Cholinergic Agonists/Antagonists

Question 1

Muscarinic receptor M1

Answer 1

Increased IP3, DAG, and Ca

Activated myenteric plexus

Question 2

Muscarinic receptor M2

Answer 2

Opens K channels
Decreases heart rate and contraction (decreased CO)

Decreased cAMP, decreased Ca
Inhibits NE release from sympathetic nerve terminals

Question 3

Muscarinic receptor M3

Answer 3

Increased IP3, DAG, and Ca
Contracts circular ciliar muscle (pupillary constriction, near-vision accomodation), bronchiolar muscle, GI smooth muscle, uterine muscle, bladder detrusor muscle (micturition)

Relaxes vascular muscle (via NO from endothelium)

Stimulates secretions of GI tract, eccrine sweat glands, tear glands, salivary glands, pancreas digestive fluids, and liver bile

Question 4

Nicotinic receptor

Answer 4

Ligand mediated ion channel

Ach binding, conformation change, Na comes is and allows depolarization of the membrane

Question 5

Open angle glaucoma

Answer 5

Fluid goes past lens and pupil, can still pass through drainage canals but there is some resistance in trabecular meshwork

Question 6

Closed-angle glaucoma

Answer 6

Trabecular meshwork angle obsured by pupil, rapid increase in pressure and pain

Emergency situation

Question 7

Cholinesterases

Answer 7

Acetylcholinesterase: NM junction and cholinergic synapses, RBCs

Butrylocholinesterase (pseudocholinesterase): plasma, glial cells, liver

Inhibition of these increase Ach at synapse, increased muscarinic and nicotinic actions

Question 8

Organophosphate toxicity

Answer 8

DUMBBELS
Diarrhea
Urination
Miosis
Bradycardia
Bronchorrea
Emesis
Lacrimation
Salivation

Question 9

Treatment of irreversible cholinesterase inhiitors

Answer 9

1. Ventilation
2. Suction of tracheal secretions
3. Anti-muscarinic agent (atropine)
4. Reactivation of acetylcholinesterase with pralidoxime chloride (2-PAM)