Substance P-induced depolarization accompanied by a decrease in membrane input resistance in the hamster submandibular ganglion cell.

We described in a previous paper (Bull Tokyo dent Coll 33: 33-35, 1992) that the submandibular ganglion cells (SMG) of hamster responded to substance P (SP) with a depolarization, which could be divided into three subtypes according to the change in membrane input resistance (Rm) during depolarization: depolarizations accompanied by either an increase or a decrease in Rm, and without change in Rm. In this study, the generation mechanism of the SP-induced depolarization accompanied by a decrease in Rm was investigated using the current-clamp technique. The result showed that cation channels coupled with NK-1 receptors on SMG cells were involved in generation of the SP-depolarization, and that the main charge carrier was the sodium ion.