Autonomic NS 3 Flashcards
Give examples of catecholamines.
Adrenaline, Dopamine, Noradrenaline
How may Tyrosine hydroxylase be inhibited ?
By catecholamines (hence negative feedback)
How may DOPA decarboxylase be targeted ?
Using Methyldopa
Where is Dopamine beta-hydroxylase enzyme located ?
Membrane bound
Where PMNT located ? How is its release induced ?
Describe the process of Noradrenaline release.
Release facilitated by Ca2+ (hence ↓Ca2+ influx means ↓NA release)
Is there an equivalent of anticholinesterases for NA ?
No
What process occurs if excessive NA if release in the synapse ?
Binds to α2 adrenoreceptors on pre-synaptic terminal, which goes on to inhibit Calcium intake, thereby reducing NA release
What molecules, besides NA, do vesicles contain during NA release ?
ATP (has its own receptors on post-synaptic terminal)
How much of the NA is recaptured by neurons ?
75%
Which molecules are responsible for NA re-uptake and re-packaging ?
What are some drugs which can affect noradrenergic neurons ? Give examples for each.
DRUGS AFFECTING CATECHOLAMINE SYNTHESIS
– e.g. methyldopa
DRUGS AFFECTING CATECHOLAMINE RELEASE
– Indirectly acting sympathomimetics (e.g. amphetamines)
– By acting on α2 adrenoreceptors (e.g. clonidine)
INHIBITORS OF CATECHOLAMINE UPTAKE
– NET inhibitors (e.g. cocaine, tricylic antidepressants)
INHIBITORS OF CATECHOLAMINE METABOLIC DEGRADATION
– Monoamine oxidase inhibitors used in depression
Which kind of receptors are Adrenergic receptors ?
Metabotropic (G-protein coupled receptors)
What are the main groups of adrenoreceptors ?
Are there exploitable differences in the selectivity of these receptors (α1, α2, β1, β2, β3) for catecholamines ? Which ones ?
Yes, differences in tissue distribution that allow for some specificty of drug action