Ca(2+) influx through nonselective cation channels plays an essential role in endothelin-1-induced mitogenesis in C6 glioma cells.
Ca(2+) channels activated by endothelin-1 (ET-1) in C6 glioma cells (C6 cells) were characterized using whole-cell patch-clamps and by monitoring the intracellular free Ca(2+) concentration ([Ca(2+)](i)), when administering Ca(2+) channel blockers such as LOE 908 and SK&F 96365. Using this methodology, the Ca(2+) channels involved in ET-1-induced mitogenesis were identified. The patch-clamp study and [Ca(2+)](i) monitoring showed that 10 nM ET-1 activated two types of Ca(2+)-permeable nonselective cation channels (NSCC); one was sensitive to LOE 908 but resistant to SK&F 96365 (NSCC-1) and the other was sensitive to both LOE 908 and SK&F 96365 (NSCC-2). Conversely, 0.1 nM ET-1 activated only NSCC-1.ET-1-induced mitogenesis in a concentration-dependent manner, with the maximum effect arising at concentrations > or =10 nM. LOE 908 completely suppressed the 10 nM ET-1-induced mitogenesis, whereas SK&F 96365 only partially suppressed it. The IC(50) values of these blockers for the ET-1-induced mitogenesis were similar to those for the 10 nM ET-1-induced increase in [Ca(2+)](i). In contrast, LOE 908 completely suppressed 0.1 nM ET-1-induced mitogenesis, whereas SK&F 96365 did not affect it.Collectively, these results demonstrate that the sustained increase in [Ca(2+)](i), via NSCC-1 and NSCC-2, may be essential for ET-1-induced mitogenesis in C6 cells. Moreover, the sensitivity of NSCC-1 to ET-1 is higher than that of NSCC-2 to ET-1.
Kawanabe
Y
Y
Department of Neurosurgery, Kyoto University Faculty of Medicine, Sakyo-ku, Kyoto 606-8507, Japan. kawanabe@kuhp.kyoto-u.ac.jp
Hashimoto
N
N
Masaki
T
T
D000081:Acetamides / Q000494:pharmacology; D000818:Animals; D001932:Brain Neoplasms / Q000473:pathology*; D002118:Calcium / Q000378:metabolism*; D002455:Cell Division; D002460:Cell Line; D004594:Electrophysiology; D019332:Endothelin-1 / Q000494:pharmacology*; D005910:Glioma / Q000473:pathology*; D007093:Imidazoles / Q000494:pharmacology; D007473:Ion Channels / Q000187:drug effects / Q000378:metabolism*; D007546:Isoquinolines / Q000494:pharmacology; D008938:Mitosis / Q000187:drug effects*; D018408:Patch-Clamp Techniques; D051381:Rats; D014407:Tumor Cells, Cultured
D000081:Acetamides; D019332:Endothelin-1; D007093:Imidazoles; D007473:Ion Channels; D007546:Isoquinolines; C081356:LOE 908; C063159:1-(2-(3-(4-methoxyphenyl)propoxy)-4-methoxyphenylethyl)-1H-imidazole; D002118:Calcium