nadiabarati
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3. After taking an overdose of propranolol, a 35 yr old woman developes sinus bradycardia and syncope. In order to stimulate the same second messenger system that is activated by ¦Â-adrenergic receptors, which of the following drugs will be most effective to increase her heart rate? A. ADH (Vasopressin)
B. Atrial Natriuretic peptide
C. Clonidine
D. Glucagon
E. Phenylephrine
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| leen
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same q is discussed in other thread
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| robin082006
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D
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| aisha2
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well i think D come close , WHY ? bcoz thats the only thing in this list that stimulates cAMP sytem , i found this chart one a web that might help some of us to understand this concept.
from the answers given above , glucagon is obvious bcoz in FA has given that GLUCAGON is used for Beta blocker toxicity, and although Phenylephrine & Clonidine are the Alph2 agonist they work via the PIP2 system .
i could not find any thing about glucagon wokrs via which receptor , as thats was some thing botherin me
anyway thats how im goin to remember this is that propanolol ( beta blocker ) decreases cAMP and glocagon increases cAMP
Cyclic AMP Epinephrine and norepinephrine, glucagon, luteinizing hormone, follicle stimulating hormone, thyroid-stimulating hormone, calcitonin, parathyroid hormone, antidiuretic hormone
Protein kinase activity Insulin, growth hormone, prolactin, oxytocin, erythropoietin, several growth factors
Calcium and/or phosphoinositides Epinephrine and norepinephrine, angiotensin II, antidiuretic hormone, gonadotropin-releasing hormone, thyroid-releasing hormone.
Cyclic GMP Atrial - naturetic hormone, nitric oxide
Glucagon binds its receptor in the plasma membrane of target cells (e.g. hepatocytes).
Bound receptor interacts with and, through a set of G proteins, turns on adenylate cyclase, which is also an integral membrane protein.
Activated adenylate cyclase begins to convert ATP to cyclic AMP, resulting in an elevated intracellular concentration of cAMP.
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| tolito
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hi aisha2,
check out this thread.
http://www.prep4usmle.com/forum/thread/31473
heart has Glucagon receptors which are G prot linked.
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