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Updated: Aug 18, 2026

Double-barreled and Concentric Microelectrodes for Measurement of Extracellular Ion Signals in Brain Tissue
Published on: September 5, 2015
Adenohypophysial transmembrane potentials: polarity reversal by elevated external potassium ion concentration
Abstract:
Incubation of rat adenohypophyses in potassium ion of sufficient concentration to provoke the release of several of the adenohypophysial trophic hormones produces a reversed, positive transmembrane potential in more than half the cells. This finding is consistent with a process of "stimulus-secretion coupling" in which hypothalamic releasing factors act by selective depolarization of their "target" cells. The positive potentials may be due to a prolonged preferential permeability to calcium ions triggered by an initial depolarization of the cell membrane to a threshold value by increased external potassium ion.
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