Novel role for the transient potential receptor melastatin 4 channel in guinea pig detrusor smooth muscle physiology

Amy C. Smith, Kiril L. Hristov, Qiuping Cheng, Wenkuan Xin, Shankar P. Parajuli, Scott Earley, John Malysz, Georgi Petkov

Research output: Contribution to journalArticle

20 Citations (Scopus)

Abstract

Members of the transient receptor potential (TRP) channel superfamily, including the Ca2+-activated monovalent cation-selective TRP melastatin 4 (TRPM4) channel, have been recently identified in the urinary bladder. However, their expression and function at the level of detrusor smooth muscle (DSM) remain largely unexplored. In this study, for the first time we investigated the role of TRPM4 channels in guinea pig DSM excitation-contraction coupling using a multidisciplinary approach encompassing protein detection, electrophysiology, live-cell Ca2+ imaging, DSM contractility, and 9-phenanthrol, a recently characterized selective inhibitor of the TRPM4 channel. Western blot and immunocytochemistry experiments demonstrated the expression of the TRPM4 channel in whole DSM tissue and freshly isolated DSM cells with specific localization on the plasma membrane. Perforated whole cell patch-clamp recordings and real-time Ca2+ imaging experiments with fura 2-AM, both using freshly isolated DSM cells, revealed that 9-phenanthrol (30 μM) significantly reduced the cation current and decreased intracellular Ca2+ levels. 9-Phenanthrol (0.1-30 μM) significantly inhibited spontaneous, 0.1 μM carbachol-induced, 20 mM KCl-induced, and nerve-evoked contractions in guinea pig DSM-isolated strips with IC50 values of 1-7 μM and 70-80% maximum inhibition. 9-Phenanthrol also reduced nerve-evoked contraction amplitude induced by continuous repetitive electrical field stimulation of 10-Hz frequency and shifted the frequency-response curve (0.5-50 Hz) relative to the control. Collectively, our data demonstrate the novel finding that TRPM4 channels are expressed in guinea pig DSM and reveal their critical role in the regulation of guinea pig DSM excitation-contraction coupling.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Cell Physiology
Volume304
Issue number5
DOIs
StatePublished - Mar 11 2013

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Smooth Muscle
Guinea Pigs
Excitation Contraction Coupling
Muscle Contraction
Smooth Muscle Myocytes
Transient Receptor Potential Channels
Monovalent Cations
Fura-2
Electrophysiology
Carbachol
Electric Stimulation
Inhibitory Concentration 50
Cations
Urinary Bladder
Western Blotting
Immunohistochemistry
Cell Membrane
Muscles
9-phenanthrol
Proteins

All Science Journal Classification (ASJC) codes

  • Cell Biology
  • Physiology

Cite this

Novel role for the transient potential receptor melastatin 4 channel in guinea pig detrusor smooth muscle physiology. / Smith, Amy C.; Hristov, Kiril L.; Cheng, Qiuping; Xin, Wenkuan; Parajuli, Shankar P.; Earley, Scott; Malysz, John; Petkov, Georgi.

In: American Journal of Physiology - Cell Physiology, Vol. 304, No. 5, 11.03.2013.

Research output: Contribution to journalArticle

Smith, Amy C. ; Hristov, Kiril L. ; Cheng, Qiuping ; Xin, Wenkuan ; Parajuli, Shankar P. ; Earley, Scott ; Malysz, John ; Petkov, Georgi. / Novel role for the transient potential receptor melastatin 4 channel in guinea pig detrusor smooth muscle physiology. In: American Journal of Physiology - Cell Physiology. 2013 ; Vol. 304, No. 5.
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