Large-conductance voltage- and Ca2+-activated K+ channel regulation by protein kinase C in guinea pig urinary bladder smooth muscle

Kiril L. Hristov, Amy C. Smith, Shankar P. Parajuli, John Malysz, Georgi Petkov

Research output: Contribution to journalArticle

16 Citations (Scopus)

Abstract

Large-conductance voltage- and Ca2+-activated K+ (BK channels are critical regulators of detrusor smooth muscle (DSM excitability and contractility. PKC modulates the contraction of DSM and BK channel activity in non-DSM cells; however, the cellular mechanism regulating the PKC-BK channel interaction in DSM remains unknown. We provide a novel mechanistic insight into BK channel regulation by PKC in DSM. We used patch-clamp electrophysiology, live-cell Ca2+ imaging, and functional studies of DSM contractility to elucidate BK channel regulation by PKC at cellular and tissue levels. Voltage-clamp experiments showed that pharmacological activation of PKC with PMA inhibited the spontaneous transient BK currents in native freshly isolated guinea pig DSM cells. Current-clamp recordings revealed that PMA significantly depolarized DSM membrane potential and inhibited the spontaneous transient hyperpolarizations in DSM cells. The PMA inhibitory effects on DSM membrane potential were completely abolished by the selective BK channel inhibitor paxilline. Activation of PKC with PMA did not affect the amplitude of the voltage-step-induced whole cell steady-state BK current or the single BK channel open probability (recorded in cell-attached mode upon inhibition of all major Ca2+ sources for BK channel activation with thapsigargin, ryanodine, and nifedipine. PKC activation with PMA elevated intracellular Ca2+ levels in DSM cells and increased spontaneous phasic and nerve-evoked contractions of DSM isolated strips. Our results support the concept that PKC activation leads to a reduction of BK channel activity in DSM via a Ca2+-dependent mechanism, thus increasing DSM contractility.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Cell Physiology
Volume306
Issue number5
DOIs
StatePublished - Mar 1 2014
Externally publishedYes

Fingerprint

Large-Conductance Calcium-Activated Potassium Channels
Calcium-Activated Potassium Channels
Protein Kinase C
Smooth Muscle
Guinea Pigs
Urinary Bladder
Membrane Potentials
Ryanodine
Thapsigargin
Electrophysiology
Nifedipine
Pharmacology

All Science Journal Classification (ASJC) codes

  • Cell Biology
  • Physiology
  • Medicine(all)

Cite this

Large-conductance voltage- and Ca2+-activated K+ channel regulation by protein kinase C in guinea pig urinary bladder smooth muscle. / Hristov, Kiril L.; Smith, Amy C.; Parajuli, Shankar P.; Malysz, John; Petkov, Georgi.

In: American Journal of Physiology - Cell Physiology, Vol. 306, No. 5, 01.03.2014.

Research output: Contribution to journalArticle

@article{0a56b5a56dd54f148ea7f36a5441afec,
title = "Large-conductance voltage- and Ca2+-activated K+ channel regulation by protein kinase C in guinea pig urinary bladder smooth muscle",
abstract = "Large-conductance voltage- and Ca2+-activated K+ (BK channels are critical regulators of detrusor smooth muscle (DSM excitability and contractility. PKC modulates the contraction of DSM and BK channel activity in non-DSM cells; however, the cellular mechanism regulating the PKC-BK channel interaction in DSM remains unknown. We provide a novel mechanistic insight into BK channel regulation by PKC in DSM. We used patch-clamp electrophysiology, live-cell Ca2+ imaging, and functional studies of DSM contractility to elucidate BK channel regulation by PKC at cellular and tissue levels. Voltage-clamp experiments showed that pharmacological activation of PKC with PMA inhibited the spontaneous transient BK currents in native freshly isolated guinea pig DSM cells. Current-clamp recordings revealed that PMA significantly depolarized DSM membrane potential and inhibited the spontaneous transient hyperpolarizations in DSM cells. The PMA inhibitory effects on DSM membrane potential were completely abolished by the selective BK channel inhibitor paxilline. Activation of PKC with PMA did not affect the amplitude of the voltage-step-induced whole cell steady-state BK current or the single BK channel open probability (recorded in cell-attached mode upon inhibition of all major Ca2+ sources for BK channel activation with thapsigargin, ryanodine, and nifedipine. PKC activation with PMA elevated intracellular Ca2+ levels in DSM cells and increased spontaneous phasic and nerve-evoked contractions of DSM isolated strips. Our results support the concept that PKC activation leads to a reduction of BK channel activity in DSM via a Ca2+-dependent mechanism, thus increasing DSM contractility.",
author = "Hristov, {Kiril L.} and Smith, {Amy C.} and Parajuli, {Shankar P.} and John Malysz and Georgi Petkov",
year = "2014",
month = "3",
day = "1",
doi = "10.1152/ajpcell.00325.2013",
language = "English (US)",
volume = "306",
journal = "American Journal of Physiology",
issn = "0363-6143",
publisher = "American Physiological Society",
number = "5",

