Large-conductance calcium-activated potassium channel activity, as determined by whole-cell patch clamp recording, is decreased in urinary bladder smooth muscle cells from male rats with partial urethral obstruction.

Memduh Aydin, Hong Zhan Wang, Xinhua Zhang, Rowena Chua, Keith Downing, Arnold Melman, Michael E. DiSanto

Research output: Contribution to journalArticle

14 Citations (Scopus)

Abstract

To examine the effect of partial urethral obstruction (PUO) on bladder smooth muscle outward potassium current and the contribution of the large-conductance calcium-activated potassium (Maxi-K, BKCa) channel to this activity in smooth muscle cells isolated from bladders of sham-operated and PUO male rats using whole-cell patch clamp recording techniques. To determine the effect of PUO on the expression of the Maxi-K channel α and β1 subunits and in vitro detrusor contractility. Twenty adult male Sprague-Dawley rats were divided equally into two groups and subjected to surgical ligation of the urethra (PUO) or sham surgery (SHAM). After 2 weeks, the detrusors from PUO and SHAM rats were used for molecular analyses (mRNA and protein quantification of Maxi-K subunits) or organ bath contractility studies, or myocytes were isolated for conventional whole-cell patch clamp analyses. PUO increased bladder mass 2.5-fold and detrusor strips exhibited a more tonic-type contraction and increased contractility compared with controls (SHAM). Iberiotoxin (300 nM) sensitive Maxi-K channel current comprised about 40% of the outward whole-cell current in SHAM bladders but only about 8% in PUO bladders. Expression of the α subunit of the Maxi-K channel was significantly decreased ~40% while the expression of the β1 subunit was increased ~2-fold at the mRNA level. The increase in β1 expression was confirmed by Western blotting. Our findings show that obstruction of the rat bladder is associated with decreased Maxi-K channel activity of bladder smooth muscle cells, determined via direct current measurement. Increased expression of the β1 subunit points to a compensatory reaction to decreased Maxi-K channel activity. Maxi-K channel openers or gene therapy may therefore provide therapeutic benefit for the overactive bladder.

Original languageEnglish (US)
JournalBJU International
Volume110
Issue number8 Pt B
StatePublished - 2012
Externally publishedYes

Fingerprint

Urethral Obstruction
Large-Conductance Calcium-Activated Potassium Channels
Smooth Muscle Myocytes
Urinary Bladder
Potassium
Overactive Urinary Bladder
Messenger RNA
Patch-Clamp Techniques
Urethra
Baths
Genetic Therapy
Muscle Cells
Ligation
Smooth Muscle
Sprague Dawley Rats
Western Blotting
Calcium
salicylhydroxamic acid

ASJC Scopus subject areas

  • Urology

Cite this

Large-conductance calcium-activated potassium channel activity, as determined by whole-cell patch clamp recording, is decreased in urinary bladder smooth muscle cells from male rats with partial urethral obstruction. / Aydin, Memduh; Wang, Hong Zhan; Zhang, Xinhua; Chua, Rowena; Downing, Keith; Melman, Arnold; DiSanto, Michael E.

In: BJU International, Vol. 110, No. 8 Pt B, 2012.

Research output: Contribution to journalArticle

Aydin, Memduh ; Wang, Hong Zhan ; Zhang, Xinhua ; Chua, Rowena ; Downing, Keith ; Melman, Arnold ; DiSanto, Michael E. / Large-conductance calcium-activated potassium channel activity, as determined by whole-cell patch clamp recording, is decreased in urinary bladder smooth muscle cells from male rats with partial urethral obstruction. In: BJU International. 2012 ; Vol. 110, No. 8 Pt B.
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AU - Zhang, Xinhua

AU - Chua, Rowena

AU - Downing, Keith

AU - Melman, Arnold

AU - DiSanto, Michael E.

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