Metabolism of Noradrenaline Quiz & Flashcards

What is the primary mechanism for termination of noradrenaline (NA) at the nerve terminal?

Which of the following drugs inhibits the Uptake 1 mechanism for termination of NA?

What is the enzyme responsible for the conversion of dopamine to noradrenaline in the cytoplasm?

Which of the following drugs inhibits the storage of noradrenaline in vesicles?

What is the mechanism of action of guanethidine, a sympatholytic drug?

Which of the following accurately describes the actions of alpha-1 (α1) receptors?

Which receptor type is associated with the inhibition of noradrenaline release and insulin release from the pancreas?

Which receptor type is associated with chronotropic, inotropic, and dromotropic effects on the heart, as well as renin release from the kidney and lipolysis in fat cells?

Which of the following actions is NOT associated with beta-2 (β2) receptors?

Which receptor type is associated with the relaxation of the detrusor muscle of the bladder wall, leading to urinary retention, as well as glycogenolysis and gluconeogenesis in the liver?

Which of the following accurately describes the actions associated with the Gs receptor type?

Termination of Noradrenaline (NA)

Primary mechanism is the reuptake of NA into the nerve terminal, known as Uptake 1.
This process decreases NA concentration in synaptic cleft, ending its action.

Drugs and Uptake Inhibition

Some drugs inhibit the Uptake 1 mechanism, leading to increased levels of noradrenaline in synaptic cleft.

Conversion of Dopamine to Noradrenaline

Enzyme responsible for this conversion in the cytoplasm is dopamine β-hydroxylase.

Inhibition of Noradrenaline Storage

Certain drugs target the storage of noradrenaline in presynaptic vesicles, disrupting its availability for release.

Guanethidine Action

Guanethidine acts as a sympatholytic drug, blocking the release of noradrenaline from sympathetic neurons.

Actions of Alpha-1 (α1) Receptors

Alpha-1 receptors mediate vasoconstriction, increase peripheral resistance, and stimulate glycogenolysis.

Inhibition of Noradrenaline and Insulin Release

Alpha-2 (α2) receptors are responsible for inhibiting both noradrenaline release and insulin secretion from the pancreas.

Beta-1 and Beta-2 Receptor Effects

Beta-1 (β1) receptors are linked with increasing heart rate (chronotropic), myocardial contractility (inotropic), and conduction velocity (dromotropic), alongside stimulating renin release and promoting lipolysis.

Actions NOT Associated with Beta-2 (β2) Receptors

Certain effects, like increased contraction of smooth muscle, are NOT associated with β2 receptor activation.

Detrusor Muscle Relaxation and Glycogenolysis

Beta-3 (β3) receptors are linked with relaxation of the detrusor muscle in the bladder, promoting urinary retention, as well as facilitating glycogenolysis and gluconeogenesis in the liver.

Gs Receptor Type Actions

Gs receptor type is involved in stimulating adenylyl cyclase, increasing cyclic AMP (cAMP) levels, and enhancing protein kinase A (PKA) activity, leading to various cellular responses.

Test your knowledge on the synthesis and metabolism of noradrenaline with Assoc. Prof. Dr. Dayang Fredalina Basri. Explore topics such as the site of Noradrenaline synthesis in the brain, storage mechanisms, and the steps involved in Dopamine-β-hydroxylase pathway.