Enkephalin inhibits release of substance P from sensory neurons in culture and decreases action potential duration.
Sensory neurons grown in dispersed cell culture in the absence of non-neuronal cell types contain immunoreactive substance P that is chemically similar to synthetic substance P. When depolarized in high-K+ media (30-120 mM), the neurons release this peptide by a Ca2+-dependent mechanism. An enkephalin analogue, [D-Ala2]enkephalin amide, at 10 micron inhibits the K+-evoked release of substance P. At the same or lower concentrations, [D-Ala2]enkephalin amide and enkephalin decrease the duration of the Ca2+ action potential evoked and recorded in dorsal root ganglion cell bodies without affecting the resting membrane potential or resting membrane conductance. This modulation of voltage-sensitive channels may account for the inhibition of substance P release.
D000200:Action Potentials / Q000187:drug effects*; D000818:Animals; D002478:Cells, Cultured; D002642:Chick Embryo; D004553:Electric Conductivity; D004723:Endorphins / Q000494:pharmacology*; D004745:Enkephalins / Q000494:pharmacology*; D005727:Ganglia, Spinal / Q000187:drug effects* / Q000378:metabolism; D008564:Membrane Potentials / Q000187:drug effects; D009411:Nerve Endings / Q000187:drug effects; D013373:Substance P / Q000378:metabolism*; D009435:Synaptic Transmission / Q000187:drug effects*
D004723:Endorphins; D004745:Enkephalins; D013373:Substance P