...how to know if some antagonist effect is non-competitive?

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Hss's picture
...how to know if some antagonist effect is non-competitive?


I´m working with some antagonist for blocking the current evoked with one agonist and I need to get some evidence or idea if the way of action is competitive or non-competitive. How can I check it? Should I applied one constant amount of antagonist and just increase the among of agonist? 


The FFM's picture
Yes you have the correct idea

Yes you have the correct idea.

The effect of a competitive antagonist can be overcome by increasing the concentration of the agonist.  You will see a rightward shift ( increased EC50) in the agonist dose response curve with no decrease in the maximal response.

For a non-competitive antagonist, once the inhibition has been fully established, no dose of agonist will relive the inihibition.  The non competitive antagonist will reduce the magnitude of the maximum response.  In theory there should be no shift in the the agonist EC50 (as long as there is no receptor reserve present in the system http://www.ncbi.nlm.nih.gov/pubmed/8318718) .

Hss's picture
 For now I need some fast and

 For now I need some fast and not so difficult indication or evidence that the effect is or not competitive. Do you think that if I increase two to three times the agonist during the antagonism effect, if the response don´t increase so much, can I take as indication that the effect is non-competitive?