Exam 2 Flashcards
What is the first messenger of a GPCR?
Ligand that binds the GPCR
What are examples of ligands?
NE, Epi, Ach
What does the effector of a GPCR do?
activates the 2nd messenger
What are the names of effectors?
Adenylate Cyclase, Phospholipase C, Guanylate Cyclase (nitrodilators)
What does a second messenger do?
elicits a specific response
What are the second messengers?
cAMP, cGMP, inositol triphosphate, diacylglycerol, Ca
Explain the GPCR pathway of Phenylephrine?
Phenylephrine binds to a A-1 Gq protein, Increasing phospholipase C, Increase IP3 DAG and Ca, causing muscle contraction
Explain the GPCR pathway of Precedex?
Precedex binds to a A-2 Gi protein, decreasing adenylate cyclase , decreasing cAMP, causing contraction and transient HTN
What happens in the Cardiac Myocyte when you give a Beta-1 or Beta-2 drug?
Activates adenylate cyclase, increasing cAMP, which increases protein kinase A, which increases calcium release and muscle contraction.
What happens in the smooth muscle when you give a Beta-2 drug?
Increases cAMP which inhibits myosin light chain kinase, leading to vasodilation
What are both endogenous and exogenous sympathomimetic drugs?
epinephrine, norepinephrine, and dopamine
What sympathomimetic drugs are just exogenous?
isoproterenol, and dobutamine
What is the naturally occurring catecholamine synthesized from tyrosine in the adrenal medulla?
Epinephrine
What are the catecholamines secreted by the adrenal medulla and their percentages?
80% Epi 20 % Norepinephrine
Do endogenous or exogenous catecholamines have a longer effect in the body?
Endogenous
What happens if you give MAOIs with Ephedrine?
HTN crisis or exaggerated response
What receptors does Epinephrine act on?
A-1, A-2, B-1, B-2
What is the Beta-1 effect seen with Epinephrine?
positive inotropy, chronotropy, and dromotropy
What is the Beta-2 effect seen with Epinephrine?
smooth muscle relaxation, mast cell stabilization
Which receptors does low dose Epi target more?
Beta more than alpha
At what dose of Epi do you see just Beta effects?
0.01-0.03 mcg/kg/min
At what dose of Epi do you see Beta and a little alpha effects?
0.03-0.1 mcg/kg/min
At what dose of Epi do you see Alpha and Beta effects?
Greater than 0.1 mcg/kg/min
What is epinephrine used to treat?
low CO, anaphylaxis, bronchospasm













