Tetrodotoxin-blockable depolarization-activated Na+ currents in a cultured endothelial cell line derived from rat interlobar arter and human umbilical vein.

Voltage-dependent Na+ current (INa) was identified in cultured endothelial cells derived from rat interlobar artery (RIAE cells) and human umbilical vein (HUVE cells). Tetrodotoxin (TTX) reduced INa in a dose-dependent manner with the apparent dissociation constant (Kd) of 1.4 microM. Low sensitivity of INa to TTX as well as its kinetics and voltage-dependent properties indicates that voltage-gated Na channels expressed in vascular endothelial cells belong to the so-called TTX-resistant type.