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Retired NBME 21 Answers

nbme21/Block 1/Question#48 (reveal difficulty score)
A 44-year-old man is admitted to the hospital ...
Increasing cGMP ๐Ÿ” / ๐Ÿ“บ / ๐ŸŒณ / ๐Ÿ“–
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 +9  upvote downvote
submitted by โˆ—divya(75)
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increase in cAMP (Gs) - beta2 - vasodilation

decrease in cAMP (Gi) - alpha2 - vasoconstriction

increase in IP3 DAG (Gq) - alpha1 - vasoconstriction

increase in cGMP - M3 - NO induced vasodilation

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cytotoxict  Alpha 2 agonists do not cause vasoconstriction b/c they lead to negative feedback of norepi and thus decrease sympathetic response +1
payingforthisisdumb  FA20 p317 ฮฑ2-agonists increase NO/cGMP and vasodilate +
sarahs  why is decreasing cAMP wrong? +1
hiroshimi  @sarahs: you want to increase cAMP because it would lead to vasodilation and help to decrease his blood pressure. Decreasing cAMP would make his BP worse. +
fatboyslim  alpha2 stimulation causes vasodilation because it is sympatholytic. +

simple rule of thumb is

Calcium --> vasoconstriction (smooth muscle constriction) -- > must be Gq (alpha 1, v1)

rise in cAMP and cGMP both vasodilation (cAMP by inhibiting MLCK, cGMP by activating MLCP) so whoever causes vasodialation must increase either. cGMP is niche (NO, ANP) so most of the time it is rise in cAMP --> must be Gs (beta 2)

only exception is M3 it rises calcium (Gq) but in endothelial cells , not vascular smooth m. cells, so NO produced and causes vasodialation via rise in cGMP (again!)


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 +2  upvote downvote
submitted by โˆ—vi_capsule(21)
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HTN emergency, Sodium Nitroprusside. Unlike hydralazine a balanced vasodilator (vein = arteriol)

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sympathetikey  Well then, I guess we should just forget about our old pals the Alpha-2 agonists. Good call. I didn't even see that this was hypertensive emergency. Dumb on my part. +
zup  so yea clonidine would be used for hypertensive urgency, but this guy is over 180 (210) so they have to use something like hydralazine or nitroprusside both will increase cGMP +
whoissaad  Drugs used to treat HTN emergency: Nitroprusside Labetolol Nicardipine Clevidpine Fenoldapam Clonidine +18
lola915  Hydralazine actually vasodilates arteries>veins and Nitroprusside vasodilates arteries = veins. Both increase cGMP. +12
vi_capsule  SO this site goes after money now! at least my comments aren't scrambled lol +2


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