Assessment of α2-adrenoceptor antagonist potency with GTPase assay

• Published in: European journal of pharmacology Vol. 338; no. 3; pp. 293 - 296
• Main Authors: Virolainen, Sami, Jansson, Christian C, Scheinin, Mika
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 12.11.1997; Elsevier
• Subjects: Antagonist potency; Biological and medical sciences; Cell receptors; Cell structures and functions; CHO cell; Fundamental and applied biological sciences. Psychology; GTPase; Molecular and cellular biology; Monoamines receptors (catecholamine, serotonine, histamine, acetylcholine); α2-Adrenoceptor subtype; α 2-Adrenoceptor subtype; GTPase; CHO cell; Antagonist potency; α2-Adrenergic receptor; Enzyme; Triphosphoric monoester hydrolases; Rodentia; dGTPase; Esterases; Selectivity; In vitro; CHO cell line; Vertebrata; Biological fixation; Mammalia; Enzymatic activity; Animal; Plasma membrane; Hydrolases; Affinity; Models; Antagonist; Recombinant protein; Subtype; Hamster
• ISSN: 0014-2999; 1879-0712
• DOI: 10.1016/S0014-2999(97)81933-4

Membranes from Chinese hamster ovary (CHO) cells expressing high densities of α 2A-, α 2B- or α 2C-adrenoceptor subtypes were used to monitor potencies of α 2-adrenoceptor antagonists with a GTPase assay. Receptor-activated high-affinity GTPase activity was determined by measuring the rate of release of 32 P from [ γ- 32 P ]GTP. Concentration–response curves to the full agonist (−)-noradrenaline were obtained in the presence of different antagonist concentrations and p A 2 values were calculated by Schild analysis. Three antagonists (rauwolscine, prazosin and chlorpromazine) showed subtype-selectivity, which agrees with earlier radioligand binding results. We suggest that the GTPase assay described here is useful for characterization of the functional potency and subtype-selectivity of α 2-adrenoceptor antagonists.