotinic receptors?

Ionotropic and form a sodium channel.

Where are M1 receptors located?

In the GI tract and glands, causing secretion.

Where are M2 receptors located?

In the heart, specifically the SA and AV nodes, causing decreased heart rate and conduction velocity.

Where are M3 receptors located?

In the eye, lungs, GI tract, bladder, and glands, causing contraction and secretion.

What are five effects of PNS activation?

Decreased heart rate, blood pressure, cardiac output, decreased blood glucose, pupil constriction, increased saliva production.

What can treat dry mouth?

Cholinergic drugs like pilocarpine or cevimeline.

What are cholinesterase inhibitors used for memory disorders?

Donepezil, galantamine, rivastigmine.

What anti-muscarinic drug is used to treat bradycardia?

Atropine.