Adrenoceptor agonists and Sympathomimetics Flashcards
Activation of sympathetic system leads to…
epinephrine release from the adrenal medulla
What is the primary neurotransmitter of the Sympathetic nervous system(SNS)?
Norepinephrine at postsynaptic sympathetic synapses
Tissues acted on by alpha one receptors and the effects at those tissues…
- vascular smooth muscle – contraction
- genitourinary smooth muscle – contraction
- intestinal smooth muscle – relaxation
- heart – Inc. in inotropy and excitability
- liver – glycogenolysis and gluconeogenesis
Tissues acted on by alpha 2 receptors and the effects at those tissues…
- Pancreatic Beta cells – dec. insulin secretion
- Platelets – aggregation
- nerve – dec. norepinephrine release
- vascular smooth muscle – contraction
Tissues acted on by beta-1 receptors and the effects at those tissues…
- heart – inc. chronotropy and inotropy;
inc. AV node conduction velocity - renal juxtaglomerular cells – inc. renin secretion
tissues acted on by beta-2 receptors and the effects on those tissues…
- smooth muscle – relaxation
- liver – glycogenolysis and gluconeogenesis
- skeletal muscle – glycogenolysis and K+ uptake
tissues acted on by beta-3 receptors and the effects on those tissues…
Adipose – lipolysis
What is the mode of action of a direct sympathomimetic?
directly binds to and activates adrenoceptors on target tissues
What is the mode of action of indirect sympathomimetic agonists?
enhance the activity of endogenous catecholamines
What 2 ways do indirect sympathomimetic agonists enhance activity of endogenous catecholamines?
- by displacing endogenous catecholamines from presynaptic nerve terminals
- by decreasing clearance of synaptic catecholamines
Which adrenergic receptor increases PVR as well as increasing CO due to increased VR?
alpha-1
Which adrenergic receptor causes contraction of pupillary dilator muscle?
alpha-1
Which adrenergic receptor erects hair via pilomotor smooth muscle?
alpha-1
Which adrenergic receptor causes contraction of the prostate?
alpha-1
Which adrenergic receptor increases force of contraction in the heart indirectly due to increased venous return (VR)?
alpha-1
Which adrenergic receptor inhibits transmitter release in adrenergic and cholinergic nerve terminals?
alpha-2
Which adrenergic receptors causes inhibition of lipolysis in fat cells?
alpha-2 (B3 stimulates lipolysis)
Administration of a pure alpha-2 agonist (increases/decreases) sympathetic tone due to inhibitory effects in CNS.
decreases
Which adrenergic receptor increases force (inotropy) and rate of contraction (chronotropy) in the heart?
beta-1
Which adrenergic receptor relaxes smooth muscle in respiratory, uterine, and vascular smooth muscle?
beta-2
which adrenergic receptor activates glycogenolyis in the human liver?
beta-2
Which adrenergic receptor promotes potassium uptake in skeletal muscle?
beta-2
Which adrenergic receptor dilates renal blood vessals in smooth muscle?
dopa-1
Which adrenergic receptors may induce natriuresis?
dopa-1 receptors