}

TY - JOUR

T1 - Large-conductance voltage- and Ca2+-activated K+ channel regulation by protein kinase C in guinea pig urinary bladder smooth muscle

AU - Hristov, Kiril L.

AU - Smith, Amy C.

AU - Parajuli, Shankar P.

AU - Malysz, John

AU - Petkov, Georgi

PY - 2014/3/1

Y1 - 2014/3/1

N2 - Large-conductance voltage- and Ca2+-activated K+ (BK channels are critical regulators of detrusor smooth muscle (DSM excitability and contractility. PKC modulates the contraction of DSM and BK channel activity in non-DSM cells; however, the cellular mechanism regulating the PKC-BK channel interaction in DSM remains unknown. We provide a novel mechanistic insight into BK channel regulation by PKC in DSM. We used patch-clamp electrophysiology, live-cell Ca2+ imaging, and functional studies of DSM contractility to elucidate BK channel regulation by PKC at cellular and tissue levels. Voltage-clamp experiments showed that pharmacological activation of PKC with PMA inhibited the spontaneous transient BK currents in native freshly isolated guinea pig DSM cells. Current-clamp recordings revealed that PMA significantly depolarized DSM membrane potential and inhibited the spontaneous transient hyperpolarizations in DSM cells. The PMA inhibitory effects on DSM membrane potential were completely abolished by the selective BK channel inhibitor paxilline. Activation of PKC with PMA did not affect the amplitude of the voltage-step-induced whole cell steady-state BK current or the single BK channel open probability (recorded in cell-attached mode upon inhibition of all major Ca2+ sources for BK channel activation with thapsigargin, ryanodine, and nifedipine. PKC activation with PMA elevated intracellular Ca2+ levels in DSM cells and increased spontaneous phasic and nerve-evoked contractions of DSM isolated strips. Our results support the concept that PKC activation leads to a reduction of BK channel activity in DSM via a Ca2+-dependent mechanism, thus increasing DSM contractility.

AB - Large-conductance voltage- and Ca2+-activated K+ (BK channels are critical regulators of detrusor smooth muscle (DSM excitability and contractility. PKC modulates the contraction of DSM and BK channel activity in non-DSM cells; however, the cellular mechanism regulating the PKC-BK channel interaction in DSM remains unknown. We provide a novel mechanistic insight into BK channel regulation by PKC in DSM. We used patch-clamp electrophysiology, live-cell Ca2+ imaging, and functional studies of DSM contractility to elucidate BK channel regulation by PKC at cellular and tissue levels. Voltage-clamp experiments showed that pharmacological activation of PKC with PMA inhibited the spontaneous transient BK currents in native freshly isolated guinea pig DSM cells. Current-clamp recordings revealed that PMA significantly depolarized DSM membrane potential and inhibited the spontaneous transient hyperpolarizations in DSM cells. The PMA inhibitory effects on DSM membrane potential were completely abolished by the selective BK channel inhibitor paxilline. Activation of PKC with PMA did not affect the amplitude of the voltage-step-induced whole cell steady-state BK current or the single BK channel open probability (recorded in cell-attached mode upon inhibition of all major Ca2+ sources for BK channel activation with thapsigargin, ryanodine, and nifedipine. PKC activation with PMA elevated intracellular Ca2+ levels in DSM cells and increased spontaneous phasic and nerve-evoked contractions of DSM isolated strips. Our results support the concept that PKC activation leads to a reduction of BK channel activity in DSM via a Ca2+-dependent mechanism, thus increasing DSM contractility.

UR - http://www.scopus.com/inward/record.url?scp=84899448198&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84899448198&partnerID=8YFLogxK

U2 - 10.1152/ajpcell.00325.2013

DO - 10.1152/ajpcell.00325.2013

M3 - Article

VL - 306

JO - American Journal of Physiology

JF - American Journal of Physiology

SN - 0363-6143

IS - 5

ER -