TY - JOUR T1 - The Sea Anemone Toxins BgII and BgIII Prolong the Inactivation Time Course of the Tetrodotoxin-Sensitive Sodium Current in Rat Dorsal Root Ganglion Neurons JF - Journal of Pharmacology and Experimental Therapeutics JO - J Pharmacol Exp Ther SP - 1067 LP - 1074 DO - 10.1124/jpet.102.038570 VL - 303 IS - 3 AU - Emilio Salceda AU - Anoland Garateix AU - Enrique Soto Y1 - 2002/12/01 UR - http://jpet.aspetjournals.org/content/303/3/1067.abstract N2 - We have characterized the effects of BgII and BgIII, two sea anemone peptides with almost identical sequences (they only differ by a single amino acid), on neuronal sodium currents using the whole-cell patch-clamp technique. Neurons of dorsal root ganglia of Wistar rats (P5-9) in primary culture (Leibovitz′s L15 medium; 37°C, 95% air/5% CO2) were used for this study (n = 154). These cells express two sodium current subtypes: tetrodotoxin-sensitive (TTX-S; K i = 0.3 nM) and tetrodotoxin-resistant (TTX-R;K i = 100 μM). Neither BgII nor BgIII had significant effects on TTX-R sodium current. Both BgII and BgIII produced a concentration-dependent slowing of the TTX-S sodium current inactivation (IC50 = 4.1 ± 1.2 and 11.9 ± 1.4 μM, respectively), with no significant effects on activation time course or current peak amplitude. For comparison, the concentration-dependent action of Anemonia sulcata toxin II (ATX-II), a well characterized anemone toxin, on the TTX-S current was also studied. ATX-II also produced a slowing of the TTX-S sodium current inactivation, with an IC50 value of 9.6 ± 1.2 μM indicating that BgII was 2.3 times more potent than ATX-II and 2.9 times more potent than BgIII in decreasing the inactivation time constant (τh) of the sodium current in dorsal root ganglion neurons. The action of BgIII was voltage-dependent, with significant effects at voltages below −10 mV. Our results suggest that BgII and BgIII affect voltage-gated sodium channels in a similar fashion to other sea anemone toxins and α-scorpion toxins. ER -