Adrenergic Agonists Flashcards
Where does the sympathetic NS arise from? Describe their pre/post ganglionic fibers
Thoracolumbar
Short preganglionic
Long postganglionic
Where does the parasympathetic NS arise from? Describe their pre/post ganglionic fibers
Craniosacral
Long preganglionic
Short postganglionic
How is the adrenal gland innervated by the autonomic NS?
Sympathetic preganglionic from thoracic spine directly to adrenal medulla to induce epinephrine hormone secretion
What kind of neurotransmitters are involved in the sympathetic nervous system and what are their receptors?
Pre: ACh => Binds Nicotinic receptors
Post: NE => Binds adrenergic receptors
W?hat kind of neurotransmitters are involved in the parasympathetic nervous system and what are their receptors?
Pre: Ach => binds Nicotinic Receptors
Post: Ach => binds nicotinic and muscarinic receptors
What are the exceptions to the sympathetic neurotransmitter properties?
Sweat glands + some skeletal mucle in smooth muscle vasculature
What are the effects of parasympathetic stimulation
Miosis Bradycardia Bronchoconstriction Increased GI motility Increased bladder emptying
What are the effects of sympathetic stimulation?
Mydriasis Inc HR Inc Inotropy Bronchodilation Vascular constriction/diliation Decreasd GI motility Decreased Bladder emptying Increased blood sugar/glycogenolysis
What does Tyrosine Hydroxylase do?
Convert Tyrosine to Dopa, a precursor for Dopamine, which is a precursor for NE
Where is dopamine converted to NE?
In the synaptic vesicle
Where are a1 receptors found and what do they do?
Vascular Smooth Muscle: Vasoconstriction
Pupillary DIlator Muscle: Mydriasis
Pilomotor: Erect hair
Where are a2 receptors found and what do they do?
adrenergic/cholinergic nerve terminals: decrease neurotransmitter release
Some smooth muslce: Vasoconstriction
Where are B1 receptors found and what do they do?
Heart: Increase HR and Increase Inotropy
JGA: Increase Renin secretion
Where are B2 receptors found and what do they do?
Lungs: Bronchodilations Uterine/Vascular SMooth muscle: Relaxation Liver: Increase glycogenolysis Pancreatic B Cells: Increase insulin Somatic Nerve Terminals: Tremor
Where are D1 receptors found and what do they do?
Renal + Sphlancnic Blood vessels : Relax and vasodilate
Where are D2 receptors found and what do they do?
Nerve Terminals: Inhibit Adenylyl Cyclase
What G protein is a1 receptor coupled to and how does it act?
Gaq : activates PLC -> cleave PIP2 -> inc IP3 + DAG -> Activate MLCK -> Phosphorylate light chain myosin -> contraction
What G protein is a2 receptor coupled to and what does it do?
Gai: decrease cAMP -> inhibit PKA -> inhibit voltage gated Ca2+ channels -> decrease neurotransmitter release
What G protein is B1 receptor coupled to and what does it do?
Gas: opposite of a2; Activate AC -> inc cAMP -> inc PKA -> phosphorylate Calcium channels
What G protein is B2 receptor coupled 2 and what does it do?
Gas: opposite of a1; inc cAMP -> inc PKA -> phosphorylate MLCK -> decrease enzyme activity on calmodulin -> decrease phosphorylation of myosin light chain -> relaxation
What are the nonselective direct acting adrenomimet
NE
Epi
Dopamine
What are the a1 selective adrenomimetics?
Phenylephrine
What are the a2 selective adrenomimetics?
Clonidine
What are the nonselective B agonists?
Isoproterenol
What are the B1 selective agonists?
Dobutamine
What are the B2 selective agonists?
Albuterol
Terbutaline
What are the indirect acting adrenomimetics that release endogenous compounds?
Ephedrine
Pseudoephedrine
Tyramine
What are the indirect acting adrenomimetics thatinhibit reuptake?
Methylphenidate
Amphetamine
Methamphetamine
What is the efficacy ranking of a1 receptors?
Epi > NE»_space;» Isoproterenol
What is the efficacy ranking of a2 receptors?
Epi >= NE»_space;»> Isoproterenol
What is the efficacy ranking of B1 receptors?
Isoproternol > Epi»_space;» NE (not a full agonist)
What is the efficacy ranking of B2 receptors?
Isoproterenol > Epi =NE
Why do we see a decrease in diastolic BP with low dose Epi?
Activation of B2 receptors causing vasodilation
Why do we see an increase in diastolic BP with high dose epi?
Activation of a1 +a2 at increased levels override the effect of decreased diastolic bp from B2 receptor activation
What effects does Epi have?
Low dose: dec diastolic BP, inc CO
High Dose: Inc TPR + CO
Bronchodilaiton
Dec bronchial secretions
What are the indications for EPi
Anaphylaxis
Cardiac Arrest
Bronchospasm
What are the contraindications of Epi?
Late term pregnancy
What are the toxicities of Epi?
Arrhythmias, Cerebral Hemorrhage, Pulmonary Edema
What are the cardiovascular effects of NE?
Increased CO and Systolic BP from B1 receptor activation
Vasoconstriction leading to inc diastolic BP from a1+a2
Inc diastolic BP -> Baroreceptor reflex-> dec HR