Nongenomic modulation of the large conductance voltage- and Ca2+-activated K+ channels by estrogen

A novel regulatory mechanism in human detrusor smooth muscle

Kiril L. Hristov, Shankar P. Parajuli, Aaron Provence, Eric S. Rovner, Georgi Petkov

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

Estrogens have an important role in regulating detrusor smooth muscle (DSM) function. However, the underlying molecular and cellular mechanisms by which estrogens control human DSM excitability and contractility are not well known. Here, we used human DSM specimens from open bladder surgeries on 27 patients to elucidate the mechanism by which 17β-estradiol regulates large conductance voltage- and Ca2+-activated K+ (BK) channels, the most prominent K+ channels in human DSM. We employed single BK channel recordings on inside-out excised membrane patches, perforated whole-cell patch-clamp on freshly isolated DSM cells, and isometric tension recordings on DSM-isolated strips to investigate the mechanism by which 17β-estradiol activates BK channels. 17β-Estradiol (100 nmol/L) rapidly increased depolarization-induced whole-cell K+ currents in DSM cells. The 17β-estradiol stimulatory effects on whole-cell BK currents were completely abolished by the selective BK channel inhibitor paxilline (1 μmol/L), clearly indicating that 17β-estradiol specifically activates BK channels. 17β-Estradiol also increased the frequency of ryanodine receptor-mediated transient BK currents. Single BK channel recordings showed that 17β-estradiol (100 nmol/L) significantly increased the BK channel open probability of inside-out excised membrane patches, revealing that 17β-estradiol activates BK channels directly. 17β-Estradiol reduced spontaneous phasic contractions of human DSM-isolated strips in a concentration-dependent manner (100 nmol/L-1 μmol/L), and this effect was blocked by paxilline (1 μmol/L). 17β-Estradiol (100 nmol/L) also reduced nerve-evoked contractions of human DSM-isolated strips. Collectively, our results reveal that 17β-estradiol plays a critical role in regulating human DSM function through a direct nongenomic activation of BK channels.

Original languageEnglish (US)
Article numbere13351
JournalPhysiological Reports
Volume5
Issue number14
DOIs
StatePublished - Jul 1 2017

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Calcium-Activated Potassium Channels
Large-Conductance Calcium-Activated Potassium Channels
Smooth Muscle
Estradiol
Estrogens
Smooth Muscle Myocytes
Ryanodine Receptor Calcium Release Channel
Membranes
Urinary Bladder

All Science Journal Classification (ASJC) codes

  • Physiology
  • Physiology (medical)

Cite this

Nongenomic modulation of the large conductance voltage- and Ca2+-activated K+ channels by estrogen : A novel regulatory mechanism in human detrusor smooth muscle. / Hristov, Kiril L.; Parajuli, Shankar P.; Provence, Aaron; Rovner, Eric S.; Petkov, Georgi.

In: Physiological Reports, Vol. 5, No. 14, e13351, 01.07.2017.

Research output: Contribution to journalArticle

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abstract = "Estrogens have an important role in regulating detrusor smooth muscle (DSM) function. However, the underlying molecular and cellular mechanisms by which estrogens control human DSM excitability and contractility are not well known. Here, we used human DSM specimens from open bladder surgeries on 27 patients to elucidate the mechanism by which 17β-estradiol regulates large conductance voltage- and Ca2+-activated K+ (BK) channels, the most prominent K+ channels in human DSM. We employed single BK channel recordings on inside-out excised membrane patches, perforated whole-cell patch-clamp on freshly isolated DSM cells, and isometric tension recordings on DSM-isolated strips to investigate the mechanism by which 17β-estradiol activates BK channels. 17β-Estradiol (100 nmol/L) rapidly increased depolarization-induced whole-cell K+ currents in DSM cells. The 17β-estradiol stimulatory effects on whole-cell BK currents were completely abolished by the selective BK channel inhibitor paxilline (1 μmol/L), clearly indicating that 17β-estradiol specifically activates BK channels. 17β-Estradiol also increased the frequency of ryanodine receptor-mediated transient BK currents. Single BK channel recordings showed that 17β-estradiol (100 nmol/L) significantly increased the BK channel open probability of inside-out excised membrane patches, revealing that 17β-estradiol activates BK channels directly. 17β-Estradiol reduced spontaneous phasic contractions of human DSM-isolated strips in a concentration-dependent manner (100 nmol/L-1 μmol/L), and this effect was blocked by paxilline (1 μmol/L). 17β-Estradiol (100 nmol/L) also reduced nerve-evoked contractions of human DSM-isolated strips. Collectively, our results reveal that 17β-estradiol plays a critical role in regulating human DSM function through a direct nongenomic activation of BK channels.",
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