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Functional characterization of A1 adenoosine receptors by photoaffinity labelling

Please always quote using this URN: urn:nbn:de:bvb:20-opus-86097
  • The ligand-binding subunit ofthe A1 adenosine receptor has been identified in membranes with the photoaffinity Iabel R-2-azido-N6-p-hydroxyphenylisopropyladenosine (R-AHPIA). Covalent labelling ofthe A1 receptor can also be achieved in intact cells. The dissociation of the radioiodinated label (1251-AHPIA) from isolated rat fat cells was incomplete after UV irradiation, leaving about 20°/o of irreversible specific binding. Such covalent labelling of the receptor led to a concentration-dependent reduction of cellular cyclic AMP levels. ThisThe ligand-binding subunit ofthe A1 adenosine receptor has been identified in membranes with the photoaffinity Iabel R-2-azido-N6-p-hydroxyphenylisopropyladenosine (R-AHPIA). Covalent labelling ofthe A1 receptor can also be achieved in intact cells. The dissociation of the radioiodinated label (1251-AHPIA) from isolated rat fat cells was incomplete after UV irradiation, leaving about 20°/o of irreversible specific binding. Such covalent labelling of the receptor led to a concentration-dependent reduction of cellular cyclic AMP levels. This persistent effect of covalent labeHing occurred with an IC50 value of 9 nM, as compared to an IC50 value of 0.9 nM for the direct reduction of cyclic AMP Ievels by the ligand. The difference in the IC5o values can be explained by assuming spare receptors. This hypothesis was verified in binding studies using [ 3HJPIA as a radioligand. R-AHPIA inhibited binding of [3H)PIA to intact fat cells with a K1 value of about 20 nM, which is about 20 tim es high er than the corresponding IC50 value of cyclic AMP reduction. These data show that the A1 receptor is activated according to the occupancy theory. The high sensitivity of the activation in intact ceJis is due to a large number of spare receptors.show moreshow less

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Metadaten
Author: Martin J. Lohse, Karl-Norbert Klotz, Ulrich Schwabe
URN:urn:nbn:de:bvb:20-opus-86097
Document Type:Book article / Book chapter
Faculties:Medizinische Fakultät / Institut für Pharmakologie und Toxikologie
Language:English
Year of Completion:1987
Source:In: Topics and perspectives in adenosine research / Eckehart Gerlach ... (Eds.). - Berlin [u.a.]: Springer, 1987. - S.15-22. - ISBN: 0-387-17364-0
Dewey Decimal Classification:6 Technik, Medizin, angewandte Wissenschaften / 61 Medizin und Gesundheit / 610 Medizin und Gesundheit
GND Keyword:Adenosinrezeptor
Release Date:2014/06/03
Licence (German):License LogoDeutsches Urheberrecht