Naþ current in standard solution without TTX. Dose–inhibition
curves were fitted with Origin Software (OriginLab,
Northampton, MA) to a sigmoidal dose–response equation
for IC50 value determination. The potencies of the toxin
extract to inhibit INa were expressed as an amount of
equipotent TTX, comparing the IC50 obtained from dilution–inhibition
curve and dose–inhibition curve for TTX.
Data were presented as mean standard error of mean
(SEM). The significance between groups was tested by
analysis of variance (ANOVA), and P < 0.05 was considered
significant.