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Calcium-activated potassium channels contribute to human skeletal muscle microvascular endothelial dysfunction

Yuhong Liu1, Eric W Sellke, Jun Feng

  • 1Division of Cardiothoracic Surgery, Department of Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA.

Surgery
|July 29, 2008
PubMed

Insights

Cardiopulmonary bypass impairs human skeletal muscle microvascular function by reducing intermediate and small conductance calcium-activated potassium channel activity, particularly in the endothelium. This suggests a key role for these channels in CPB-associated dysfunction.

Area of Science:

  • Physiology
  • Cardiovascular Research
  • Vascular Biology

Background:

  • Investigating calcium-activated potassium (K(Ca)) channel function in human skeletal muscle microvascular responses during cardiopulmonary bypass (CPB).
  • Understanding microvascular dysfunction post-CPB is crucial for patient outcomes.

Purpose of the Study:

  • To determine the role of K(Ca) channel activity in human skeletal muscle microvascular function following CPB.
  • To differentiate the endothelial dependence of various K(Ca) channel subtypes.

Main Methods:

  • Human skeletal muscle arterioles were isolated pre- and post-CPB.
  • In vitro relaxation responses to K(Ca) channel activators (NS309 for IK/SK(Ca), NS1619 for BK(Ca)) and vasodilators (ADP, substance P, SNP) were assessed.
  • Effects of endothelial denudation on relaxation responses were evaluated.

Main Results:

  • Post-CPB, relaxation to IK/SK(Ca) channel activator NS309, ADP, and substance P was reduced.
  • Relaxation to BK(Ca) channel activator NS1619 and SNP remained unchanged post-CPB.
  • Endothelial denudation impaired NS309, ADP, and substance P-induced relaxation but not NS1619 or SNP-induced relaxation.

Conclusions:

  • IK/SK(Ca) channel-mediated relaxation is primarily endothelium-dependent in skeletal muscle arterioles.
  • BK(Ca) channel-mediated relaxation is largely independent of endothelial function.
  • CPB-associated microvascular dysfunction may stem from impaired endothelial IK/SK(Ca) channel function.
Abstract

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