Increase in inositol tris-, pentakis- and hexakisphosphates by high K+ stimulation in cultured rat cerebellar granule cells.
Effects of high K+ stimulation on inositol polyphosphate accumulations and intracellular free calcium concentration ([Ca2+]i) were investigated in cultured rat cerebellar granule cells. When the [3H]inositol-labelled cells were stimulated with KCl, concentration-dependent accumulations of [3H]Ins(1,4,5)P3, [3H]InsP5 and [3H]InsP6 were observed. Nifedipine (3 microM), a calcium channel antagonist, inhibited the high (KCl, 90 mM) K(+)-induced accumulations of these inositol polyphosphates. In Ca(2+)-depleted and EGTA-containing (0.1 mM) medium, the high K(+)-induced inositol polyphosphate accumulation were completely inhibited. Similar results were also observed in the case of [Ca2+]i. These results suggest that the rise in [Ca2+]i caused by activation of voltage-dependent calcium channels plays an important roles in the high K(+)-induced accumulation of [3H]Ins(1,4,5)P3, [3H]InsP5 and [3H]InsP6 in cultured rat cerebellar granule cells.
Sasakawa
N
N
Department of Pharmacology, Keio University School of Medicine, Tokyo, Japan.
Nakaki
T
T
Kakinuma
E
E
Kato
R
R
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D002531:Cerebellum / Q000166:cytology / Q000378:metabolism*; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism*; D007295:Inositol Phosphates / Q000378:metabolism*; D007700:Kinetics; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D009543:Nifedipine / Q000494:pharmacology; D010833:Phytic Acid / Q000378:metabolism*; D011188:Potassium / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D013997:Time Factors
D007295:Inositol Phosphates; D010833:Phytic Acid; D015544:Inositol 1,4,5-Trisphosphate; D009543:Nifedipine; D011188:Potassium; D002118:Calcium