Drugs and the Parasympathetic Nervous System

Question 1

Decide whether each of the clinical uses listed below should be classified under muscarinic receptor agonism or antagonism.

Pilocarpine and cevimeline that stimulate salivation and lacrimation in patients with a dry mouth or eyes, secondary to irradiation or Sjögren’s syndrome

Answer 1

Muscarinic receptor agonist

Question 2

Decide whether each of the clinical uses listed below should be classified under muscarinic receptor agonism or antagonism.

Darifenacin used in the treatment of urinary incontinence to relax the bladder

Answer 2

Muscarinic receptor antagonist

Question 3

Decide whether each of the clinical uses listed below should be classified under muscarinic receptor agonism or antagonism.

Tiotropium and ipratropium used as bronchodilators for the treatment of asthma and COPDilation to facilitate ophthalmoscopic examination

Answer 3

Muscarinic receptor antagonist

Question 4

Decide whether each of the clinical uses listed below should be classified under muscarinic receptor agonism or antagonism.

Pilocarpine eye drops that cause a reduction in intraocular pressure and are used in the treatment of glaucoma

Answer 4

Muscarinic receptor agonist

Question 5

Decide whether each of the clinical uses listed below should be classified under muscarinic receptor agonism or antagonism.

Agents used to reduce salivation and bronchial secretions as premedication for anaesthesia

Answer 5

Muscarinic receptor antagonist

Question 6

Decide whether each of the clinical uses listed below should be classified under muscarinic receptor agonism or antagonism.

Agents used for pupillary dilation to facilitate ophthalmoscopic examination

Answer 6

Muscarinic receptor antagonist

Question 7

The parasympathetic system:

Has minimal effect on the bronchial tree

Answer 7

False. The parasympathetic system stimulates bronchoconstriction.

Question 8

The parasympathetic system:

Increases heart rate

Answer 8

False. The parasympathetic system slows the heart.

Question 9

The parasympathetic system:

Relaxes the bladder

Answer 9

False. The parasympathetic system contracts the bladder.

Question 10

The parasympathetic system:

Stimulates erection and ejaculation

Answer 10

False. The sympathetic system controls ejaculation.

Question 11

The parasympathetic system:

Constricts the pupil

Answer 11

True

Question 12

The parasympathetic system:

Increases gastric secretion

Answer 12

True

Question 13

Regarding the neurotransmitters that affect the parasympathetic nervous system:

Ganglionic receptors are exclusively nicotinic

Answer 13

False. Neurotransmission at autonomic ganglia is predominantly nicotinic, but muscarinic receptors are present and increase excitation.

Question 14

Regarding the neurotransmitters that affect the parasympathetic nervous system:

Botulinism results from the toxin preventing synthesis of acetylcholine

Answer 14

False. Botulism prevents the release of the acetylcholine stores.

Question 15

Regarding the neurotransmitters that affect the parasympathetic nervous system:

Neurotransmission in the parasympathetic system is terminated by re-uptake of transmitter

Answer 15

False. The parasympathetic neurotransmitter is ACh and its effects are terminated by metabolism, not re-uptake.

Question 16

Regarding the neurotransmitters that affect the parasympathetic nervous system:

The main neurotransmitter throughout the parasympathetic system is acetylcholine

Answer 16

True

Question 17

Regarding the neurotransmitters that affect the parasympathetic nervous system:

Peripheral benzodiazepine receptors are an important site of modulation for the parasympathetic system

Answer 17

False. The benzodiazepine receptor may influence central control of the the autonomic system, but there is no peripheral effect.

Question 18

Regarding the neurotransmitters that affect the parasympathetic nervous system:

ATP and VIP are examples of NANC transmitters

Answer 18

True

Question 19

Regarding drugs clinicians use to affect parasympathetic activity:

Anticholinergic eye drops can be used to treat glaucoma

Answer 19

False. Anticholinergic drugs dilate pupils to facilitate ophthalmic examinations, but they increase intraocular pressure. Cholinergic agonists are used to treat glaucoma.

Question 20

Regarding drugs clinicians use to affect parasympathetic activity:

Muscarinic antagonists can be used to treat urinary incontinence

Answer 20

True. The selective M3 antagonist darifenacin is used to treat urinary incontinence.

Question 21

Regarding drugs clinicians use to affect parasympathetic activity:

Quaternary ammonium muscarinic antagonists do not affect the eye

Answer 21

False. The effects of quaternary ammonium muscarinic antagonists on the eye are mediated through the peripheral nervous system.

Question 22

Regarding drugs clinicians use to affect parasympathetic activity:

Neostigmine enhances ganglionic transmission

Answer 22

True. Neostigmine enhances ganglionic transmission. However, the enhancement is an unwanted effect.

Question 23

Regarding drugs clinicians use to affect parasympathetic activity:

Ipratropium is an acetylcholine analogue that stimulates post-synaptic receptors to produce bronchodilation

Answer 23

False. Ipratropium is an antagonist of acetylcholine that causes bronchodilation through inhibition of post-synaptic receptors.

Question 24

Regarding drugs clinicians use to affect parasympathetic activity:

Glycopyrronium is often used to reverse the effects of neuromuscular blocking drugs

Answer 24

False. glycopyrronium is often given to reverse/offset the unwanted effects of neostigmine. It is neostigmine that is commonly used to reverse the effects of neuromuscular blocking drugs.