Stimulatory actions of di-8-butyl-amino-naphthyl-ethylene-pyridinium- propyl-sulfonate (di-8-ANEPPS), voltage-sensitive dye, on the BKCa channel in pituitary tumor (GH3) cells

Sheng-Nan Wu, Ming Wei Lin, Ya Jean Wang

Research output: Contribution to journalArticle

4 Citations (Scopus)


Di-8-ANEPPS (4-{2-[6-(dibutylamino)-2-naphthalenyl]-ethenyl}-1-(3- sulfopropyl)pyridinium inner salt) has been used as a fast-response voltage-sensitive styrylpyridinium probe. However, little is known regarding the mechanism of di-8-ANEPPS actions on ion currents. In this study, the effects of this dye on ion currents were investigated in pituitary GH3 cells. In whole-cell configuration, di-8-ANEPPS (10 μM) reversibly increased the amplitude of Ca2+-activated K+ current. In inside-out configuration, di-8-ANEPPS (10 μM) applied to the intracellular surface of the membrane caused no change in single-channel conductance; however, it did enhance the activity of large-conductance Ca2+-activated K + (BKCa) channels with an EC50 value of 7.5 μM. This compound caused a left shift in the activation curve of BK Ca channels with no change in the gating charge of these channels. A decrease in mean closed time of the channels was seen in the presence of this dye. In the cell-attached mode, di-8-ANEPPS applied on the extracellular side of the membrane also activated BKCa channels. However, neither voltage-gated K+ nor ether-à-go-go-related gene (erg)-mediated K+ currents in GH3 cells were affected by di-8-APPNES. Under current-clamp configuration, di-8-ANEPPS (10 μM) decreased the firing of action potentials in GH3 cells. In pancreatic βTC-6 cells, di-8-APPNES (10 μM) also increased BKCa-channel activity. Taken together, this study suggests that during the exposure to di-8-ANEPPS, the stimulatory effects on BKCa channels could be one of potential mechanisms through which it may affect cell excitability.

Original languageEnglish
Pages (from-to)687-699
Number of pages13
JournalPflugers Archiv European Journal of Physiology
Issue number4
Publication statusPublished - 2008 Jan 1

All Science Journal Classification (ASJC) codes

  • Physiology

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