Potencies

[virajpatel]

How would the potency of isoproterenol, NE and epi change for the beta-1 receptor if the NET reuptake is blocked by cocaine or TCA?

I figured the potencies for ISO=EPI=NE but is that not the case?

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[worldbeater]

All I can throw in here is to say that potency deals with competitive binding and moves along the x-axis. Not sure if that helps.

 

[virajpatel]

All I can throw in here is to say that potency deals with competitive binding and moves along the x-axis. Not sure if that helps.

No that did not help, its not really what i was looking for but hey its better than no reply. Thank you for the help!

 

[DandyLion]

I believe the relative potencies at beta receptors is ISO > EPI > NE

EDIT: I thought about your question again and understand your confusion. I'm curious to know the answer to this as well.

 

[virajpatel]

I believe the relative potencies at beta receptors is ISO > EPI > NE

Blocking NE reuptake would increase the local concentration of NE however this does not affect the potency of NE at that receptor. Potency refers to the amount of drug needed to produce a certain effect i.e. the less drug required to produce the same effect, the more potent. A greater concentration of NE would produce a larger effect by virtue of there being more around, however the potency has not changed.

EDIT: I thought about your question again and understand your confusion. I'm curious to know the answer to this as well.

I was told by my professor that they would be Iso>Epi=NE, however, when I asked for an explanation he didn't provide it. The problem with his answer that neither of the two options I was considering match his answer.

EDIT: I might have understood based on your explanation. So NET has a higher affinity for the NE than Epi but if it is blocked their potencies would be equal at the beta receptor, and the Iso, as is remains most potent since the NET does not uptake ISo because like you said the potency has to do with the amount of the drug needed to produce a response.