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Old 02-20-2012
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Default Norepinephrine and epinephrine question

Based on the attached figure... explain the changes in BP when adding phentolamine and propanolol.
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Old 02-21-2012
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Quote:
Originally Posted by Dr. Mexito View Post
Based on the attached figure... explain the changes in BP when adding phentolamine and propanolol.
ok..here we go:

Isoproterenol: acts on beta1 and 2
+ Phentolamine (alpha-blocker) -> nothing happens
+ Propranolol (unselective beta-blocker) -> bye bye isoproterenol-effect

Epinephrine (acts on alpha 1&2 and beta 1&2)
+Phentolamine -> epinephrine reversal (they really love this one on the USMLE)
+ Propranolol -> nothing happens

Norepinephrine (actson alpba1&2 > beta1)
+Phentolamine -> only beta 1 effect
+ Proranolol -> only alpha effect

hope this helps any corrections are wellcome
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Old 02-21-2012
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Isoproterenol ......B1 and B2 agonist so decrease in BP not affected by phenatolamine but propanol reduces its effect ......

Epinephrine acts on alpha 1 , 2 B 1, 2 ..... so phenatolamine blocks alpha 1 , 2 thus it now acts on B1, 2 so decrease in BP here propanolol block B so it acts on alpha and inc BP

Nor epinephrine only alpha 1, 2 no Beta so ..... phenatolamine dec its effect and propanolol has no effect on it .......

do post the original picture too ....
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Old 02-21-2012
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Default Yeap...

Was this too easy?
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Old 02-29-2012
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Quote:
Originally Posted by MedPharm View Post
ok..here we go:

Isoproterenol: acts on beta1 and 2
+ Phentolamine (alpha-blocker) -> nothing happens
+ Propranolol (unselective beta-blocker) -> bye bye isoproterenol-effect

Epinephrine (acts on alpha 1&2 and beta 1&2)
+Phentolamine -> epinephrine reversal (they really love this one on the USMLE)
+ Propranolol -> nothing happens

Norepinephrine (actson alpba1&2 > beta1)
+Phentolamine -> only beta 1 effect
+ Proranolol -> only alpha effect

hope this helps any corrections are wellcome
Thanks for the explanation, I'm having a hard time when it comes to makes this tables. To deduce which medication was given by looking at the graphics. Do you have any advice that it could help me to improve this???

Thanks in advances...
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Old 02-29-2012
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Quote:
Originally Posted by Dr. Mexito View Post
Thanks for the explanation, I'm having a hard time when it comes to makes this tables. To deduce which medication was given by looking at the graphics. Do you have any advice that it could help me to improve this???

Thanks in advances...
i know what you mean...i think they r one of the hardest qs...
i handle them a lot 'by feeling' - i studied the FA pages (pharmacology of the autonomic drugs) and tried to get a good basic understanding, u know just such stuff as: mecamylamine and hexamethonium get rid of all ganglionic reactions, or bethanechol, pilocarpine, methacholine -> all challenge tests - but why?
and i thought it over and over and over again...and with a bit of luck i get them right....
does that help you
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Old 02-29-2012
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Quote:
Originally Posted by Dr. Mexito View Post
Thanks for the explanation, I'm having a hard time when it comes to makes this tables. To deduce which medication was given by looking at the graphics. Do you have any advice that it could help me to improve this???

Thanks in advances...
I know the feeling as well, my advise is to first now by heart what those drugs/neurotransmitters do and which receptos they stimulate.
Then know what reflex will happen (most of the time reflex change in heart rate)
go step by step and also know that pretreatment with a ganglionic blocker will stop any reflex change ; rest is easy i guess
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Old 02-29-2012
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Hola Dr. Mexito, i think i read you studied pharmacology from Katzung right?... if so, check kaplan lecture notes, i believe they have many examples.

take care man!
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