Substance P opens cation channels and closes potassium channels in rat locus coeruleus neurons.
Whole-cell recordings were made from neurons of the rat locus coeruleus in a tissue slice removed from rat brain. Substance P caused an inward current in cells voltage-clamped at -60 mV. The effect of substance P was concentration-dependent (30 nM-3 microM) and was mimicked by similar concentrations of substance K and neuromedin K. The inward current resulted predominantly from an increase in membrane cation conductance; in potassium-free solutions it reversed polarity at about 12 mV. Substance P also reduced the conductance of an inwardly rectifying potassium current; this action was studied with low external sodium concentration. It is concluded that substance P excites rat locus coeruleus neurons by activating an intracellular transduction pathway leading to both cation conductance increase and potassium conductance decrease.
D000818:Animals; D002118:Calcium / Q000494:pharmacology; D002412:Cations; D002712:Chlorides / Q000494:pharmacology; D066298:In Vitro Techniques; D015640:Ion Channel Gating / Q000187:drug effects*; D007473:Ion Channels / Q000187:drug effects* / Q000502:physiology; D008125:Locus Coeruleus / Q000502:physiology*; D008274:Magnesium / Q000494:pharmacology; D008564:Membrane Potentials / Q000187:drug effects; D015288:Neurokinin A / Q000494:pharmacology; D015287:Neurokinin B / Q000494:pharmacology; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D011188:Potassium / Q000494:pharmacology; D015221:Potassium Channels / Q000187:drug effects* / Q000502:physiology; D051381:Rats; D013373:Substance P / Q000494:pharmacology*; D013779:Tetrodotoxin / Q000494:pharmacology
D002412:Cations; D002712:Chlorides; D007473:Ion Channels; D015221:Potassium Channels; D013373:Substance P; D013779:Tetrodotoxin; D015288:Neurokinin A; D015287:Neurokinin B; D008274:Magnesium; D011188:Potassium; D002118:Calcium