Autonomics III: Cholinergic Receptor-Inhibiting Drugs

Question 1

are muscarinic antagonists selective?

Answer 1

no, they do not discriminate well between the 5 muscarinic receptor subtypes.

Question 2

emergency uses for muscarinic antagonists

Answer 2

treatment of poisoning with cholinesterase inhibitors (nerve gases and insecticides) and mushrooms. atropine is best for this. tropicamide has a short half life and deals with nicotinic effects

Question 3

toxicity of muscarinic antagonists

Answer 3

dry as a bone, blind as a bat, red as a beet, mad as a hatter. reduced sweating, lacrimation, and salivation. excessive pupil dilation. dilation of cutaneous vessels in upper body. inhibition of CNS muscarinic receptors

Question 4

atropine fever

Answer 4

blockade of thermoregulatory sweating. can lead to hyperthermia

Question 5

ganglionic blockers mechanism

Answer 5

competitively inhibit Nn receptors at both sympathetic and parasymp ganglia. lack of selectivity left them abandoned for clinical use.

Question 6

NMJ blockers mechanism

Answer 6

interfere with transmission at the axon terminals and are useful as skeletal muscle relaxants. several act by inhibiting Nm receptors. can either be nondepolarizing or depolarizing. used to facilitate surgery and ventilation

Question 7

toxic efffects of NMJ blockers

Answer 7

respiratory paralysis and disturbance of autonomic function. non-depolarizing blockers are blocked by cholinesterase inhibitors, but nothing can fix depolarizing blockers.

Question 8

botulinum toxin A

Answer 8

degrades SNAP-25, which mediates fusion of synaptic vesicles with the presynaptic terminal membrane.