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
α1 agonists
NA, AD, Phenylephrine, a-methyl
β receptor’s in the heart are
excitatory
α2 agonists
NA, AD, clonidine, a-methyl
β1 agonists
AD, IsoP, NA, Salbutamol
β2 agonists
AD, IsoP, Salbutamol
α1 antagonists
Phentolamine, Phenoxybenzamine, Prazosin
α2 antagonists
Phentolamine, Phenoxybenzamine, Prazosin
β1 antagonists
Propranolol, Atenolol
β2 antagonists
Propranolol, Atenolol
What are the unwanted effects of β2 antagonists?
Tremor, hypokalaemia, vasodilation
