Neurotrophic substance develops tetrodotoxin-sensitive action potential and increases curare-sensitivity of acetylcholine response in cultured rat myotubes.
We examined the trophic effects of a partially purified trophic substance from mouse spinal cord extract on the tetrodotoxin (TTX)-sensitivity of action potentials and on acetylcholine-sensitivity of rat skeletal myotubes in 7- and 8-day-old cultures. Many myotubes grown in control medium generate action potentials in the presence of TTX (10(-6) M). The addition of fraction E (Fr.E) from a Biogel P2 column, which exhibited trophic activity on adult denervated muscle in organ culture, decreased TTX-resistivity of action potentials of myotubes in cell culture. The trophic substance was also effective when further purified by paper chromatography and electrophoresis. The response to iontophoretically applied acetylcholine of Fr.E-treated myotubes was much more reduced by D-tubocurarine (10(-7) g/ml) than those of control cultured myotubes. No difference in morphological differentiation, protein synthesis, creatine phosphokinase activity or specific binding of [125I]alpha-bungarotoxin was observed between control and Fr.E-treated cultures. These results suggest that the trophic substance in Fr.E may be involved in the normal development of TTX-sensitive sodium channels and of acetylcholine receptor properties.
D000109:Acetylcholine / Q000494:pharmacology*; D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects; D003402:Creatine Kinase / Q000378:metabolism; D046508:Culture Techniques; D003472:Curare / Q000494:pharmacology*; D004247:DNA / Q000096:biosynthesis; D008564:Membrane Potentials / Q000187:drug effects; D009132:Muscles / Q000294:innervation*; D009414:Nerve Growth Factors / Q000494:pharmacology; D009419:Nerve Tissue Proteins / Q000096:biosynthesis; D051381:Rats; D013116:Spinal Cord / Q000032:analysis*; D013779:Tetrodotoxin / Q000494:pharmacology*; D014020:Tissue Extracts / Q000494:pharmacology*
D009414:Nerve Growth Factors; D009419:Nerve Tissue Proteins; D014020:Tissue Extracts; D013779:Tetrodotoxin; D003472:Curare; D004247:DNA; D003402:Creatine Kinase; D000109:Acetylcholine