Involvement of class A calcium channels in the KCl induced Ca2+ influx in hippocampal synaptosomes.
Using Ca2+ channel toxins, we determined the types of voltage-sensitive calcium channels activated by two levels of KCl depolarization in hippocampal synaptosomes. The increase in the intracellular Ca2+ concentration ([Ca2+]i) induced by 30 mM KCl was equally sensitive to either omega-agatoxin IVA (omega-Aga IVA) or to omega-conotoxin MVIIC (omega-CgTx MVIIC), and the inhibition produced by these two peptides was not additive. The present results indicate that omega-Aga IVA and omega-CgTx MVIIC do not distinguish between two different VSCC in hippocampal synaptosomes and that they both inhibit a channel with the alpha 1A subunit which is present in the rat hippocampus.
Malva
J O
JO
Department of Zoology, University of Coimbra, Portugal.
Ambrósio
A F
AF
Carvalho
A P
AP
Duarte
C B
CB
Carvalho
C M
CM
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D015220:Calcium Channels / Q000187:drug effects / Q000378:metabolism*; D004594:Electrophysiology; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism*; D066298:In Vitro Techniques; D015640:Ion Channel Gating / Q000187:drug effects / Q000502:physiology; D008297:Male; D010455:Peptides / Q000494:pharmacology; D011189:Potassium Chloride / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D013111:Spider Venoms / Q000494:pharmacology; D013574:Synaptosomes / Q000187:drug effects / Q000378:metabolism*; D020867:omega-Agatoxin IVA; D020866:omega-Conotoxin GVIA; D020960:omega-Conotoxins
D002121:Calcium Channel Blockers; D015220:Calcium Channels; D010455:Peptides; D013111:Spider Venoms; D020867:omega-Agatoxin IVA; D020960:omega-Conotoxins; C075851:omega-conotoxin-MVIIC; D011189:Potassium Chloride; D020866:omega-Conotoxin GVIA; D002118:Calcium