Autonomic Drugs Flashcards
How are anti-cholinesterase agents classified?
based on duration of enzyme inhibition; related to the speed with which inhibitor dissociates from the esteric site of AChE
What receptors does norepinephrine not interact with in the ANS?
Beta 2
Cholinergic stimulation causes smooth muscle to _________
Contract
Five clinical signs you expect to see when using anti-cholinesterase agents
- Constriction of pupils
- Increased secretion of sweat, saliva, tears
- Slow heart rate
- Mucus secretion in the resp tract
- Constriction of bronchioles
Stronger beta2 agonist:
isoproterenol, epinephrine, or norepinephrine?
Iso > Epi >>Norepi
What happens if you activate Gi in a smooth muscle cell?
Contraction
mAChR activation promotes/inhibits urination?
promotes
- contracts detrusor mm
- relaxes sphincter mm
- increases peristalsis in ureters
What enzyme breaks down ACh in the synaptic cleft?
acetylcholinesterase
mAChR activation has what two effects on the eye?
- contraction of sphincter muscle > miosis (pupil constriction)
- contraction of ciliary muscle > incr curvature of lens
If you use a cholinergic agonist with high muscarinic receptor activity, what effect do you need to be concerned about on the heart?
Bradycardia
Stronger alpha1 agonist:
isoproterenol, epinephrine, or norepinephrine?
Norepi > Epi >> Iso
Descrbie muscarinic receptors
- stimulated by natural alkaloid - muscarine
- 5 subtypes
- tx drugs exhibit little/no subtype selectivity
What is the MOI of organophosphates, such as sarin?
Anticholinesterase
What type of GI tract disorder would anticholinergic drugs be used to treat?
GI spasms; these are called “spasmolytics” or “antispasmotics”
Stronger alpha2 agonist:
isoproterenol, epinephrine, or norepinephrine?
Epi = Norepi >> Iso
M1, M2 and M3 receptors couple with what G-protein?
Gq
Why do anticholinergic drugs disrupt sweating?
Because sympathetic neurons use acetylcholine for sweat gland neurons
What happens if you activate Gi in a cardiac muscle cell?
Decreased contraction
5 Therapeutic Uses for Anti-Cholinergic Agents
- Reduce smooth muscle spasms
- Antisecretory effects
- Ophthalmic exams
- Prevent heart block
- Antidotes
What does SLUD/BLUD stand for?
Salivation/Bradycardia
Lacrimation
Urination
Defecation
Nictonic receptors
- stimulated by natural plant alkaloid nicotine
- some subtypes undergo rapid desensitization with over-stimulation - tachyphylaxis
- tx drugs exhibit selectivity for nicotinic receptors in sk mm (muscle relaxants) vs. receptors in neural tissues
Stronger beta1 agonist:
isoproterenol, epinephrine, or norepinephrine?
Iso > Epi = Norepi
Explain the effects of mAChR activation on blood vessels
- agonists cause pronounced atypical relaxation of vascular smooth muscle and fall in blood pressure
- mAChR are located on endothelial cells
- mediated by nitric oxide
What receptors does isoproterenol not interact with in the ANS?
alpha 1 and 2
M2 and M4 receptors are coupled with what G-protein receptor?
Gi
Does mAChR activation causes bronchial smooth muscle contraction or dilation?
Contraction > bronchoconstriction
mAChR activation promotes/inhibits secretions from most secretory glands?
Promotes (SLUD)
Key differences between glycopyrrolate and atropine
- less CNS effects (sedation, amnesia, etc.)
- longer half life & more potent
- less tachycardia
Major effects of ACh on the GI tract
- incr motility & peristalsis
- incr smooth muscle tone
- incr amplitude of contractions
- incr secretions (acid)
What type of GI disorder would cholinergic agonists be used to treat?
constipation/impactions; these are “prokinetic agents”
What happens if you activate Gq in a smooth muscle cell?
Contraction
Signs of acute organophosphate poisoning
- inhaled: ocular, respiratory
- oral: GI, systemic signs
- cutaneous: sweating, muscle fasciculations
What is acetylcholine important for in the CNS?
cognition
What are the parasympathetic effects on cardiac tissue mediated by?
the vagal release of ACh> activates cardiac mAChR > baroreceptor reflex > reduction in heart rate
Describe a typical parasympathetic pre- and post-ganglionic neuron
Two synapses; long pre-ganglionic axon, short post-ganglionic axon
What is the function of the parasympathetic nervous system?
provides “vegetative” or resting control of visceral organs; excessive activity causes SLUD/BLUD syndrome
What happens if you activate a nicotinic receptor on a neuron, smooth muscle, or cardiac muscle cell?
- You will increase cell activity, and thus increase probability of neurotransmitter release, as well as cause smooth muscle contraction and cardiac muscle contraction.
- increased alertness (neurons), heart rate (cardiac muscles), and blood pressure (smooth muscle)
