Fluorescent H1 histamine receptor antagonist (apparent KD values are 8.07, 5.37 and >6 for H1, H2 and H3 receptors respectively). Also antagonizes the activity of Histamine, a H1 histamine receptor agonist. Displays no intrinsic activity. A fluorescent mepyramine analogue.
Figure 1. H1-SPAP cells assayed against histamine and 1 µM HB7824
Figure 2. H2-SPAP cells assayed against histamine and 1 µM HB7824
Fluorescence imaging with HB7824
HB7824 ligand (100 nM) binding to CHO cells expressing histamine H1 receptors. Binding to CHO-H1 cells blocked by the unlabelled competitor triprolidine (1 µM). No binding of H7824 to host CHO Cells (not expressing H1 receptors). Nuclei counter-stained with Hoechst.
Figure 1. H1-SPAP cells assayed against histamine and 1 µM HB7824
Figure 2. H2-SPAP cells assayed against histamine and 1 µM HB7824
Fluorescence imaging with HB7824
HB7824 ligand (100 nM) binding to CHO cells expressing histamine H1 receptors. Binding to CHO-H1 cells blocked by the unlabelled competitor triprolidine (1 µM). No binding of H7824 to host CHO Cells (not expressing H1 receptors). Nuclei counter-stained with Hoechst.
For imaging at the H1 receptor use solutions up to 100 nM.
Pharmacological validation
The CellAura fluorescent H1 antagonist [mepyramine] ligand was shown to antagonize the activity of the H1 agonist, histamine, in the recombinant CHO cell line expressing the human H1 receptor, co-transfected with a serum response element-induced secreted placental alkaline phosphatase (SPAP) reporter gene.
For the H1 expressing cell line, the serum-induced expression of SPAP was measured under basal and 1% serum-stimulated (maximal) conditions.
Addition of CellAura fluorescent H1 antagonist [mepyramine] to the basal or serum-stimulated cells did not significantly alter basal and stimulated SPAP levels, demonstrating that CellAura fluorescent H1 antagonist [mepyramine] has no intrinsic agonist activity.
To determine the apparent KD for CellAura fluorescent H1 antagonist [mepyramine] at histamine H1 receptors, cells were treated with varying concentrations of histamine agonist alone, or in the presence of 1µM CellAura fluorescent H1 antagonist [mepyramine], and the serum-induced expression of SPAP measured. The apparent KD at H1 was calculated from the rightward shift of the agonist response curve in the presence of CellAura fluorescent H1 antagonist [mepyramine], compared to the response curve for the agonist alone.
Similar studies were conducted with the CellAura fluorescent H1 antagonist [mepyramine] ligand using recombinant CHO cell lines expressing either the human H2 receptor or the human H3 receptor and a cyclic AMP-responsive secreted placental alkaline phosphatase (SPAP) reporter gene. The apparent KD at H2 was calculated in the same way to that calculated for the human H1 receptor.
Solubility & Handling
Storage instructions
-20°C (protect from light)
Solubility overview
Soluble in DMSO
Handling
After thawing individual aliquots for use, we recommend briefly sonicating the sample to ensure it is fully dissolved and the solution is homogeneous. We do not recommend using the product after subjecting it to repetitive freeze-thaw cycles.
Shipping conditions
The product, supplied in a dry form, is stable at ambient temperature for periods of up to a few days and does not require shipping on ice/dry ice.
Important
This product is for RESEARCH USE ONLY and is not intended for therapeutic or diagnostic use. Not for human or veterinary use.
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