Phoneutria nigriventer toxins block tityustoxin-induced calcium influx in synaptosomes.
Neurotoxins can help the understanding of mechanisms involved in neurotransmission. We here report that two neurotoxin isoforms, Tx3-3 and Tx3-4 obtained from the venom of the spider Phoneutria nigriventer inhibited the 45Ca2+ influx in rat cortical synaptosomes induced by the scorpion venom tityustoxin. The IC50 for Tx3-3 and Tx3-4 were 0.32 and 7.9 nM, respectively. The neurotoxins Tx3-3 and Tx3-4 are very effective in inhibiting 45Ca2+ influx and they should be useful in studies involving Ca(2+)-dependent processes.
Miranda
D M
DM
Departmento de Farmacologia, ICB-UFMG, Belo Horizonte-MG, Brasil.
Romano-Silva
M A
MA
Kalapothakis
E
E
Diniz
C R
CR
Cordeiro
M N
MN
Santos
T M
TM
Prado
M A
MA
Gomez
M V
MV
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002132:Calcium Radioisotopes; D002540:Cerebral Cortex / Q000378:metabolism*; D007700:Kinetics; D009479:Neuropeptides / Q000494:pharmacology*; D009498:Neurotoxins / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D012604:Scorpion Venoms / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D013111:Spider Venoms / Q000494:pharmacology; D013574:Synaptosomes / Q000187:drug effects / Q000378:metabolism*
D002132:Calcium Radioisotopes; D009479:Neuropeptides; D009498:Neurotoxins; D012604:Scorpion Venoms; D013111:Spider Venoms; C098736:Tx3 neurotoxin; C003609:tityustoxin; D002118:Calcium