drugs acting on neuromuscular junction

Question 1

curonium

Answer 1

alkaloid extract from curare plants originating from central and south america

used for arrow poisons by local tribes

competitively and reversibly inhibiting the nicotinic receptor at the Neuromuscular junction

Question 2

succinylcholine

Answer 2

depolarizing agent

Question 3

Ach releasing inhibitor: Botox

Answer 3

botulinum toxin (botox): a protein produced by clostridium botulinum (food poisoning-deadly)

Question 4

muscle relaxants

Answer 4

used during anesthesia to allow easier intubation of the trachea, and improved operating conditions

Question 5

reversal of effects of curonium

Answer 5

neostigmine normally required by the end of operation for timely recovery.

Question 6

neostigmine

Answer 6

inhibits cholinesterase. thus increases Ach level at NMJ . thus more Ach to compete with curonium, Ach them outcompetes curonium for binding of AChR. this reverses the blocking effects of curonium. and you get the reversal of muscle relaxation.

Question 7

what is succinylcholine composed of?

Answer 7

2 molecules of acetylcholine

Question 8

what is the function of succinylcholine?

Answer 8

an agonist to AChR but resistant to AChE.

only metabolized by pseudocholinesterase.

Question 9

what is the use of succinylcholine?

Answer 9

used as a muscle relaxant for endotracheal intubation and electroconvulsive therapy.

rapid onset (30 sec) and short duration (5 mins). allow for spontaneous recovery.

Question 10

phase 1 block(persistent depolarization block) of succinylcholine

Answer 10

binding to AChR –> persistent depolarization–>transient fasciculation–> no repolarization–>no more action potential –>muscle relaxation

Question 11

phase 2 block (receptor desensitization block)

Answer 11

exposure to succinylcholine desensitize the AChR

Question 12

what are the side effects of succinylcholine?

Answer 12

bradycardia, hyperkalemia, malignant hyperthermia.

Question 13

potentiating effect of neostigmine on depolarizing muscle relaxants (succinylcholine)

Answer 13

neostigmine—>inhibits pseudocholinesterase–>succinylcholine is not broken down –>sustained (succinylcholine) at NMJ–>prolonged succinylcholine action at NMJ–>potentiation of muscle relaxation.

Question 14

mechanism of botox

Answer 14

botox cleaves SNARE PROTEINS. No SNARE complex formed so no fusion of synaptic vesicle with axon plasma membrane.–>NO ACh release into synapse

Question 15

botox cosmetic effects

Answer 15

inhibits ACh release–> TEMPORARY paralysis of muscle –>muscle relaxation–>dec wrinkles–>smoother and younger looking skin

Question 16

what are the side effects of botox?

Answer 16

droopy eyelid, crooked smile, drooling, frozen face, vision problem, and trouble speaking or swallowing.