14b - Autonomic NS Flashcards
Direct-acting cholinergic agonist: non-selective cholinergic (N=M) examples
- Acetylcholine
- Carbachol: more metabolically stable, don’t use systemically=danger in stopping the heart (ex. used in the eyes)
Carbachol in the eyes
- Pupillary constriction
- Aqueous humor production effected
Direct-acting cholinergic agonist: nicotinic selective (N»M) example
- Nicotine
- *mix of PS and S effects
- *muscle twitching=stimulates skeletal muscle
Direct-acting cholinergic agonist: muscarinic selective (M»N) example
- Muscarine
- Bethanechol
- Pilocarpine
- *can still affect the heart (be careful if use systemically)
- *ophthalmically OR systemically for stimulating urination
Indirect-acting IRREVERSIBLE agonist (AChE inhibitors) examples
- Organophosphate/carbamate
- Insecticides
- *non-selective cholinergic (N=M)
- *accumulation of ACh
- **double stimulation in PS (ganglion and effector organs)
o SLUD
Indirect-acting REVERSIBLE agonist (AChE inhibitors) examples
- Edrophonium
- Neostigmine
- *non-selective cholinergic (N=M)
- *used after a paralysis drug (specifically in skeletal muscle)
Cholinergic antagonists: muscarinic selective (M»N) examples
- Atropine: competitive
- Ipratropium
- *need to add A LOT of it to get a N effect
Cholinergic antagonists: Nn, ganglionic blocker (Nn>Nm»MM) examples
- Hexamethonium
- Trimethaphan
- don’t use in a conscious animal
- *controlled HYPOTENSION: stops firing of S and PS system=stops baroreceptor reflex=HR will remain low
Cholinergic antagonists: Nm, neuromuscular blocker (Nm>Nn»M) examples
- Tubocurarine
- Pancuronium
- Succinyl choline (initially an agonist, then antagonizes receptor)
o Ex. rapidly intubate and animal
*if add a lot of the drugs=will start to antagonize the next receptor
Dose effects in this course
- Assume all effects are possible
Atropine low dose: what do you see?
- Salivation: reduced
- Minor effect on inhibiting urination
- No HR increase or accommodation of vision
Atropine moderate dose: what do you see?
- Inhibits urination more
- Reduced salivation significantly
- Increased HR
- Decreased accommodation of vision
Atropine high dose: what do you see?
- Complete inhibition of salivation
- Max out HR
- Max decrease of accommodation of vision
ACh low to moderate dose IV
- No affect on activity at autonomic ganglia (nicotinic): not as highly perfused
- Decrease in diastolic BP=vasodilation (muscarinic)
- Decrease HR (muscarinic)
- Increase GI motility(muscarinic)
- *transient effects
Atropine given IV and then give ACh low to moderate dose again
- Atropine acts for many hours!
o Give it once and it persists - *muscarinic antagonists
- No change in gut motility
- Slight drop in diastolic BP (minor vasodilation)
10x dose of ACh: does atropine still antagonize?
- Yes
o Effect in gut - *autonomic ganglion=more firing (now seeing more prominent S effects)
o Increase in HR
o Increase in diastolic pressure (vasoconstriction) (atropine already reduced the vasodilation response)
Give alpha+beta blockers after atropine and then give high dose ACh: what would happen?
- Beta receptors in heart: no HR change
- Alpha receptors in arterials: no change in diastolic pressure
- NO effect in gut
- Autonomic ganglia stimulation is not effected (due to them being nicotinic)
o Would need an Nn blocker (ex. hexamethonium)