Flow cytometric analysis with a fluorescently labeled @entity435 peptide receptor ligand as a new method to study the pharmacological profile of the XXXX H2 receptor.

@entity268 @entity1 @entity5038 @entity50478 @entity460 @entity112 @entity141 @entity941 @entity435
The @entity112 H2 receptor ( @entity50478 ) is a Gs protein-coupled receptor. Its activation leads to increases in the second messenger @entity268 ( @entity268 ). Presently, several systems are established to characterize the pharmacological profile of the H2R, mostly requiring radioactive material, animal models, or @entity1 blood cells. This prompted us to establish a flow cytometric analysis with a fluorescently labeled @entity435 peptide receptor (FPR) ligand in order to investigate the H2R functionally and pharmacologically. First, we stimulated U937 promonocytes, which mature in a @entity268 -dependent fashion upon H2R activation, with @entity112 (HA) or selective H2R agonists and measured increases in @entity268 concentrations by mass spectrometry. Next, indicative for the maturation of U937 promonocytes, we assessed the FPR expression upon incubation with HA or H2R agonists. FPR expression was measured either indirectly by @entity435 peptide-induced changes in intracellular @entity460 concentrations ([ @entity141 ]i) or directly with the @entity941 -labeled FPR ligand fNleLFNleYK-Fl. HA and H2R agonists concentration-dependently induced FPR expression, and potencies and efficacies of @entity5038 -induced increases in [ @entity141 ]i and FPR density correlated linearly. Accordingly, flow cytometric analysis of FPR expression constitutes a simple, inexpensive, sensitive, and reliable method to characterize the H2R pharmacologically. Furthermore, we evaluated FPR expression at the mRNA level. Generally, quantitative real-time polymerase chain reaction confirmed functional data. Additionally, our study supports the concept of functional selectivity of the H2R, since we observed dissociations in the efficacies of HA and H2R agonists in @entity268 accumulation and FPR expression.
