Drug receptor kinetics is as a key component in drug discovery, development, and efficacy; however, determining kinetic parameters has historically required direct radiolabeling or competition with a labeled tracer. Here we present a simple approach to determining the kinetics of competitive antagonists of G protein-coupled receptors by exploiting the phenomenon of hemi-equilibrium, the state of partial re-equilibration of agonist, antagonist, and receptor in some functional assays. Using functional [Ca(2+)]i-flux and extracellular kinases 1 and 2 phosphorylation assays that have short incubation times and therefore are prone to hemi-equilibrium "behaviors," we investigated a wide range of structurally and physicochemically distinct muscarinic acetylcholine receptor antagonists. Using a combined operational and hemi-equilibrium model of antagonism to both simulate and analyze data, we derived estimates of association and dissociation rates for the test set of antagonists, identifying both rapidly dissociating (4-DAMP, himbacine) and slowly dissociating (tiotropium, glycopyrrolate) ligands. The results demonstrate the importance of assay incubation time and the degree of receptor reserve in applying the analytical model. There was an excellent correlation between estimates of antagonist pK(B), k(on), and k(off) from functional assays and those determined by competition kinetics using whole-cell [(3)H]N-methylscopolamine binding, validating this approach as a rapid and simple method to functionally profile receptor kinetics of competitive antagonists in the absence of a labeled tracer.
Download full-text PDF |
Source |
---|---|
http://dx.doi.org/10.1124/mol.115.100545 | DOI Listing |
CNS Drugs
January 2025
New York State Psychiatric Institute, 1051 Riverside Drive, New York, NY, 10032, USA.
Xi Bao Yu Fen Zi Mian Yi Xue Za Zhi
January 2025
Department of Integrated Traditional Chinese and Western Medicine, Shandong First Medical University Affiliated Cancer Hospital, Jinan 250117, China. *Corresponding author, E-mail:
It has been popular and challenging to undertake researches on the delay of acquired resistance of epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKI). As key cells for tumor initiation, cancer stem cells (CSC) play an important role in the process of resistance to EGFR-TKI. Although preliminary studies found that traditional Chinese medicine (TCM) could inhibit CSC properties and delay EGFR-TKI resistance, the specific molecular mechanism remains unclear.
View Article and Find Full Text PDFJ Neurol Neurosurg Psychiatry
January 2025
Department of Neurology, Medical Faculty, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
Background: Myasthenia gravis (MG) is an autoimmune disorder affecting neuromuscular junctions, leading to fluctuating muscle weakness. While many patients respond well to standard immunosuppression, a substantial subgroup faces ongoing disease activity. Emerging treatments such as complement factor C5 inhibition (C5IT) and neonatal Fc receptor (FcRn) antagonism hold promise for these patients.
View Article and Find Full Text PDFJ Neurol Neurosurg Psychiatry
January 2025
Department for Neuromuscular Disease, National Hospital for Neurology and Neurosurgery, Queen Square, London, UK.
Background: We report our experience of patients with generalised myasthenia gravis (gMG) treated with efgartigimod, an neonatal Fc receptor antagonist, under the Early Access to Medicine Scheme (EAMS) in the UK.
Methods: Data from all UK patients treated with efgartigimod under the EAMS July 2022 to July 2023 were collected retrospectively. Efgartigimod was administered as per the ADAPT protocol (consisting of a treatment cycle of four infusions at weekly intervals with further cycles given according to clinical need).
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!