Pentylenetetrazole suppresses the potassium current in Euhadra neurons which is coupled with Ca2+/calmodulin-dependent protein phosphorylation.
The Ca2+/calmodulin-dependent protein phosphorylation-related mechanism underlying pentylenetetrazole (PTZ)-induced reduction of delayed potassium current (IKD) was examined in identified Euhadra neurons. PTZ gradually reduced peak IKD in a dose-dependent manner, as well as an inhibition of Ca2+/calmodulin-dependent protein phosphorylation. Similar effects were observed by a general protein kinase inhibitor, 1-(5-isoquinolinylsulfonyl)-2-methylpoperazine, whose saturating dose occluded the action of PTZ on the IKD. Intracellular injection of Ca2+/calmodulin-dependent protein kinase II transiently restored the PTZ-suppressed IKD nearly to the pre-PTZ level, whereas either CaCl2 or calmodulin, injected in the same way, had little effect. However, this restoration was not detectable in the presence of N-(6-aminohexyl)-5-chloronaphthalenesulfonamide, a calmodulin inhibitor, in the perfusate. These results suggest that PTZ suppresses the potassium current coupled with Ca2+/calmodulin-dependent protein phosphorylation.
Onozuka
M
M
Department of Anatomy, Gifu University School of Medicine, Japan.
Tsujitani
M
M
D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D002147:Calmodulin / Q000494:pharmacology*; D004553:Electric Conductivity; D007546:Isoquinolines / Q000494:pharmacology; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D009474:Neurons / Q000502:physiology*; D010433:Pentylenetetrazole / Q000494:pharmacology*; D010766:Phosphorylation; D010879:Piperazines / Q000494:pharmacology; D011188:Potassium / Q000502:physiology*; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000494:pharmacology; D012908:Snails
D002147:Calmodulin; D007546:Isoquinolines; D009419:Nerve Tissue Proteins; D010879:Piperazines; D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D011493:Protein Kinase C; D011188:Potassium; D002118:Calcium; D010433:Pentylenetetrazole