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The Interaction of U-73122 With the Histamine H1 Receptor: Implications for the Use of U-73122 in Defining H1 Receptor-Coupled Signalling Pathways

The Interaction of U-73122 With the Histamine H1 Receptor: Implications for the Use of U-73122 in Defining H1 Receptor-Coupled Signalling Pathways

S A Hughes, W J Gibson, J M Young

Naunyn Schmiedebergs Arch Pharmacol. 2000 Dec;362(6):555-8.

PMID: 11138848

Abstract:

U-73122, an N-aminosteroid homologue of N-ethylmaleimide (NEM), widely used as an inhibitor of phospholipase C, was found to be a potent inhibitor (IC50 5.5+/-0.5 microM) of the binding of [3H]mepyramine to guinea-pig cerebellar membranes. The succinimido analogue, U-73343, also inhibited the binding of [3H]mepyramine (estimated IC50 24+/-1 microM), but NEM was only a weak inhibitor, even at 10 mM. The interaction of U-73122 and U-73343 with the H1 receptor was effectively irreversible, on the time-scale of the experiment. There is no indication that reaction with a receptor thiol residue is involved in the binding of U-73122, since preincubation of membranes with 2 mM NEM did not significantly increase the IC50 for the inhibition of [3H]mepyramine binding by U-73122. We conclude that U-73122 binds to the histamine H1 receptor in the concentration range in which it acts as an inhibitor or PLC. This compromises the use of U-73122 to provide evidence that an H1 agonist action is mediated via PLC. The tight binding of U-73343 to the receptor appears to be primarily a function of the hydrophobic nature of the compound.

Chemicals Related in the Paper:

Catalog Number	Product Name	Structure	CAS Number	Price
AP142878124-A	U-73343		142878-12-4	Price

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