Adrenergic Receptors Flashcards
α1 means of action
Primarily coupled to PLC with increase in IP3 and DAG
- release K+ liver
Which G protein is coupled to α1 receptors?
Gq
What are the effects of α1 stimulation?
- Vasoconstriction (in smooth muscle)
- Medriasis in pupil
- Bowel continence, urinary retention
- Glycogenolysis in liver
- Kidney inhibits renin release
=> sympathetic response
α2 means of action
Acts on pre-sympathetic nerve endings. Decreases intracellular cAMP which decreases NA -> - feedback control
(Negatively coupled to adenylate cyclase)
Which G protein is coupled to α2 receptors?
Gi
What are the effects of α2 stimulation?
Pancreatic islets decrease insulin production
How did Alqhuist classify adrenoreceptors?
by comparing relative potencies of 5 catecholamines
Which receptor is innervated and excitatory?
β1
Which receptor is not innervated and inhibitory?
β2
What are the effects of β1 stimulation?
- Heart rate increases
2. Increased renin release
What are the effects of β2 stimulation?
- Bronchodilation
- Vasodilation of smooth muscle
- Smooth muscle relaxation -> decrease in G.I. motility
- Increase of insulin production -> mediates glycogenesis in liver and glycogen breakdown to lactic acid in skeletal muscle (hyper acidaemia) + K+
What are the effects of β3 stimulation?
- Increased lipolysis
2. Relaxed bladder
Which G protein is coupled to β receptors?
Gs
The adrenal gland releases ___% Adrenaline and ___% Noradrenaline
80, 20
β receptor general mechanism of action
Activation leads to increase in cAMP + protein phosphorylation via PKA
