Trachte Adrenergic Agonists Flashcards
Relate HR, TPR, SV and BP
BP = HR x SV x TPR
Stepwise synthesis of NE:
Tyrosine –> DOPA –> Dopamine –> NE –> Epi (in adrenal medula)
Cholinergic receptors in Heart and vessels:
Which nerve acts on them?
Muscarinic (M2)
Vagus (pre-ganglionic; Ach on Nicotinic R)
Parasympathetic
Adrenergic receptors on heart and vessels:
NT and R for ganglia synapse?
Beta1 (NE)– Heart
alpha 1 (NE)– vessels
Ach, Nicotinic
Sympathetic
Cholinergic receptors on sweat glands: NT?
M2, Ach
(ganglia is Ach, Nic)
Sympathetic
Sympathetic NT and receptor of renal vessels:
Dopamine, D1
ganglia is Ach –> Nic
NT’s in the blood that act on Beta 1’s and alpha 1’s in the heart and vessels:
Where do they come from?
Epi
NE
Adrenal medula (sympathetic response via preganglionic neuron Ach on Nicotic R in the medula)
Inhibits axoplasmic pump to potentiate sympathetic response:
Cocaine
Inhibits granular pump accumulating catecholamines in vesicles (results in depletion of catecholamines):
Respirine
Induces release of NE from vesicles –> depletes NE stores –> reduces response to sympathetic stimulation
**inactive in the presence of MOA inhibitors like Pargyline
Guanethidine
Two enzymes that degrade adrenergic amines:
COMT (cytoplasm)
MAO (mitochondria)
MAO inhibitor:
Patients taking this should avoid what?
pargyline
foods high in tyramine
a1 receptor
primary CV location:
relative response to NT’s:
MOA:
blood vessels
epi >/= NE»_space; isoproterenol
activates phospholipase C (Gq protein rec.) –> inc. intracellular Ca2+ via IP3
**mediates smooth muscle CONTRACTION
Beta 1 receptor
locations:
relative response to NTs:
MOA:
adrenergic cardiac effects, renin release
heart, JG apparatus and adipose tissue
isoproterenol > epi = NE
acts to increase cAMP via Gs
Beta 2 receptor
locations:
relative response to NTs:
MOA:
relaxation of smooth muscle and glycogenolytic effects
vascular smooth muscle
isoproterenol > epinephrine»_space; NE
increase cAMP via Gs
Selective B1 agonist
positive inotrope (increases muscular cont.)
Dobutamine
- positive inotrope at B1
- vasodilator in renal and mesentary at low doses (dopaminergic)
- vasoconstrictor at a1 at high doses
used in shock (maintains renal perfusion) and hypotension (inc. BP and CO)
Dopamine
a1 agonist
used to reverse hypotension or treat paroxysmal atrial tachycardia
also used as mydriatic and topical vasoconstrictor
Phenylepherine
B2 selective agonists used for bronchodilation (3):
Metaproterenol
Albuterol
Salmeterol
B2 selective agonists used to delay labor (2):
ritodrine
terbutaline
vasodilates at B2
tachycardia at B1
metabolised by COMT but not MAO
synthetic catecholamine
Isoproterenol
Vasoconstricts at a1
increases HR and force at B1
used to treat hypotension
Norepinephrine
Vasoconstricts a1
vasodilates B2
inc. HR
used in anaphylaxis to treat bronchospasm and hypotension
Epinephrine
