The effect of Huwentoxin-I on Ca2+ channels in differentiated NG108-15 cells, a patch-clamp study

Huwentoxin-I (HWTX-I), a 3.75 kDa peptide toxin isolated from the venom of the spider Selenocosmia huwena, was found to be a reversible presynaptic inhibitor by our previous work. Using whole-cell patch clamp methods, we found that HWTX-I had no significant effect on the TTX-sensitive Na+ current or the delayed rectifier K+ current (K-r) in low-serum medium cultured NG108-15 cells, but High-Voltage-Activated Ca2+ channel expressed in prostaglandin E-1 differentiated NG108-15 cells could be potently inhibited by HWTX-I (EC50 approximate to 100 nM), while it hardly affected low-voltage-activated Ca2+ channel. Among types of high-voltage-activated Ca2+ channel, HWTX-I selectively inhibited N-type Ca2+ channel and had only very weak effect on L-type Ca2+ channel in prostaglandin E-1 differentiated NG108-15 cells. (C) 2000 Elsevier Science Ltd. All rights reserved.