Autonomic Pharmacology 2
Terms
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- Sympathetic Nervous System
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Widespread Activation
One preganlionic neuron innervates many postganglionic neurons
=Chromaffin cells secrete epinepherine and norepinepherine - Parasympathetic NS
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Discrete Activation
One preganglionic neuron innervates one postganglionic neuron.
-No large-scale release of hormone into the blood. - Sympathetic Effect on Organs and Vessels
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Heart->increased CO
Lungs->Inreased o2 delivery
Liver->Increased glucose production
Adrenal Medulla->Release of epi & norepi
Sweat Glands->Increased sweating
Vascular Smooth Muscle->Vasodilation of arteries and vasoconstriction of unimportant vessels - Parasympathetic Effects on Organs and Vessels
- Increased salivation, decreased CO, contraction of bronchiole smooth muscle, Increased GI motility, urination
- Parasympathetic NT
- Postganglionic release Acetylcholin-->muscarinic receptors
- Sympathetic NT
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Postganglionic release Epi & Norepi-->Adrenergic Receptors (A&B)
EXCEPT SWEAT GLANDS->acetylcholine=muscarinic and RENAL VASCULAR SMOOTH MUSCLE=dopamine(D1 receptors) - Autonomic Drugs
- Mimics or prevents the effects of sympathetic and parasympathetic nervous systems by activating or blocking ADRENERGIC AND MUSCARINIC RECEPTORS
- Site of action for Sympathetic & Parasympathetic Drugs
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Sympathetic=Adrenergice Receptors
Parasympathetic=Muscarinic Cholinergic Receptors - Direct vs. Indirect Autonomic Drugs
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Direct=directly interact with receptors (agonists/antagonists)
Indirect=alter NT concentrations at target sites - Sites of action for sympathomimetic druges
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Reuptake blockers (Cocaine)
MAO Inhibitors (Phenelzine)
Releasing Agents (Amphetamines)
Adrenegic Receptor Agonist - Sites of action for Sympatholytic Drugs
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Synthesis InhibitorsRelease Inhibitors (Reserpine)
Autoreceptor Agonists
Adrenergic Receptor Antagonists - Examples of sympathomimetic drugs
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Cocaine-inhibits reuptake of NE
Phenylzine-inhibits MAO
PPA-releasing agent
Amphetamines-releasing agents
Ephedrine-releasing agent & direct adrenergic receptor agonist
ALL CAN CAUSE MASSIVE CARDIAC EFFECTS
(PPA USED TO BE IN COLD MEDICINE - NOW BANNED BY FDA - Sympathetic Receptors
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A1-prostate gland, vascular smooth muscle (most vessels)
A2-inhibit sympathetic ns in brain
B1-heart
B2-lungs, liver, vascular smooth muscle(arteries) - A1 Adrenergic Receptor Agonists
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Effect: Vasoconstriction
Clinical Uses: Reduce redness of eyes, reduce nasal secretions, vasoconstrictors
Side Effects: Hypertension - A1 Adrenergic Receptor Antagonists
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Effects: Vasodilation
Clinical Uses: Tx of Hypertension, Benign Prostate Hyperplasia (BPH)
Side Effects: Orthostatic Hypotension, Sweating/Flushing - A2 Adrenergic Receptor Agonists
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Effect: Reduced release of NE from sympathetic nerves
Clinical Use: Hypertension
Side Effects: Overall reduction in sympathetic activity - A2 Adrenergic Receptor Antagonists
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Effect: Increased release of NE from sympathetic nerves
Clinical Uses: None
Side Effects: Overall increase in sympathetic activity - B1 Adrenergic Receptor Agonists
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Heart
Effect: Increased force of contraction, Increased HR, Increased impulse conduction through AV node
Clinical Uses: Acute Heart Failre
Side Effects: Hypertension, Risk or Heart attack, cardiac arrhythmias - B1 Adrenergic Receptor Anatgonists
- Effects: Decreased force of contraction, decreased HR, decreased impulse conduction though AV node
- B2 Adrenergic Receptor Agonist
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Effects: Glucose metabolization, relaxation of bronchial smooth muscle, relaxation of some arterial smooth muscle
Clinical Uses: Treatment of Asthma
Side Effects: Increase blood glucose, some hypotension - B2 Adrenergic Receptor Antagonists
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Effects: Reduced glucose mobilization, contraction of bronchial smooth muscle, contraction of some arterial smooth muscle
Clinical Uses: None
Side Effects: Impaired glucose mobilization, Bronchoconstriction (Asthma Attack) - Epinepherine Receptor Targets
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A1, B1 & B2
Little change in BP - Noriepinepherine Receptor Targets
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A1 & B1
Large increase in BP - Non-selective Beta Blockers
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Block both B1 and B2 adrenergic receptors
Effects: Decreases CO, Bronchioconstriction-->possible astham attack, impairs glucose mobilization-->impairs recovery from hypoglycemia - Cardioselective Beta Blockers
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Selectively block B1 adrenergic receptors
Effects: Reduces CO without producing effects in the lungs or liver - Clinical Uses for muscarinic agonists
- Tx of non-obstructive GI hypomotility, Tx of xerostomia, prevent urinary retention
- Clinical Uses for Muscarinic Antagonists
- Treatment of occasional diarrhea, reduce salivation during dental work, chronic obstructive pulmonary disease, overactive bladder, motion sickness
- Toxic Effects of Anti-muscarinic drugs
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Dry as a bone - xerostomia
Blind as a bat - mydriasis (visual difficulty)
Red as a beat - hyperthermia (flushing)
Mad as a hatter - agitation, hallucination
POTENTIALLY LETAL HYPERTHERMIA IN KIDS -
Anticholinesterases
(Acetylcholinesterases Inhibitors) -
Prevent acetylcholine metabolism
1) Reversible: forms a hydrolyzable chemical bond-->effects are short-lasting and mild
2) Irreversible: effects are long-lasting and severe