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Outward Currents in Rat Entorhinal Cortex Stellate Cells Studied with Conventional and Perforated Patch Recordings
Author(s) -
Eder C.,
Ficker E.,
Gündel J.,
Heinemann U.
Publication year - 1991
Publication title -
european journal of neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.346
H-Index - 206
eISSN - 1460-9568
pISSN - 0953-816X
DOI - 10.1111/j.1460-9568.1991.tb00060.x
Subject(s) - tetraethylammonium , cardiac transient outward potassium current , patch clamp , electrophysiology , chemistry , depolarization , biophysics , entorhinal cortex , current (fluid) , 4 aminopyridine , neuroscience , potassium channel , potassium , biology , hippocampus , physics , organic chemistry , thermodynamics
We have studied outward currents of neurons acutely isolated from superficial layers of the entorhinal cortex with whole‐cell patch‐clamp recordings. If cells were held more negative than ‐50 mV, depolarizing voltage commands activated a transient A‐type current together with a sustained outward current. Both currents were sensitive to 4‐aminopyridine, while only the sustained current was blocked by tetraethylammonium. The sustained outward current showed a considerable rundown in amplitude over prolonged recording periods. At the same time its half‐maximal inactivation shifted from ‐74 to ‐ 114 mV. Nystatin perforated patch recordings were used to minimize these perfusion effects. Under such conditions the amplitude and the steady‐state inactivation properties of the sustained outward current remained stable for more than 1 h. Pharmacological investigations revealed that only a small part of the sustained outward current could be attributed to a calcium‐activated potassium current. Therefore most of the rundown has to be due to changes in the delayed rectifier outward current. These results may suggest that the delayed rectifier current is under considerable metabolic control.