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Calmodulin antagonists do not inhibit IK(Ca) channels of human erythrocytes.

Authors
  • Del Carlo, Barbara
  • Pellegrini, Monica
  • Pellegrino, Mario
Type
Published Article
Journal
Biochimica et Biophysica Acta
Publisher
Elsevier
Publication Date
Feb 01, 2002
Volume
1558
Issue
2
Pages
133–141
Identifiers
PMID: 11779563
Source
Medline
License
Unknown

Abstract

Patch-clamp recordings were performed to study the effects of three calmodulin (CaM) antagonists on the gating of intermediate calcium-activated K(+) channels (IK(Ca)) of human erythrocytes. In the cell-attached configuration, both opening frequency and open probability of IK(Ca) channels were not significantly different in control cells and in those incubated with calmidazolium, trifluoperazine or W7. IK(Ca) channels in excised membrane patches, were normally activated by the calcium bathing the cytoplasmic side in the presence of CaM antagonists, at calcium concentrations ranging from 10(-7) to 10(-3) M. The activity of IK(Ca) channels, which had been previously up-modulated by an endogenous cAMP-dependent protein kinase, was not inhibited when perfused with CaM antagonists. The results presented in this study demonstrate that calmodulin antagonists do not inhibit the activity of native IK(Ca) channels of human erythrocytes. These data are in accordance with findings on the cloned IK(Ca) indicating that calmodulin is constitutively associated with these channels.

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