Beta-adrenoceptor blockers/antagonist Flashcards
What are adrenergic receptors?
- GPCRs - part of sympathetic system
What hormones activate adrenergic receptors?
- catecholamines - adrenaline and noradrenaline (main 2)
What are the 2 main groups of adrenergic receptors?
- alpha (a) - beta (B)
What type of transmembrane receptors are all adrenergic receptors?
- GPCRs
How many alpha adrenergic receptors are there?
- 2 - alpha 1 and 2
How many beta adrenergic receptors are there?
- 3 - B1, B2 and B3
Which GPCR do alpha receptors use to activate intracellular pathways?
- a1 = Gaq - a2 = Gai
Which GPCR do beta receptors use to activate intracellular pathways?
- all Gas
What is the basic intracellular pathway for Gaq?
- phospholipase C is activated and cleaves PiP
- IP3 and DAG are formed
- IP3 increases Ca2+
- Ca2+ binds with DAG and activates protein kinase C
- protein kinase C can phosphorylate inside cell
What is the basic intracellular pathway for Gas?
- adenlyly cyclase (AC) is activated
- AC converts ATP into cAMP
- cAMP activates protein kinase A
- protein kinase A can phosphorylate inside cell
What is the primary function of a1 adrenoreceptors receptors during fight or flight?
- vasoconstriction (primarily blood vessels)
- bladder sphincter contraction
What is the primary function of a2 adrenoreceptors receptors during fight or flight?
- inhibit release of noradrenaline
- inhibit release of acetycholine
- inhibit release of insulin
What is the primary function of B1 adrenoreceptors receptors during fight or flight?
- ⬆️ Heart rate
- ⬆️ Inotrophic contractility
- ⬆️ Renin release (fluid and salt retention)
What is the primary function of B2 adrenoreceptors receptors during fight or flight?
- Vasodilation (skeletal muscle)
- Bronchodilation
- Gluconeogenesis (⬆️ glucose from liver)
Propranolol was the first ever beta blocker invented. What beta channels does in block?
- all as it is a non selective beta blocker
- inhibits B1 and B2 adrenergic receptors