Potent stimulation of large-conductance Ca2+-activated K + channels by rottlerin, an inhibitor of protein kinase C-δ, in pituitary tumor (GH3) cells and in cortical neuronal (HCN-1A) cells

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

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Abstract

The effects of rottlerin, a known inhibitor of protein kinase C-δ activation, on ion currents were investigated in pituitary tumor (GH 3) cells. Rottlerin (0.3-100 μM) increased the amplitude of Ca2+-activated K+ current (IK(Ca)) in a concentration-dependent manner with an EC50 value of 1.7 μM. In intracellular perfusion with rottlerin (1 μM) or staurosporine (10 μM), phorbol 12-myristate 13-acetate-induced inhibition of IK(Ca) in these cells was abolished. In cell-attached mode, rottlerin applied on the extracellular side of the membrane caused activation of large-conductance Ca2+-activated K+ (BKCa) channels, and a further application of BAPTA-AM (10 μM) to the bath had no effect on rottlerin-stimulated channel activity. When cells were exposed to rottlerin, the activation curve of these channels was shifted to less positive potential with no change in the slope factor. Rottlerin increased BKCa-channel activity in outside-out patches. Its change in kinetic behavior of BK Ca channels is primarily due to an increase in mean open time. With the aid of minimal kinetic scheme, a quantitative description of rottlerin stimulation on BKCa channels in GH3 cells was also provided. Under current-clamp configuration, rottlerin (1 μM) decreased the firing of action potentials. IK(ca) elicited by simulated action potential waveforms was enhanced by this compound. In human cortical HCN-1A cells, rottlerin (1 μM) could also interact with the BKCa channel to stimulate IK(Ca). Therefore, rottlerin may directly activate BKCa channels in neurons or endocrine cells.

Original languageEnglish
Pages (from-to)655-666
Number of pages12
JournalJournal of Cellular Physiology
Volume210
Issue number3
DOIs
Publication statusPublished - 2007 Mar 1

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Calcium-Activated Potassium Channels
Pituitary Neoplasms
Protein Kinase C
Tumors
Chemical activation
Action Potentials
rottlerin
Large-Conductance Calcium-Activated Potassium Channels
Kinetics
Endocrine Cells
Staurosporine
Clamping devices
Baths
Neurons
Acetates
Perfusion
Cells

All Science Journal Classification (ASJC) codes

  • Clinical Biochemistry
  • Cell Biology
  • Physiology

Cite this

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title = "Potent stimulation of large-conductance Ca2+-activated K + channels by rottlerin, an inhibitor of protein kinase C-δ, in pituitary tumor (GH3) cells and in cortical neuronal (HCN-1A) cells",
abstract = "The effects of rottlerin, a known inhibitor of protein kinase C-δ activation, on ion currents were investigated in pituitary tumor (GH 3) cells. Rottlerin (0.3-100 μM) increased the amplitude of Ca2+-activated K+ current (IK(Ca)) in a concentration-dependent manner with an EC50 value of 1.7 μM. In intracellular perfusion with rottlerin (1 μM) or staurosporine (10 μM), phorbol 12-myristate 13-acetate-induced inhibition of IK(Ca) in these cells was abolished. In cell-attached mode, rottlerin applied on the extracellular side of the membrane caused activation of large-conductance Ca2+-activated K+ (BKCa) channels, and a further application of BAPTA-AM (10 μM) to the bath had no effect on rottlerin-stimulated channel activity. When cells were exposed to rottlerin, the activation curve of these channels was shifted to less positive potential with no change in the slope factor. Rottlerin increased BKCa-channel activity in outside-out patches. Its change in kinetic behavior of BK Ca channels is primarily due to an increase in mean open time. With the aid of minimal kinetic scheme, a quantitative description of rottlerin stimulation on BKCa channels in GH3 cells was also provided. Under current-clamp configuration, rottlerin (1 μM) decreased the firing of action potentials. IK(ca) elicited by simulated action potential waveforms was enhanced by this compound. In human cortical HCN-1A cells, rottlerin (1 μM) could also interact with the BKCa channel to stimulate IK(Ca). Therefore, rottlerin may directly activate BKCa channels in neurons or endocrine cells.",
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T1 - Potent stimulation of large-conductance Ca2+-activated K + channels by rottlerin, an inhibitor of protein kinase C-δ, in pituitary tumor (GH3) cells and in cortical neuronal (HCN-1A) cells

AU - Wu, Sheng-Nan

AU - Wang, Ya Jean

AU - Lin, Ming Wei

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N2 - The effects of rottlerin, a known inhibitor of protein kinase C-δ activation, on ion currents were investigated in pituitary tumor (GH 3) cells. Rottlerin (0.3-100 μM) increased the amplitude of Ca2+-activated K+ current (IK(Ca)) in a concentration-dependent manner with an EC50 value of 1.7 μM. In intracellular perfusion with rottlerin (1 μM) or staurosporine (10 μM), phorbol 12-myristate 13-acetate-induced inhibition of IK(Ca) in these cells was abolished. In cell-attached mode, rottlerin applied on the extracellular side of the membrane caused activation of large-conductance Ca2+-activated K+ (BKCa) channels, and a further application of BAPTA-AM (10 μM) to the bath had no effect on rottlerin-stimulated channel activity. When cells were exposed to rottlerin, the activation curve of these channels was shifted to less positive potential with no change in the slope factor. Rottlerin increased BKCa-channel activity in outside-out patches. Its change in kinetic behavior of BK Ca channels is primarily due to an increase in mean open time. With the aid of minimal kinetic scheme, a quantitative description of rottlerin stimulation on BKCa channels in GH3 cells was also provided. Under current-clamp configuration, rottlerin (1 μM) decreased the firing of action potentials. IK(ca) elicited by simulated action potential waveforms was enhanced by this compound. In human cortical HCN-1A cells, rottlerin (1 μM) could also interact with the BKCa channel to stimulate IK(Ca). Therefore, rottlerin may directly activate BKCa channels in neurons or endocrine cells.

AB - The effects of rottlerin, a known inhibitor of protein kinase C-δ activation, on ion currents were investigated in pituitary tumor (GH 3) cells. Rottlerin (0.3-100 μM) increased the amplitude of Ca2+-activated K+ current (IK(Ca)) in a concentration-dependent manner with an EC50 value of 1.7 μM. In intracellular perfusion with rottlerin (1 μM) or staurosporine (10 μM), phorbol 12-myristate 13-acetate-induced inhibition of IK(Ca) in these cells was abolished. In cell-attached mode, rottlerin applied on the extracellular side of the membrane caused activation of large-conductance Ca2+-activated K+ (BKCa) channels, and a further application of BAPTA-AM (10 μM) to the bath had no effect on rottlerin-stimulated channel activity. When cells were exposed to rottlerin, the activation curve of these channels was shifted to less positive potential with no change in the slope factor. Rottlerin increased BKCa-channel activity in outside-out patches. Its change in kinetic behavior of BK Ca channels is primarily due to an increase in mean open time. With the aid of minimal kinetic scheme, a quantitative description of rottlerin stimulation on BKCa channels in GH3 cells was also provided. Under current-clamp configuration, rottlerin (1 μM) decreased the firing of action potentials. IK(ca) elicited by simulated action potential waveforms was enhanced by this compound. In human cortical HCN-1A cells, rottlerin (1 μM) could also interact with the BKCa channel to stimulate IK(Ca). Therefore, rottlerin may directly activate BKCa channels in neurons or endocrine cells.

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