Korean J Urol.  2010 Apr;51(4):281-286.

Changes in Aquaporin 1 Expression in Rat Urinary Bladder after Partial Bladder Outlet Obstruction: Preliminary Report

• Kim SO
• Song SH
• Ahn K
• Kwon D
• Park K
• Ryu SB

Abstract

PURPOSE
Aquaporins (AQPs) are membrane proteins that facilitate water movement across biological membranes. AQPs are also called water channels, and they have recently been reported to be expressed in rat and human urothelium. The purposes of this study were to investigate the effect of bladder outlet obstruction (BOO) on the rat urothelium and AQP1 expression in rat urothelium. MATERIALS AND METHODS: Female Sprague-Dawley rats (230-240 g each, n=20) were divided into 2 groups: the sham group (the Con group, n=10) and the partial BOO group (the BOO group, n=10). The BOO group underwent a partial BOO. The expression and cellular localization of AQP1 were determined by performing Western blotting and immunohistochemistry on the rat urinary bladder. RESULTS: AQP1 immunoreactivity in both the control and the BOO groups was localized in the capillaries, arterioles, and venules of the lamina propria of the urinary bladder. The protein expression of AQP1 was significantly increased in the BOO group. CONCLUSIONS: This study showed that BOO causes a significant increase in the expression of AQP1. This may imply that AQP1 has a functional role in the detrusor instability that occurs in association with BOO.

Keyword

Aquaporins; Urinary bladder; Urethral obstruction; Rats

MeSH Terms

Animals
Aquaporin 1
Aquaporins
Arterioles
Blotting, Western
Capillaries
Female
Humans
Immunohistochemistry
Membrane Proteins
Membranes
Mucous Membrane
Rats
Rats, Sprague-Dawley
Salicylamides
Urethral Obstruction
Urinary Bladder
Urinary Bladder Neck Obstruction
Urothelium
Venules
Water Movements
Aquaporin 1
Aquaporins
Membrane Proteins
Salicylamides

Figure

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  FIG. 1 Hematoxylin and eosin (H&E) staining of the urinary bladder tissue in the rats of the Con group and the BOO group. A significant increase in the smooth muscle content and the submucosal tissues along with relative epithelial thinning were noted in the BOO group compared with the control group. The horizontal scale bar at the bottom of each figure indicates the magnification power. Con: control, BOO: bladder outlet obstruction.

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  FIG. 2 Immunohistochemistry for aquaporin 1 (AQP1) in the rat urinary bladder tissue of the Con group and the BOO group. AQPs are stained brown via immunolabeling. AQP1 was mainly expressed in the capillaries, arterioles, and venules. The expression of AQP1 was increased in the BOO group. The horizontal scale bar at the bottom of each figure indicates the magnification power. Con: control, BOO: bladder outlet obstruction.

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  FIG. 3 Immunofluorescence labeling for aquaporin 1 (AQP1) in the rat urinary bladder. AQP1 expression (green) was noted throughout the capillaries, venules, and vascular smooth muscle. The expression of AQP1 was increased in the BOO group. The horizontal scale bar at the bottom left of each figure indicates the magnification power. Con: control, BOO: bladder outlet obstruction.

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  FIG. 4 Immunoblotting for aquaporin 1 (AQP1) in the rat urinary bladder. The anti-AQP antibodies recognize the 27 to 29 kDa bands that correspond to glycosylated AQPs. Anti-GAPDH antibody recognizes the 42 kDa band. The expression of AQP1 protein was significantly increased in the BOO group. The lower panels denote the means±SEs of the 5 experiments for each condition, as determined by the densitometry relative to GAPDH. Con: control, BOO: bladder outlet obstruction, a: p<0.05.

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