title: Cell dialysis by sharp electrodes can cause nonphysiological changes in neuron properties.
abstract: We recorded from lobster and leech neurons with two sharp electrodes filled with solutions often used with these preparations (lobster: 0.6 M K2SO4 or 2.5 M KAc; leech: 4 M KAc), with solutions approximately matching neuron cytoplasm ion concentrations, and with 6.5 M KAc (lobster, leech) and 0.6 M KAc (lobster). We measured membrane potential, input resistance, and transient and sustained depolarization-activated outward current amplitudes in leech and these neuron properties and hyperpolarization-activated current time constant in lobster, every 10 min for 60 min after electrode penetration. Neuron properties varied with electrode fill. For fills with molarities ≥2.5 M, neuron properties also varied strongly with time after electrode penetration. Depending on the property being examined, these variations could be large. In leech, cell size also increased with noncytoplasmic fills. The changes in neuron properties could be due to the ions being injected from the electrodes during current injection. We tested this possibility in lobster with the 2.5 M KAc electrode fill by making measurements only 10 and 60 min after penetration. Neuron properties still changed, although the changes were less extreme. Making measurements every 2 min showed that the time-dependent variations in neuron properties occurred in concert with each other. Neuron property changes with high molarity electrode-fill solutions were great enough to decrease neuron firing strongly. An experiment with (14)C-glucose electrode fill confirmed earlier work showing substantial leak from sharp electrodes. Sharp electrode work should thus be performed with cytoplasm-matched electrode fills.
authors.affiliation: Department of Biological Sciences, Ohio University, Athens, Ohio; and Zoologisches Institut, Universität zu Köln, Köln, Germany.
authors.forename: Scott L
authors.initials: SL
authors.lastname: Hooper
authors.affiliation: Department of Biological Sciences, Ohio University, Athens, Ohio; and thuma@ohio.edu.
authors.forename: Jeffrey B
authors.initials: JB
authors.lastname: Thuma
authors.affiliation: Department of Biological Sciences, Ohio University, Athens, Ohio; and Zoologisches Institut, Universität zu Köln, Köln, Germany.
authors.forename: Christoph
authors.initials: C
authors.lastname: Guschlbauer
authors.affiliation: Zoologisches Institut, Universität zu Köln, Köln, Germany.
authors.forename: Joachim
authors.initials: J
authors.lastname: Schmidt
authors.affiliation: Zoologisches Institut, Universität zu Köln, Köln, Germany.
authors.forename: Ansgar
authors.initials: A
authors.lastname: Büschges
mesh_terms: D000818:Animals; D002250:Carbon Radioisotopes; D048429:Cell Size; D017097:Electric Impedance; D004566:Electrodes; D017952:Ganglia, Invertebrate / Q000502:physiology; D006652:Histological Techniques / Q000295:instrumentation; D007477:Ions / Q000378:metabolism; D007865:Leeches; D008564:Membrane Potentials; D009474:Neurons / Q000502:physiology*; D033521:Palinuridae; D018408:Patch-Clamp Techniques / Q000295:instrumentation; D013997:Time Factors
chemical_list: D002250:Carbon Radioisotopes; D007477:Ions
keywords: current injection; leech; neuron properties; stomatogastric