title: Post-tetanic hyperpolarization and electrogenic Na pump in stretch receptor neurone of crayfish.
abstract: 1. Two types of after-potentials in the stretch receptor neurone of crayfish are described.2. A short-duration after-hyperpolarization associated with a single spike or a few spikes is diminished and reversed on applying hyperpolarizing currents. However, a much longer-lasting post-tetanic hyperpolarization (PTH) is enhanced by conditioning hyperpolarization; thus, no reversal potential can be obtained.3. No changes in membrane conductance occur during PTH.4. Reducing K concentration in the bathing fluid diminishes PTH, while it shifts the reversal potential of the short after-potential toward greater negativity.5. Replacement of Na with Li, or addition of 2,4-dinitrophenol in the bathing fluid suppresses PTH in a reversible manner.6. Electrophoretic injection of Na into the cell induces a long-lasting hyperpolarization.7. No change in K-equilibrium potential, as indicated by the reversal point of the short after-potential, is detected during PTH.8. It is concluded that the short after-potential is caused by a permeability increase for potassium ion, whereas PTH is produced by an electrogenic Na-pump.
mesh_terms: D000200:Action Potentials; D000818:Animals; D001692:Biological Transport; D002463:Cell Membrane Permeability; D003445:Crustacea; D004140:Dinitrophenols / Q000494:pharmacology; D008094:Lithium / Q000494:pharmacology; D008564:Membrane Potentials; D009119:Muscle Contraction / Q000502:physiology*; D009470:Muscle Spindles / Q000502:physiology; D009469:Neuromuscular Junction / Q000502:physiology; D009474:Neurons / Q000502:physiology*; D011188:Potassium / Q000494:pharmacology*; D011984:Sensory Receptor Cells / Q000502:physiology*; D012964:Sodium / Q000378:metabolism*
chemical_list: D004140:Dinitrophenols; D008094:Lithium; D012964:Sodium; D011188:Potassium