Reagent Details

Imaging information

For imaging at the H2 receptor use solutions up to 100 nM.

Pharmacological Validation

The CA200821 ligand was shown to antagonize the activity of the H2 agonist, histamine, in a recombinant CHO cell line expressing the human H2 receptor and a cyclic AMP-responsive secreted placental alkaline phosphatase (SPAP) reporter gene. No antagonist activity of the CA200821 ligand was detected at the highest concentration tested in a recombinant cell line expressing human H1 receptor provided by Applied Cell Sciences (Rockville, MD 20850, USA. Catalogue number: A665).

For the H2 expressing cell line, the cyclic AMP-induced expression of SPAP was measured under basal and forskolin-stimulated (maximal) conditions. Addition of CA200821 to the basal or forskolin-stimulated cells did not significantly alter basal and stimulated SPAP levels, demonstrating that CA200821 has no intrinsic agonist activity.

To determine the apparent KD for CA200821 at histamine H2 receptors, cells were treated with varying concentrations of histamine agonist alone, or in the presence of 1µM CA200821, and the cyclic AMP-induced expression of SPAP measured.

The apparent KD at H2 was calculated from the rightward shift of the agonist response curve in the presence of CA200821, compared to the response curve for the agonist alone.