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Function of BKCa channels is reduced in human vascular smooth muscle cells from Han Chinese patients with

Yan Yang1, Peng-Yun Li, Jun Cheng

  • 1Key Laboratory of Medical Electrophysiology, Ministry of Education of China, and the Institute of Cardiovascular Research, Luzhou Medical College, Luzhou, Sichuan, China.

Hypertension (Dallas, Tex. : 1979)
|December 13, 2012
PubMed

Insights

Large-conductance Ca(2+)- and voltage-activated K(+) (BK(Ca)) channels show impaired function in hypertensive patients. Reduced BK(Ca) channel activity, specifically the β1-subunit, contributes to dysfunctional artery relaxation in hypertension.

Area of Science:

  • Cardiovascular Physiology
  • Molecular Biology
  • Hypertension Research

Background:

  • Chronic hypertension is linked to impaired vascular relaxation and increased vascular tone.
  • The precise molecular mechanisms behind this vascular dysfunction in humans remain unclear.

Purpose of the Study:

  • To investigate the role of large-conductance Ca(2+)- and voltage-activated K(+) (BK(Ca)) channels in arterial relaxation dysfunction in Han Chinese patients with hypertension.
  • To examine the gene and protein expression of BK(Ca) channel subunits (α-subunit [KCa1.1] and β1-subunit [KCNMB1]) in vascular smooth muscle cells and mesenteric arteries.

Main Methods:

  • Utilized perforated patch clamp, inside-out single-channel, and macromembrane patch recording techniques.
  • Assessed whole-cell current, spontaneous transient outward current, open probability, and Ca(2+) sensitivity.
  • Employed reverse transcription polymerase chain reaction and Western blot analysis for gene and protein expression.

Main Results:

  • Vascular smooth muscle cells from hypertensive patients exhibited significantly decreased whole-cell current density, spontaneous transient outward current, and Ca(2+) sensitivity.
  • mRNA and protein levels of the KCNMB1 (β1-subunit) were reduced in arterial tissue from hypertensive patients, while KCa1.1 (α-subunit) levels were unchanged.
  • Single-channel open probability and slope conductance were not significantly different between groups.

Conclusions:

  • BK(Ca) channel function, including whole-cell current, spontaneous transient outward current, and Ca(2+) sensitivity, is reduced in human vascular smooth muscle cells from hypertensive patients.
  • This reduction is attributed to the downregulation of the BK(Ca) channel's β1-subunit (KCNMB1).
  • Downregulation of the β1-subunit of BK(Ca) channels may contribute to the impaired artery relaxation observed in Han Chinese patients with primary hypertension.

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