Flashcards in Lecture 11/12 - Cholinergic Agonists Deck (79):
What are the direct acting cholinergic agonists? (six)
What are the cholinesterase inhibitors? (six)
What abnormality inhibits ACh release?
What can prolong the effects of ACh?
What does ACh stimulate?
M + N
Where are muscarinic receptors located?
PNS effector organs
What is M1+3 linked to?
What is M2 linked to?
Where are muscarinic receptors where the PNS is not?
What do nicotinic receptors respond to?
ACh + Nicotine
What is a special characteristic of nicotinic recptors?
Where are nicotinic receptors found?
Why can drugs select between NMJ and autonomic nicotinic receptors?
Both have different structures
What is direct action?
Agonist binds and stimulates receptor
What is indirect action?
Molecule binds to enzyme or other part of pathway that leads to a different effect of NT
What will happen with ACh injection/
Slowing of HR - M2
Drop in BP - M3
Why can't you give ACh orally?
Charged, not absorbed
What does bethanechol stimulate?
M receptors only
What effects predominate with bethanechol?
Bladder + GI
Does bethanechol enter the brain? Why?
What does pilocarpine stimulate?
M receptors only
What are the distribution characteristics of pilocarpine?
Not charged, so taken orally
Gets into CNS
What is pilocarpine used for in the eye?
Decrease intraocular pressure (M3)
What is really sensitive to pilocarpine that leads to side effects? what are the effects?
Sweat + Salivary glands
What does muscarinic stimulation do to the heart?
Vagal stimulation = Bradycardia (M2)
Conduction slowed through AV node
Pre-synaptic decrease NE = Decrease HR (M2)
What does muscarinic stimulation do to the blood vessels?
NO PNS, but M3 is present on endothelium
ACh given IV will cause vasodilation
How does ACh given IV cause vasodilation?
What happens with release of NO from endothelial cells?
cGMP production + Vasodilation
What is the PNS tone like in the GI tract?
High, responsible for digestion
What are the effects of muscarine on the GI tract?
Motility + Peristalsis increase
Salivary + Gastric secretions increase
How is carbachol used with horses?
Treatment of colic or impactions
What do you have to watch out for when using carbachol in horses?
If obstruction is present can lead to intestinal rupture
What is carbachol used for in cattle?
Rumen atony and impaction
What does normal PNS activity do to the bladder?
Enhances overall activity
What do muscarinic drugs do to the bladder?
Bladder tone + peristalsis increase
Void pressure increase
Bladder capacity decrease
Trigone and sphincter relax
What is the basic end result of muscarinic stimulation of the bladder?
What drug is used for bladder effects?
What is betahanechol used for?
Urinary atony in cats following urolithiasis
What do you have to watch out for when using betanechol in cats?
That the urethra is patent, so they can control urine output
What are the muscarinic effects in the eye?
Circular muscle contraction = Pupil smaller
Increased AH drainage = Decreased pressure
Ciliary muscle contracts = Near vision
How is pilocarpine used in the eye?
KCS + Glaucoma
What are the side effects of pilocarpine in the eye?
Blurred vision + Brow ache
What are the muscarinic side effects?
Nausea + V/D + Colic
Bladder tightness = Increased urination
Bronchoconstriction + increased mucus
What happens with muscarine toxicity?
Same as side effects just worse
Hypotension + Shock + Bradycardia
What is muscarine toxicity treated with?
Atropine + Albuterol
What are the three main places for nicotinic receptors?
What type of channel is nicotinic receptors?
Ligand gated Na+ channel
What movement of ions occurs with an activated nicotinic receptor?
Na/Ca = in
K = out
What, in the most general sense, does N activate?
SNS + PNS
What are the SNS effects with nicotinic stimulation?
Tachycardia w/ vagal bradycardia
What are the PNS effects with nicotinic stimulation?
Nausea + Vomiting + Diarrhea + Urination
What happens with desensitization of the NMJ?
Initial muscle twitch/contraction + depolarization blockcade
What is seen with nicotine toxicity?
Convulsion + coma + respiratory arrest
Skeletal muscle depolarization
Hypertension + Cardiac arrythmia
What three things are done to treat nicotine toxicity?
Atropine + Anticonvulsants + Assist respiration
What are the four major drugs that affect AChE? (not toxins)
What are the five examples of Organophostphates?
DFP + Eschothiophate + Soman + Sarin + Malathion
What are the distribution characteristics of neostigmine?
Charged, cant be taken orally + no CNS N
Acts mostly on skeletal muscle
How does pyrdiostigmine compare to neostigmine?
What are the general characteristics of Physostigmine?
U-shaped response curve
What is Physostigmine used for?
What is the duration of action for Edrophonium?
Very short = 5 to 10 min
What is edrophonium used for?
Diagnosis of myasthenia-like syndrome
What is used to treat myasthenia-like syndrome?
What is the problem with organophosphates?
Due to aging, becomes irreversible
What can stop oragnophosphate aging?
2-PAM, if given 3 to 4 hours post-exposure
How does aging occur?
Phosphorus-Oxygen bonds breaks
Bond to AChE irreversible
Why does 2-PAM stop the "aging" process"?
Attracts organophosphate away from AChE
What is important to remember when using 2-PAM?
If organophosphate not present it can inhibit AChE itseld
What are the CNS effects of AChE inhibition?
Convulsions + respiratory arrest
What are the effects of AChE inhibition on the eye?
What are the effects of AChE inhibition on GI/bladder?
V/D + Abdominal cramps + Urination
What are the effects of AChE inhibition on the respiratory system?
Salivation + Secretion + Bronchoconstriction
What are the cardiovascular effects of AChE inhibition?
Prolonged ACh = M2 stimulation
Bradycardia + Decrease contraction + Decrease CO
What happens with low concentrations of AChE inhibitors at the NMJ?
Skeletal muscle strength increases
What happens with high concentrations of AChE inhibitors at the NMJ?
Twitches + Fasiculation
What is myasthenia gravis?
Ab's to nicotinic receptors
Not enough ACh to stimulate
Weakness and fatigue with excercise
What is physostigmine used for?
Eye = miosis + decrease pressure
Synechia = alternate with atropine
Rumen atony = in cattle
What are the side effects of AChE inhibitor toxicity?
Salivation + Lacrimation + Urination + Defecation + Gastric distress + Emesis