3. Results
3.1. Effects on INa of TTX or toxin extracts from muscle or liver
of eatable puffers
Voltage-dependent Na current (INa) was evoked by
a depolarizing step pulse with 10 ms duration in dissociated
CA1 neurons from holding potential (VH) of 70 to
30 mV. Fig. 2A shows representative INa traces with and
without toxin extracts from the muscle or liver of three
puffers (T. rubripes, L. wheeleri and T. vermicularis) that are
normally eaten. In the presence of these toxin extracts, INa
was inhibited within 10 s and recovered in several minutes
after washing out the extracts (Fig. 2C). Similar rapid
inhibition and slow recovery were observed in the presence
of tetrodotoxin (TTX, Sigma) at various concentrations
as shown in Fig. 2B.
Fig. 3 shows the variation in the effects of toxin extracts
from liver of six T. rubripes and five A. reticularis, on INa with
104 and 103 dilutions. It is evident that the six T. rubripes