Development of a steady electric current in neonatal rat lumbrical muscle.
We have used a vibrating probe and intracellular recording techniques to study the development of a steady electric current generated by rat lumbrical muscle. In adult animals, previous work has revealed a steady outward current generated at the end plate region. In the present study, we show that at birth muscles generate a steady inward, not outward current. The inward current declines with age, disappearing about 5 days after birth. At about the same time, the steady outward current appears, and reaches adult amplitude by 2-3 weeks after birth. The two currents are generated by completely different mechanisms. The inward current is blocked by alpha-bungarotoxin and apparently results from activation of acetylcholine-gated channels at the end plate. The outward current, on the other hand, is not affected by alpha-bungarotoxin but is blocked by agents which interfere with chloride movements across the membrane, as in the adult.
D000818:Animals; D000831:Animals, Newborn / Q000254:growth & development*; D001464:Barium / Q000378:metabolism; D002038:Bungarotoxins / Q000494:pharmacology; D002712:Chlorides / Q000378:metabolism; D004553:Electric Conductivity; D004594:Electrophysiology; D005665:Furosemide / Q000494:pharmacology; D007700:Kinetics; D024510:Muscle Development; D011188:Potassium / Q000378:metabolism; D012964:Sodium / Q000378:metabolism; D013997:Time Factors; D014732:Vibration
D002038:Bungarotoxins; D002712:Chlorides; D001464:Barium; D005665:Furosemide; D012964:Sodium; D011188:Potassium