Regulation of the potassium current and cytosolic Ca2+ release induced by 2-methylthio ATP in hippocampal neurons.
A potent P2Y purinoceptor agonist, 2-methylthio ATP (2-MeSATP), produced whole-cell potassium currents through a purinoceptor linked to a pertussis toxin (PTX)-insensitive G-protein in rat hippocampal neurons. The currents were not affected by a selective protein kinase C or A inhibitor. Single channel recordings demonstrated that the potassium channel is activated without latency even in outside-out patches. These suggest that the channel may be regulated directly by the beta gamma subunits of a G-protein. In addition, 2-MeSATP enhanced intracellular free Ca2+ concentration ([Ca2+]i) with a very rapid initiation time. The [Ca2+]i increase was inhibited by a broad G-protein inhibitor, but not by a phospholipase C (PLC) inhibitor or an IP3 receptor antagonist. These indicate that this Ca2+ mobilization may be regulated by a mechanism independent of a PLC-mediated phosphatidylinositol signaling pathway.
Ikeuchi
Y
Y
Department of Physiology, Kobe University School of Medicine, Japan.
Nishizaki
T
T
Mori
M
M
Okada
Y
Y
D000255:Adenosine Triphosphate / Q000031:analogs & derivatives* / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000502:physiology; D003600:Cytosol / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000502:physiology; D006624:Hippocampus / Q000502:physiology*; D015640:Ion Channel Gating / Q000502:physiology; D009474:Neurons / Q000378:metabolism; D011188:Potassium / Q000502:physiology*; D015221:Potassium Channels / Q000502:physiology*; D011493:Protein Kinase C / Q000502:physiology; D058913:Purinergic Agonists; D051381:Rats; D011983:Receptors, Purinergic / Q000502:physiology*; D015290:Second Messenger Systems; D015398:Signal Transduction; D013873:Thionucleotides / Q000494:pharmacology*; D010738:Type C Phospholipases / Q000502:physiology
D015221:Potassium Channels; D058913:Purinergic Agonists; D011983:Receptors, Purinergic; D013873:Thionucleotides; D000255:Adenosine Triphosphate; D017868:Cyclic AMP-Dependent Protein Kinases; D011493:Protein Kinase C; D010738:Type C Phospholipases; D019204:GTP-Binding Proteins; D011188:Potassium; D002118:Calcium; C008501:2-methylthio-ATP