Ca2+ channel activating action of maitotoxin in cultured brainstem neurons.
The actions of maitotoxin were studied using cultured brainstem cells and adrenal chromaffin cells. Maitotoxin induced a profound increase in the Ca2+ influx into cultured brainstem cells after a brief lag period. The maitotoxin-induced Ca2+ influx was suppressed by various voltage-dependent Ca2+ channel blockers such as Co2+, Mn2+, verapamil and diltiazem. Maitotoxin-catecholamine release in brainstem cells initiated to increase after a lag period of about 1 min and the increase continued even at 4 min after treatment, while in the adrenal chromaffin cells the release started after an about 1-min lag period to attain a maximum within first 2-min and gradually decrease thereafter. These results suggest that maitotoxin acts on Ca2+ channels to increase the Ca2+ influx, accompanied by enhancement of catecholamine release in the brainstem cells with a different temporal profile from that in the adrenal chromaffin cells.
Department of Pharmaceutical Molecular Biology, Graduate School of Pharmaceutical Sciences, Tohoku University, Aoba, Aramaki, Aoba-ku, Sendai 980-8578, Japan.
Atsushi
A
Kakizaki
Masami
M
Takahashi
Hiroyuki
H
Akagi
Eiichi
E
Tachikawa
Toshifumi
T
Yamamoto
Eiichi
E
Taira
Tohru
T
Yamakuni
Yasushi
Y
Ohizumi
D000818:Animals; D001933:Brain Stem; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D015220:Calcium Channels / Q000502:physiology*; D002132:Calcium Radioisotopes; D002395:Catecholamines / Q000378:metabolism; D002417:Cattle; D002478:Cells, Cultured; D019439:Chromaffin Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005333:Fetus; D008387:Marine Toxins / Q000494:pharmacology*; D009474:Neurons / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D009529:Nicardipine / Q000494:pharmacology; D009638:Norepinephrine / Q000378:metabolism; D035964:Oxocins / Q000494:pharmacology*; D011188:Potassium / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D013779:Tetrodotoxin / Q000494:pharmacology; D013997:Time Factors; D014316:Tritium; D014700:Verapamil / Q000494:pharmacology; D000095702:Polyether Toxins
D002118:Calcium; D002121:Calcium Channel Blockers; D015220:Calcium Channels; D002132:Calcium Radioisotopes; D002395:Catecholamines; D008387:Marine Toxins; D009529:Nicardipine; D009638:Norepinephrine; D035964:Oxocins; D011188:Potassium; D013779:Tetrodotoxin; D014316:Tritium; D014700:Verapamil; C020394:maitotoxin; D000095702:Polyether Toxins