Two tetrodotoxin-resistant sodium channels in human dorsal root ganglion neurons

Two tetrodotoxin-resistant (TTX-R) voltage-gated sodium channels, SNS and N aN, are preferentially expressed in small dorsal root ganglia (DRG) and tri geminal ganglia neurons, most of which are nociceptive, of rat and mouse. W e report here the sequence of NaN from human DRG, and demonstrate the prese nce of two TTX-R currents in human DRG neurons. One current has physiologic al properties similar to those reported for SNS, while the other displays h yperpolarized voltage-dependence and persistent kinetics; a similar TTX-R c urrent was recently identified in DRG neurons of sns-null mouse. Thus SNS a nd NaN channels appear to produce different currents in human DRG neurons. (C) 1999 Federation of European Biochemical Societies.