Pharmacology of the ANS Flashcards
Receptors used by Parasympathetic post-ganglionic neurons
Acetylcholine and muscarinic receptors on target organs
receptors used by Sympathetic post-ganglionic neurons
Noradrenaline adrenoreceptors
Sweat glands - acetylcholine and muscarinic receptors
Kidney - dopamine and dopamine receptors
Where will you find non-adrenergic non-cholinergic receptors?
What do they use?
Gastrointestinal and reproductive tracts
Nitric oxide Vasoactive intestinal peptide Neuropetide Y 5-hydroxytryptamine ATP
What do Parasympathomimetics drugs do?
Parasympathetic agonists
Produce similar response to acetylcholine
Can activate the muscarinic receptors
Or prevents normal ACh breakdown
which drug actiavtes Nicotonic receptor
alkaloid nicotine
Which drugs activates Muscarinic receptors
alkaloid muscarine
What us the structure of Nicotinic receptors?
- Pentameric sodium ion channel
2. 2 alpha subunits -3 beta subunits
What determines the subtype of Nicotinic receptors? Hive examples
The alpha subunits
Alpha 1 = neuromuscular junction
Alpha 3 = autonomic ganglia
Alpha 4 and 7 = CNS
List the Nicotinic agonists an where they act?
- Acteylcholine, carbachol
Work at both nicotinic and muscarinic - Nicotine
Selective for ganglionic and CNS (smoking) - Suxamethonium
selective for neuromuscular junction
What is the function of the drug Carbachol?
Used to treat glaucoma
Causes pupil constriction increased aqueous humour outflow
what are the Nicotinic antagonists
- Hexamethonium
Selective for ganglionic nicotinic receptors
antihypertensive treatment - Pancuronium
Selective for neuromuscular junction receptors
Used in lethal injections - Tubocurarine
Causes skeletal muscle relaxation / paralysis
Location of Muscarinic receptors
Located on effector tissue innervated by postganglionic parasympathetic axons
What are the subunits Muscarinic receptors and there function?
5 receptor subtypes- M1 = excitatory- location CNS M2 = inhibitory-location- heart M3 = excitatory- Smooth muscle, vascular endothelium M4 and M5 in CNS
What are the Muscarinic agonists
Acetylcholine, carbachol-
Work at both nicotinic and muscarinic
Bethanechol-
Selective for muscarinic receptors
Not hydrolysed by cholinesterase so has long duration of action
Increases bladder and gastrointestinal contraction
Pilocarpine
Selective for muscarinic receptors
Eye drops for glaucoma
What are the Muscarinic antagonists? What are there functions?
Non-selective for which muscarinic receptor Atropine- Reduced bronchial secretions Pupil dilation Treats bradycardia Used in organophosphate poisoning
Scopolamine-
GI Antispasmodic
Motion sickness
Ipratropium-
Inhaled for asthma (bronchodilator)
Muscarinic antagonists which are which are selective for specific
Pirenzepine / Telenzepine-
M1 selective antagonist
Reduces gastric acid secretions
Gallamine-
M2 selective antagonist
Causes tachycardia
Darifenacin / Solifenacin-
M3 selective antagonist
Urinary incontinence - urge
Overactive bladder
Function of Cholinesterase inhibitors
Stimulate GI function -
Cognitive enhancers
Increase skeletal muscle activity
Production and Function of Botulinium toxin (Botox)
Produced by Clostridium botulinum bacteria
Function:
Prevents acetylcholine release
Excessive sweating
Overactive bladder
What are Sympathomimetics?
Agents that produce a similar response as noradrenaline and adrenaline on the sympathetic nervous system
Give examples of Sympathomimetics drugs?
Monoamine-
Noradrenaline, adrenaline, dopamine, histamine, 5-hydroxytryptamine, melatonin
Amine group connected to an aromatic ring
Catecholamine- Noradrenaline, adrenaline, dopamine isoprenaline Catechol group (benzene + 2 hydroxyl) and amine side chain
What is Noradrenaline synthesised from?
Amino acid – tyrosine
L-DOPA
Dopamine
Noradrenaline
What degrades Noradrenaline?
Monoamine oxidase-
Catechol-O-methyltransferase (COMT)
Function of alpha and beta Adrenoreceptors-
Alpha- smooth muscle contraction
reduce cAMP-
Beta- Heart muscle contraction, smooth muscle relaxation
What are Alpha receptor agonists
-α1 phenylephrine
Vasoconstriction, nasal decongestant
-α2 clonidine
Antihypertensive (inhibits noradrenaline release)
Analgesic and sedation used in combination with ketamine
what are Alpha receptor antagonists
-α1 prazosin, doxazosin, tramsulosin
Anti-hypertensive
Benign prostatic hyperplasia
-α2 yohimbine
What are Beta receptors agonists
β1 dobutamine
Increase cardiac contractility and heart rate used in cardiac arrest and shock
β2 salbutamol
Bronchodilation for asthma
β3 solabegron
Being developed for overactive bladder and IBS
what are Beta receptors antagonists
-Non selective
Propranolol
Timolol used to decrease aqueous humour production
-β1 atenolol
Decreases heart rate and force of contractility used in angina, hypertension, cardiac dysrhythmias, tremor
-β2 butoxamine
Has no medical use
