title: Substance P inhibits the M-current in bullfrog sympathetic neurones.
abstract: Substance P (SP, 2.5-10 microM) was applied by rapid bath perfusion to bullfrog lumbar sympathetic neurones in vitro, voltage-clamped through a single micro-electrode. In unclamped cells, SP produced a depolarization accompanied by an increase in apparent input resistance. Under voltage-clamp a voltage-dependent inward current was induced by SP, during which the time-dependent relaxations induced by square voltage commands were inhibited. It is concluded that SP inhibits the M-current (IM), a species of voltage-dependent K+-current, and that IM-inhibition was the primary cause of the inward current and membrane depolarization in the cells tested.
mesh_terms: D000818:Animals; D005728:Ganglia, Sympathetic / Q000187:drug effects* / Q000502:physiology; D066298:In Vitro Techniques; D007473:Ion Channels / Q000187:drug effects*; D011188:Potassium / Q000378:metabolism*; D011892:Rana catesbeiana; D013373:Substance P / Q000494:pharmacology*
chemical_list: D007473:Ion Channels; D013373:Substance P; D011188:Potassium