AUTONOMIC PHARMACOLOGY Flashcards
What type of receptors are parasympathetic receptors?
Nicotininc muscarinic receptors
What type of receptors are sympathetic receptors?
Noradrenaline receptors
Which enzymes break down acetylcholine?
Esterase enzymes
Which aspects of the nervous system do drugs target?
Junctions and synapses
Can target axons but its not specific
What is hexamethonium?
- A drug that is no longer used.
- Blocks the voltage gated sodium and calcium ion channels
- Non competitive
- Selective antagonist for neuronal sub type of nicotinic receptor
- Blocks all effects of autonomic stimulation and blocks autonomic transmission as well as enteric
- Methonium derivative
What type of receptors are found in sympathetic and parasympathetic ganglion?
Nicotinic receptors
What are muscarinic agonists called?
Parasympathomimetic drugs because they mimic the effects of parasympathetic activation
What are the effects of parasympathomimetics?
- Decreased heart rate
- Increased digestion
- smooth muscle contracts
- secretion of exocrine glands
Effects of muscarinic poisoning?
Too much muscarine agonist which overstimulates the receptors
- Bradycardia
- vasoldilation
- pupil constriction
What is the treatment for muscarine poisoning?
Atropine - an antagonist to muscarinic receptors and prevents too much muscarine from binding which can cause poisoning of the receptors
What are alpha and beta adrenergic receptors?
They are receptors that are specific to catecholamines - adrenaline and noradrenaline
Alpha = mediate smooth muscle contraction and vasoconstriction
Beta = smooth muscle relaxation and vasodilation
Describe muscarinic receptors
- They are transmembrane spanning and have 7 transmembrane segments
- Has 5 different subtypes
Describe muscarinic receptors
- They are transmembrane spanning and have 7 transmembrane segments
- Has 5 different subtypes - M1-3 are important peripherally
Where are M1, M2 and M3 receptors found?
- M1 = Stomach and salivary glands
- M2 = Cardiac
- M3 = Smooth muscle
What are the 5 subtypes of adrenergic receptors and what do they do?
a1 = contract smooth muscle (vasoconstriction)
a2 = Central inhibition of sympathetic outflow, direct vasoconstriction
b1 = Increase heart rate and contractivity
b2 = relax smooth muscle - bronchodilation and vasodilation
b3 = relax smooth muscle and stimulate lipolysis
Give two uses of a1 receptor agonists
- Vasoconstrictors with local anaesthetics (adrenaline and noradrenaline)
- Nasal decongestants (phenylephrinre)
Give two uses of an a2 receptor agonist
- Hypertension treatment - acts on central a2
- Facial erythema in rosacea (Brimonidine which causes direct vasoconstriction)
What are the two main uses of a1 receptor antagonists
- Hypertension
- Benign prostatic hyperplasia
Which neurotransmitter binds to muscarinic receptors?
Acetylcholine
Main use of b1 receptor agonists
Cardiogenic shock - adrenaline & dobutamine
Main use of b2 receptor agonists (2)
- Asthma
- Delay of premature labour
Main uses of beta receptor antagonists (5) and an example
Example: metoprolol
- Anginas, cardiac arrhythmias
- Hypertension
- Anxiety states
- Chronic heart failure
- Locally for glaucoma
How can drugs affect/ alter sympathetic transmission?
Interfere with the processes involved in the synthesis of noradrenaline, the exocytosis of NA or the termination of noradrenaline signalling
What is the main way in which noradrenaline signalling is terminated?
- Neuronal uptake by secondary active transporter NAT
- This terminates its action
- It is then repackaged into vesicles and if it isn’t needed it is broken down by the Monamine Oxidase enzyme (MAO)
