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Essential roles of ANO1 in mouse urethral smooth muscle contraction and urinary continence
Author(s) -
Feng Mei,
Liu Donghai,
Lu Ping,
Bellve Karl,
Lifshitz Lawrence M,
Fogarty Kevin,
ZhuGe Ronghua
Publication year - 2016
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.30.1_supplement.1013.6
Subject(s) - ryanodine receptor , nifedipine , endocrinology , medicine , contraction (grammar) , detrusor muscle , chemistry , muscle contraction , receptor , urinary bladder , calcium
Smooth muscle, the major cell type of urethra, generates sufficient intraurethral pressure to prevent voiding of urine from the bladder; its dysfunction contributes to stress urinary incontinence, a pathological disorder affecting up to 30% of women and causing physical discomfort and emotional distress. However, the cellular and molecular mechanisms underlying the contraction of urethral smooth muscle is not well understood. In the present study, we report that mouse urethral smooth muscle expresses type 2 ryanodine receptors, L‐type Ca 2+ channels, and the Ca 2+ ‐activated Cl − channel ANO1. In response to a load, mouse urethral strips relaxed and then developed a spontaneous tone. This tone was blocked by ryanodine receptor antagonist ryanodine, ANO1 antagonist benzbromarone, and L‐type Ca 2+ channel inhibitor nifedipine; this tone was absent in the urethral strips from smooth muscle specific ANO1 deletion mice. Ryanodine receptor agonist caffeine contracted mouse urethral strips dose‐dependently. This contraction was inhibited by ryanodine, nifedipine, benzbromarone and ANO1 deletion. Caffeine increased global [Ca 2+ ] i in isolated single urethral smooth muscle cells, and this increase in [Ca2+] i was inhibited by ryanodine, benzbromarone and nifedipine. In ANO1 deleted cells, caffeine caused less increase in [Ca 2+ ] i compared to the wild type cells, and this rise in [Ca 2+ ] i was resistant to benzbromarone and nifedipine. Caffeine induced Ca 2+ ‐activated Cl − currents in wild type cells, and failed to do so in the ANO1 deletion cells. The size of urine stains was greater while the number of stains was smaller in wild type mice than in ANO1 deletion mice, implying ANO1 deletion may impair urinary continence. We conclude that ANO1 is functionally coupled with ryanodine receptors and L‐type Ca 2+ channels, and this functional coupling is required for spontaneous tone and agonist‐induced contraction in urethra, and its disruption could lead to urinary incontinence. Support or Funding Information NIH NIDDK098586