Details
| Original language | English |
|---|---|
| Pages (from-to) | 36-41 |
| Number of pages | 6 |
| Journal | Pflugers Archiv European Journal of Physiology |
| Volume | 446 |
| Issue number | 1 |
| Publication status | Published - Apr 2003 |
Abstract
The effect of calmodulin (CaM) antagonists W7, trifluoperazine (TFP) and a calmodulin inhibitory peptide on gap junction coupling in isolated Hensen cells of the organ of Corti was analysed by the double whole-cell patch-clamp technique. Addition of the conventional antagonists W7 and TFP in the micromolar range caused a rapid decrease of gap junction conductance after a delay of a few minutes in a dose-dependent manner. Fluorescence spectroscopy of cytoplasmic free calcium concentration ([Ca(2+)](i)) by Fura-2 showed no significant change of [Ca(2+)](i) by W7. Chelation of [Ca(2+)](i) by 10 mM BAPTA or use of nominally Ca(2+)-free external bath did not suppress the W7-induced gap junction uncoupling. The results suggest that W7 and TFP induce gap junction uncoupling at unchanged global [Ca(2+)](i) in Hensen cells. To obtain additional evidence for an involvement of CaM in regulating gap junction conductance a calmodulin inhibitory peptide, the MLCK peptide (250 nM), was added to the standard pipette solution. Again gap junction uncoupling was observed, but on a significantly slower time scale. This is the first study of an effect of calmodulin antagonists on gap junction coupling in isolated Hensen cells. The question whether the effect of calmodulin inhibitors is specific and involves CaM-dependent gating of gap junction coupling in Hensen cells is discussed.
Keywords
- Animals, Calcium/metabolism, Calcium-Calmodulin-Dependent Protein Kinases/antagonists & inhibitors, Calmodulin/antagonists & inhibitors, Cells, Cultured, Electric Conductivity, Gap Junctions/drug effects, Guinea Pigs, Membrane Potentials/physiology, Organ of Corti/cytology, Patch-Clamp Techniques, Peptides/pharmacology, Spectrometry, Fluorescence, Sulfonamides/pharmacology, Trifluoperazine/pharmacology
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In: Pflugers Archiv European Journal of Physiology, Vol. 446, No. 1, 04.2003, p. 36-41.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Calmodulin antagonists suppress gap junction coupling in isolated Hensen cells of the guinea pig cochlea
AU - Blödow, Alexander
AU - Ngezahayo, Anaclet
AU - Ernst, Arne
AU - Kolb, Hans-Albert
PY - 2003/4
Y1 - 2003/4
N2 - The effect of calmodulin (CaM) antagonists W7, trifluoperazine (TFP) and a calmodulin inhibitory peptide on gap junction coupling in isolated Hensen cells of the organ of Corti was analysed by the double whole-cell patch-clamp technique. Addition of the conventional antagonists W7 and TFP in the micromolar range caused a rapid decrease of gap junction conductance after a delay of a few minutes in a dose-dependent manner. Fluorescence spectroscopy of cytoplasmic free calcium concentration ([Ca(2+)](i)) by Fura-2 showed no significant change of [Ca(2+)](i) by W7. Chelation of [Ca(2+)](i) by 10 mM BAPTA or use of nominally Ca(2+)-free external bath did not suppress the W7-induced gap junction uncoupling. The results suggest that W7 and TFP induce gap junction uncoupling at unchanged global [Ca(2+)](i) in Hensen cells. To obtain additional evidence for an involvement of CaM in regulating gap junction conductance a calmodulin inhibitory peptide, the MLCK peptide (250 nM), was added to the standard pipette solution. Again gap junction uncoupling was observed, but on a significantly slower time scale. This is the first study of an effect of calmodulin antagonists on gap junction coupling in isolated Hensen cells. The question whether the effect of calmodulin inhibitors is specific and involves CaM-dependent gating of gap junction coupling in Hensen cells is discussed.
AB - The effect of calmodulin (CaM) antagonists W7, trifluoperazine (TFP) and a calmodulin inhibitory peptide on gap junction coupling in isolated Hensen cells of the organ of Corti was analysed by the double whole-cell patch-clamp technique. Addition of the conventional antagonists W7 and TFP in the micromolar range caused a rapid decrease of gap junction conductance after a delay of a few minutes in a dose-dependent manner. Fluorescence spectroscopy of cytoplasmic free calcium concentration ([Ca(2+)](i)) by Fura-2 showed no significant change of [Ca(2+)](i) by W7. Chelation of [Ca(2+)](i) by 10 mM BAPTA or use of nominally Ca(2+)-free external bath did not suppress the W7-induced gap junction uncoupling. The results suggest that W7 and TFP induce gap junction uncoupling at unchanged global [Ca(2+)](i) in Hensen cells. To obtain additional evidence for an involvement of CaM in regulating gap junction conductance a calmodulin inhibitory peptide, the MLCK peptide (250 nM), was added to the standard pipette solution. Again gap junction uncoupling was observed, but on a significantly slower time scale. This is the first study of an effect of calmodulin antagonists on gap junction coupling in isolated Hensen cells. The question whether the effect of calmodulin inhibitors is specific and involves CaM-dependent gating of gap junction coupling in Hensen cells is discussed.
KW - Animals
KW - Calcium/metabolism
KW - Calcium-Calmodulin-Dependent Protein Kinases/antagonists & inhibitors
KW - Calmodulin/antagonists & inhibitors
KW - Cells, Cultured
KW - Electric Conductivity
KW - Gap Junctions/drug effects
KW - Guinea Pigs
KW - Membrane Potentials/physiology
KW - Organ of Corti/cytology
KW - Patch-Clamp Techniques
KW - Peptides/pharmacology
KW - Spectrometry, Fluorescence
KW - Sulfonamides/pharmacology
KW - Trifluoperazine/pharmacology
U2 - 10.1007/s00424-002-1004-9
DO - 10.1007/s00424-002-1004-9
M3 - Article
C2 - 12690460
VL - 446
SP - 36
EP - 41
JO - Pflugers Archiv European Journal of Physiology
JF - Pflugers Archiv European Journal of Physiology
SN - 0031-6768
IS - 1
ER -