Cholinergic Receptors and Agents Acting at the Neuromuscular Junction

Question 1

Where is the site of action of vesamicol?

Answer 1

Storage; Vesamicol blocks Ach transport into their vesicles blocking their storage

Question 2

Where is the site of action of Mg²⁺?

Answer 2

Release; Mg²⁺ competes with Ca²⁺ and does not allow the vesicle to release its Ach

Question 3

Where is the site of action of b-bungarotoxin?

Answer 3

Release; b-bungarotoxin blocks pre-synaptic release of neurotransmitters.

Question 4

Where is the site of action of rivastigmine?

Answer 4

Degradation; Revastigmine is a cholinesterase inhibitor that inhibits both butyrlcholinesterase and acetylcholinesterase.

Question 5

Where is the site of action of atracurium?

Answer 5

Receptor; Atracurium antagonizes the action of Ach by binding competitively with cholinergic receptor sites on motor end-plates.

Question 6

Where is the site of action of trimetaphan?

Answer 6

Receptor; Trimetaphan is a ganglionic block agent by competing with Ach for post-synaptic receptor sites.

Question 7

Where is the site of action of edrophonium?

Answer 7

Degradation; Edrophonium prolongs the action of Ach by inhibiting the action of acetylcholinesterase.

Question 8

What kind of receptors does acetylcholine activates?

Answer 8

Ionotropic and Metabotropic Receptors

Question 9

Where is the site of action of a-bungarotoxin?

Answer 9

Receptor; a-bungarotoxin blocks post-synaptic neuromuscular nicotinic receptor.

Question 10

Where is the site of action of pyridostigmine?

Answer 10

Degradation; Pyridostigmine is an acetylcholinesterase inhibitor.

Question 11

Where is the site of action of bethanechol?

Answer 11

Receptor; Bethanechol is a direct acting agonist of muscarinic receptor promoting micturition.

Question 12

Which drug is a centrally acting cholinesterase inhibitor used in the treatment of Alzheimer’s type of dementia?

Answer 12

Rivastigmine

Question 13

What is the rate limiting step in the synthesis of acetylcholine?

Answer 13

Active transport of choline into the cell

Question 14

A patient is rushed to the emergency room after ingesting an unkown substance. On examination, the patient was restlesss, had mitotic pupils, excessive salivation and lacrimation and wheezes were noted on auscultation of the lungs. Which most likely was the ingested drug?

Answer 14

Organophosphates

Question 15

True or false, pralidoxime splits the phosphorylated covalent bond if given early in organophosphate poisoning?

Answer 15

True

Question 16

True or false, large doses of cholinesterase inhibitors have no effect on the autonomic ganglia?

Answer 16

False

Question 17

True or false, depolarizing and non-depolarizing drugs have a structural resemblance to acetylecholine?

Answer 17

True

Question 18

True or false, non-deplozarizing drugs have no effect on the autonomic ganglia?

Answer 18

False

Question 19

True or false, tetanic stimulation relieves neuromuscular blockade in phase I depolarizing block?

Answer 19

False

Question 20

A patient who has renal insufficiency is ti undergo surgery for removal of renal cyst. Which neurotransmitter blocker is safest to use?

Answer 20

Atracurium

Question 21

Which drug acting on the autonomic ganglia is used to clinically treat hypertension?

Answer 21

Trimetaphan

Question 22

Which drug is responsible for block the transport of acetylcholine and forms a false neurotransmitter?

Answer 22

Triethylcholine

Question 23

Atropine causes?

Answer 23

Cycloplegia, Dry Mouth and Mydriasis

Question 24

Where is the site of action of ecothiopate?

Answer 24

Degradation; Ecothiopate is an anti-cholinesterase inhibitor.