ISSN:
1432-2013
Keywords:
UTP
;
ATP
;
Nucleotides
;
M-currents
;
K currents
;
Neuroblastoma
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Abstract A phospholipase-C-linked nucleotide receptor, sensitive to both uridine and adenosine triphosphate (UTP and ATP) has been cloned from NG108-15 neuroblastoma × glioma hybrid cells. We have tested whether activation of this receptor could inhibit the voltage-dependent K+ current [I K(M) or “M-current”] in NG108-15 cells recorded using whole-cell patch-clamp methods. Both UTP and ATP inhibited I K(M) by 44% and 42%, respectively, at 100 μM. Mean IC50 values were: UTP, 0.77±0.27 μM; ATP, 1.81±0.82 μM. The order of nucleotide and nucleoside activity at 100 μM was: UTP = ATP 〉 ATP[γS] = ITP 〉 2 MeSATP 〉 ADP = GTP ≫ AMP-CPP, adenosine, where ATP[γS] is adenosine 5′-O-(3-thiotriphosphate), ITP is inosine 5′-triphosphate, 2-MeSATP is 2-methylthio ATP and AMP-CPP is α,β methylene ATP. This rank order accords with their activities at the cloned P2U receptor. Effects were not inhibited by suramin (up to 500 μM) or by pre-incubation for 12 h in 500 ng·ml−1 Pertussis toxin. Inhibition of IK(M) was frequently preceded by a transient outward current, probably a Ca2+-activated K+ current, responding to Ca2+ mobilization. No effect on the delayed rectifier K+ current was observed. These observations match those expected from stimulating other phospholipase-C-linked receptors in NG108-15 cells.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00374316
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