Autonomics Flashcards
What are the 3 kinds of muscarinic receptors and where are they found?
M1, M2 and M3M1 is found in CNS and enteric nervous systemM2 is primarily in heart, decreases heart rate only at the SA nodeM3 is at the glands, bladder and smooth muscles of the eye
Explain M1 MOA.
M1 Gq - activate IP3-DAG cascade –> increased intracellular calcium;
Explain M2 MOA.
M2 is Gi, decreases cAMP
Explain M3 MOA.
M3 is Gq - activate IP3-DAG cascade –> increased intracellular calcium;
What happens in an intact endothelium when muscarinic agonist is administered
Vasodilation
What happens vasculature without endothelium when muscarinic agonist is administeredWhat disease is this phenomenon associated with?
Vasoconstriction by increasing intracellular Ca in the smooth musclesAtherosclerosis
Bethanecol
Used to treat non-obstructive gastrointestinl dysmotility (e.g. post-op ileus, neurogenic ileus - like from spinal cord injury, congenital megaocolon) and urinary retention. Muscarinic agonist increase the secretory ability and motility of the gut
Pilocarpine
Pilocarpine - increases salivation (treats fry mouth - sjograns) and treats glaucoma by contracting the ciliary muscles, facilitating the outflow of aqueous humor and causing pupillary constriction ; causes accommodation of lens
How is acute angle glaucoma treated?
For acute angle glaucoma it is important to cause contraction of sphincter papillae muscle which leads to pupillary constriction, pilocarpine can be used to achieve this
What are the 3 places where nicotinic receptors are found?
Autonomic ganglia, skeletal muscle motor end plates, and adrenal gland (post ganglionic organ)
MOA of nicotinic receptors?
transmembrane polypeptides that act as ion channels (influx of positive ions –>depolarization of skeletal muscles
What drug is used for smoking cessation
Very clean = Vernicline
Carbachol
Carbachol - both muscarinic and nicotinic agonist, causes pupillary constriction (useful in acute angle-closure glaucoma)
What are indirect cholinomimetics?
ACh esterase inhibitors
What is one disease that involves the use of indirect cholinominetics to increase ACh at the NMJ?
Myasthenia Gravis - antobodies against the ACh receptors are made
What are the different kinds of indirect cholinomimetics?
Quaternary, tertiary and phosphate derivatives. Quaternary cannot cross the BBB hence their effects are more peripheral, tertiary have more central effects
What are the examples of quaternary AChEI?
NeostigminePyridostigmineEdrophonium
What is the use of neostigmine?
Can reverse nondepolarizing neuromuscular blockade after surgery (removing effects of anesthesia); like urinary retention after surgery
What are the uses of pyridostigmine?
Long-term treatment for MG; only symptomatic treatment
What is the use of edrophonium?
Diagnosis of MG since it has a very short half life.
Describe the test that is done to dx MG?
It is called the tensilon testPt comes with worsening MG symptoms: 1. could be over treated (cholinergic crisis - too much ACh) or 2. could be undertreated (Myastenia crisis)If give edrophonium and symptoms get better, then undertreated/Myasthenia crisis
Give an example of tertiary AChEI? What are its uses?
Physostigmine, used for more of its central CNS effects since it can cross the BBB
Name two plants which are known to cause atropine poisoning.
Belladonna flower and Jimson’s weed, Jimson’s weed is also called Gardner’s mydriasis
Name drugs that are specific for nicotinic receptors at the NMJ?
Tubocurarine, Pancuronium, Cisatracurium