Pharmacology of the NMJ

Question 1

agents that affect nerve AP

Answer 1

• tetrodotoxin

- local anesthestics

Question 2

agents that affect vesicular Ach Release

Answer 2

• botulinum toxin

- tentanus toxin

Question 3

agents that affect depolarization

Answer 3

• curare alkaloids (d-tubocurarine)

- succyinylcholine

Question 4

agents that inhibit acetylcholinesterase

Answer 4

acetylcholinesterase inhibitors

Question 5

agents that affect muscle AP

Answer 5

tetrodotoxin

Question 6

agents that affect muscle contraction

Answer 6

dantrolene

Question 7

tetrodotoxin

Answer 7

• blocks voltage gated Na+ channels

- weakness, dizziness, paresthesias of face and extremities, loss of reflexes, some cases generalized paralysis

Question 8

local anesthetics

Answer 8

• inhibit voltage gated Na+ channels

- utilized for pain control

Question 9

botulinum toxin

Answer 9

• caused by gram+ rod shaped bacteria found on veggies, fruits, seafood
• cleaves SNARE complex- prevents release of ACh
• onset= bilateral cranial neuropathies
• blurred vision, nausea, vomiting, abdominal pain, diarrhea, dry mouth
• used clinically: dystonia, lines and wrinkles of face, hyperhidrosis, migraine headaches

Question 10

tetanus toxin

Answer 10

• blocks fusion of synaptic vesicles by targeting synaptobrevin
• transported to spinal cord
• spastic paralysis, lockjaw, sweating, tachycardia, stiff neck, board like abdomen, opisthotonus, dysphagia

Question 11

curare alkaloids (d-tubocurarine)

Answer 11

• competes with ACh for nAChR- antagonist
• flaccid paralysis of skeletal muscle
• used during anesthesia
• reversed by using acetylcholine esterase inhibitor

Question 12

succinylcholine

Answer 12

• binds skeletal muscle nAChRs
• acts as agonist
• causes continued depolarizaiton
• induction agent for anesthesia
• causes transiet muscle fasciculations
• paralysis reversed by tie

Question 13

acetylcholinesterase inhibitor

Answer 13

• inhibits hydrolysis of ACh
• used in treatment of dementia, myasthenia gravis (decreased nAChRs), reversal of neuromusclar blockage during anesthesia, treatment of urinary retention
• also used as insecticide poison

Question 14

Dantrolene

Answer 14

• inhibits ryanodine receptors in SR
• blocks release of Ca2+
• treatment of malignant hyperthermia (occurs after exposure to succinylcholine), and spasticity associated with upper motor neuron disorders