Differential effects of calcium channel antagonists on tityustoxin and ouabain-induced release of [3H]acetylcholine from brain cortical slices.
In this paper, the effect of calcium channel blockers on acetylcholine release induced by tityustoxin and ouabain in rat brain cortical slices is described. Cadmium, a non-specific blocker of calcium channels, inhibited the release of ACh induced by tityustoxin. L-type calcium channel blockers (verapamil, nifedipine and diltiazen) had no effect on the release of ACh induced by tityustoxin. The release of ACh was also unaffected by nickel, a T-type calcium channel blocker, and the conotoxins GVIA and MVIIC, blockers of N and Q-type calcium channels. Agatoxin IVA, a specific blocker of the P-type calcium channel, inhibited the release of ACh induced by tityustoxin by 50%. The spontaneous release of ACh as well as ouabain-induced release of ACh was unaffected by any of the calcium channel blockers studied. It is concluded that ACh release induced by tityustoxin is mediated by Ca2+ influx via P-type calcium channels.
Casali
T A
TA
Departamento de Farmacologia, ICB, UFMG-Belo, Horizonte-Minas, Gerais, Brasil.
Gomez
R S
RS
Moraes-Santos
T
T
Gomez
M V
MV
D000109:Acetylcholine / Q000378:metabolism*; D000818:Animals; D002104:Cadmium / Q000494:pharmacology; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D002540:Cerebral Cortex / Q000187:drug effects*; D005260:Female; D008297:Male; D009498:Neurotoxins / Q000494:pharmacology*; D009532:Nickel / Q000494:pharmacology; D010042:Ouabain / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D012604:Scorpion Venoms / Q000494:pharmacology*
D002121:Calcium Channel Blockers; D009498:Neurotoxins; D012604:Scorpion Venoms; D002104:Cadmium; C003609:tityustoxin; D010042:Ouabain; D009532:Nickel; D000109:Acetylcholine