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INTRACELLULAR AND WHOLE‐CELL RECORDINGS FROM ZONA‐FREE HAMSTER EGGS: SIGNIFICANCE OF LEAK IMPALEMENT ARTIFACT
Author(s) -
Georgiou P.,
Bountra C.,
House C. R.
Publication year - 1987
Publication title -
quarterly journal of experimental physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.925
H-Index - 101
eISSN - 1469-445X
pISSN - 0144-8757
DOI - 10.1113/expphysiol.1987.sp003036
Subject(s) - depolarization , membrane potential , omega , electrode , electrophysiology , chemistry , pipette , biophysics , analytical chemistry (journal) , biology , physics , chromatography , physiology , quantum mechanics
Measurements have been made of membrane potential and input resistance of zona‐free hamster eggs from single micro‐electrode recordings. At room temperature (20‐23 °C) the mean (±S.D.) values for the potential and resistance were ‐30 ± 8 mV and 280 ± 130 MC ( n = 94 eggs). At 37 °C the mean (±S.D.) values for the potential and resistance were ‐39 ± 13 mV and 230 ± 60 MΩ ( n = 60 eggs). The most negative potential recorded at room temperature was ‐51 mV in a cell which had an input resistance of 620 MΩ. At 37 °C six eggs out of sixty had potentials more negative than ‐50 mV and three of these gave all‐or‐none action potentials in response to depolarizing current pulses. In a separate series of experiments with high resistance micro‐electrodes ( ca1 . 100 MΩ) six eggs out of twenty‐one had potentials more negative than ‐50 mV and four of these were electrically excitable. Transient potential recordings during impalement indicated that the potential was more negative than ‐30 mV but that the insertion of a micro‐electrode produced a leak pathway with a resistance of about 10 MΩ, substantially smaller than the steady‐state estimates of the input resistance (see above). Whole‐cell recordings with patch pipettes gave potentials in the range ‐30 to ‐80 mV and input resistances in the range 180 to 350 MΩ ( n = 8); four eggs gave action potentials in response to depolarizing current pulses passed through the patch pipette. It is concluded that the leak impalement artifact is so significant in micro‐electrode recordings from hamster eggs that it prevents routine reliable potential measurements.