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Antagonism of an adenosine/ATP receptor in follicular Xenopus oocytes.

King, Brian F., Wildman, Scott S.P., Townsend-Nicholson, A., Burnstock, Geoffrey (1998) Antagonism of an adenosine/ATP receptor in follicular Xenopus oocytes. The Journal of Pharmacology and Experimental Therapeutics, 285 (3). pp. 1005-1011. ISSN 0022-3565. E-ISSN 1521-0103. (Access to this publication is currently restricted. You may be able to access a copy if URLs are provided) (KAR id:52956)

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Follicular Xenopus oocytes possess a novel receptor where both adenosine and ATP activate a cAMP-dependent, nonrectifying K+-current. Five compounds, alpha,beta-methylene ATP (alpha, beta-meATP), 8-(p-sulfophenyl)theophylline (8-SPT), theophylline, 2, 2'-pyridylisatogen tosylate (PIT) and suramin, were tested as antagonists of adenosine- and ATP-activated K+-currents. The descending order of activity (pIC50 values) against adenosine responses was: alpha,beta-meATP (6.72) = 8-SPT (6.68) > theophylline (5.32) > PIT (4.58), whereas suramin was relatively inactive. The blocking actions of alpha,beta-meATP and alkylxanthine compounds were reversible with washout, whereas blockade by PIT was irreversible. These antagonists showed similar blocking activity against ATP responses, except for PIT which was more effective at ATP responses than at adenosine responses. The selectivity of antagonists was tested against cAMP-dependent K+-currents evoked by forskolin and follicle-stimulating hormone (FSH). 8-SPT and theophylline did not inhibit but instead augmented forskolin and FSH responses; this augmentation may be caused by inhibition of phosphodiesterase activity inside follicle cells. On the other hand, alpha,beta-MeATP and PIT inhibited forskolin and FSH responses; both compounds apparently are nonselective antagonists. Thus, only alkylxanthine derivatives (8-SPT and theophylline) were selective antagonists of the novel adenosine/ATP receptor in Xenopus oocytes, whereas alpha,beta-meATP and PIT were nonselective in their blocking actions and suramin was relatively inactive.

Item Type: Article
Subjects: R Medicine > RM Therapeutics. Pharmacology
Divisions: Divisions > Division of Natural Sciences > Medway School of Pharmacy
Depositing User: Scott S.P. Wildman
Date Deposited: 09 Dec 2015 16:33 UTC
Last Modified: 16 Nov 2021 10:22 UTC
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