Paradoxical dose-reponse curves

Duke Groebe drg at prophet.pharm.pitt.edu
Mon Sep 25 13:50:06 EST 1995


In article <446mhh$4pf at fremont.ohsu.edu>, Matt Jones <jonesmat at ohsu.edu>
wrote:
  
> Can you please give more information about what is meant by
> "paradoxical"? Many drugs can give "bell-shaped" curves, where the
> response increases with dose at low concentrations, reaches a maximum,
> and then decreases at high concentrations. Simple explanations for this
> usually postulate two separate processes being induced by the same drug.
> An example is the action of ACh a nicotinic receptors. At low to moderate
> concentrations ACh activates channel opening, but at high concentrations
> it appears to block the channel, reducing current. The bell shaped curve
> probably results from the combination of a high affinity site of agonism,
> and a low affinity site for block. 
> 
> -Matt


Whoa, Matt.  I see you need to read up on nAChR function.

Duke

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