Adrenergic Pharmacology Flashcards
What type of neurons are all preganglionic fibers in the autonomic nervous system?
Cholinergic
What neurotransmitters are primarily involved in the adrenergic synapse?
Noradrenaline and adrenaline
Where is noradrenaline produced within the sympathetic nervous system?
Adrenergic neurons and adrenal medulla
What enzyme is crucial in the first step to synthesis of noradrenaline and adrenaline?
Tyrosine hydroxylase
How is noradrenaline release regulated at adrenergic synapses?
By autoinhibitory feedback mediated by α2 receptors
What are the two important classes of adrenergic receptors?
α and β receptors
What effect does stimulation of α1 receptors have on blood vessels?
Vasoconstriction
How does the β1 receptor affect the heart?
Increases the rate and force of contraction
What is the role of β2 receptors in the lungs?
Relaxation of smooth muscles, leading to bronchodilation
What is the clinical use of α-methyl-p-tyrosine?
Alternative treatment for pheochromocytoma. It inhibits Tyrosine hydroxylase
How does reserpine affect noradrenaline storage?
Inhibits vesicular uptake of NA, leading to its depletion
What is the mechanism of action of indirect sympathomimetic drugs like amphetamine?
Taken up by NET and VMAT in exchange for NA reducing NA reuptake.
NA, is then metabolised by MAO or escapes via NET back into the synaptic cleft augmenting NA release.
Have an inhibitory effect on MAO
How does cocaine affect noradrenaline neurotransmission?
Inhibits the reuptake of noradrenaline at presynaptic terminal
What are the effects of sympathomimetics on the cardiovascular system?
Increased heart rate and force of contraction, leading to hypertension
How do α2 receptors regulate noradrenaline release?
Inhibit the release of noradrenaline via feedback inhibition
What role does clonidine, an α2 receptor agonist, play in blood pressure regulation?
It inhibits noradrenaline release, which can lower blood pressure
How do β1 receptors influence renal function?
They increase the release of renin from juxtaglomerular cells, which raises blood pressure
What is the effect of activating β2 receptors on vascular smooth muscle?
It leads to vasodilation
How does adrenaline act during anaphylaxis?
It decreases the release of mediators from mast cells, alleviates airway obstruction, and improves cardiovascular response
What is the result of α1-adrenergic agonist effects during anaphylaxis?
Increased vasoconstriction, increased peripheral vascular resistance, and decreased mucosal edema
What is the impact of β2-adrenergic agonist effects during anaphylaxis?
Increased bronchodilation and decreased release of inflammatory mediators from mast cells and basophils
What is the primary action of α1 receptors on blood vessels?
Vasoconstriction