NBME sympathomimetic Q

[LuckiestOne]

---

Members do not see this ad.

The question asks about a drug that increase the effect of vasoconstriction via NE in vitro blood vessel segment.

The answer choices are:

Cocaine
Guanethidine
Isoproterenol
Metoprolol
Phenoxybenzamine
Reserpine
Tyramine.

I picked Cocaine because I remembered somewhere it could also cause in vitro vasoconstriction although it is an indirect enhancer that inhibits reuptake...

Some people say the answer may be Metoprolol because metoprolol binds to some of the beta receptors to allow NE to work more closely with the Alpha 1 receptors.

Any thoughts?

 

[thehundredthone]

In vitro segments are denervated, so indirect agonists can't really do much. Metoprolol is a beta 1 selective, not sure what difference that would make for vasoconstriction.

Your answer is probably correct, it is cocaine. Cocaine's vasoconstrictive action is not fully understood. It is proposed that it might be mediated by the release of ET-1 from endothelium (as seen in in vitro studies). This might help.
cardiovascres.oxfordjournals.org/content/31/1/117.full.pdf