ISSN:
1432-1424
Keywords:
ATP
;
FRTL-5
;
thyroid gland
;
chloride currents
;
inositol trisphosphate
;
calcium
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Chemistry and Pharmacology
Notes:
Summary The effect of external ATP on both the membrane potential and the transmembrane current of the thyroid cell line FRTL-5 has been investigated in the patch-clamp whole-cell recording configuration. In the resting situation the membrane potential is around −70 mV and the membrane acts like a K+-sensitive electrode. Application of ATP at concentrations higher than 1 μ M elicited an increase in Cl− conductance, responsible for a membrane depolarization which could be blocked by preincubation with the P2-antagonist quinidine. Chelation of intracellular Ca2+ also blocked the ATP induced changes in membrane potential and Cl− current. Intracellular perfusion with inositol trisphosphate (IP3) (50 μ M) also stimulated a Cl− current which mimicked the response induced by ATP. ATP is able to initiate a response in the absence of extracellular Ca2+, but also opens a Ca2+-influx pathway, as demonstrated by a secondary response upon Ca2+ readmission in the external medium, in the continued presence of ATP. ADP and ATP-γS were able to mimic the ATP response, whereas AMP and adenosine were unable to elicit a Cl− current. The P2X receptor agonist α,β-methyleneATP was without effect as was the P2Y receptor agonist 2-methylthio ATP. We conclude that ATP is able to elicit a large IP3-mediated Ca2+-dependent Cl− current and membrane depolarization via a novel P2-type purinergic receptor.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00236437
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