ISSN:
1432-1912
Keywords:
Key words 5’-p-Fluorosulfonylbenzoyladenosine
;
ATP
;
β
;
γ-Methylene-ATP
;
Purinoceptor
;
cAMP
;
NG108-15 cells
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Abstract ATP is known to increase intracellular cAMP levels in NG108-15 cells via a novel purinoceptor and this response is inhibited by the P1 purinoceptor antagonist methylxanthine. In the present study, we examined the effects of 5’-p-fluorosulfonylbenzoyladenosine (FSBA), an affinity ligand for ATP-binding proteins, on cAMP formation mediated by activation of adenylate cyclase (AC)-linked purinoceptors in NG108-15 cells. cAMP levels were determined by RIA using an anti-succinyl-cAMP antiserum. FSBA (100 µM) increased intracellular cAMP about 2.6-fold. However, FSBA-induced cAMP formation was abolished by pretreatment with adenosine deaminase, suggesting that adenosine, a breakdown product of FSBA, is involved in FSBA-induced cAMP formation. In contrast, pretreatment of cells with FSBA in the presence of adenosine deaminase inhibited cAMP formation induced by ATP and β,γ-methylene-ATP (β,γ-MeATP), without affecting the prostaglandin E1 (PGE1)-induced response. The inhibitory effect of FSBA on ATP-induced cAMP formation was concentration-dependent with a concentration required for half-maximal inhibition (IC50) of around 3 µM. The inhibitory effect of FSBA was not affected by pertussis toxin (PTX)-treatment. Pretreatment with FSBA (10 µM) depressed the maximal response to β,γ-MeATP by 60%, but did not affect the response to 5’-N-ethylcarboxamidoadenosine. The inhibitory effect of FSBA (100 µM) increased time-dependently during pretreatment and partly resisted wash-out. The inhibition by FSBA was protected by simultaneous addition of β,γ-MeATP during the FSBA pretreatment, indicating that both FSBA and the ATP analogue interacted with the same receptor site. The pretreatment with FSBA did not affect the increase in [Ca2+]i induced by ATP, UTP or benzoylbenzoic ATP. These results suggest that FSBA inhibits cAMP accumulation induced in NG108-15 cells by ATP or related agonists by selective modification of an AC-linked purinoceptor.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/PL00005237
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