Expression, localization, and regulation of  aquaporin-1 to -3 in rat urothelia

Spector, David A.; Wade, James B.; Dillow, Russell; Steplock, Deborah; Weinman, Edward J.

doi:10.1152/ajprenal.00136.2001

Cited by 79 publications

(107 citation statements)

References 26 publications

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“…Two AQP3 protein bands were detected. One of these appeared at ϳ27 kDa and represented the deglycosylated form of AQP3, whereas the other appeared at ϳ30 -40 kDa and represented a glycosylated form of AQP3 (32,33). This glycosylation is associated with the stability and intracellular translocation of AQP3 but has no influence on water permeability (1,8,35).…”

Section: Resultsmentioning

confidence: 99%

The laxative effect of bisacodyl is attributable to decreased aquaporin-3 expression in the colon induced by increased PGE₂secretion from macrophages

Ikarashi

Baba

Ushiki

et al. 2011

American Journal of Physiology-Gastrointestinal and Liver Physi

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Ikarashi N, Baba K, Ushiki T, Kon R, Mimura A, Toda T, Ishii M, Ochiai W, Sugiyama K. The laxative effect of bisacodyl is attributable to decreased aquaporin-3 expression in the colon induced by increased PGE 2 secretion from macrophages. Am J Physiol Gastrointest Liver Physiol 301: G887-G895, 2011. First published August 25, 2011; doi:10.1152/ajpgi.00286.2011.-The purpose of this study was to investigate the role of aquaporin3 (AQP3) in the colon in the laxative effect of bisacodyl. After oral administration of bisacodyl to rats, AQP3, macrophages, cyclooxygenase 2 (COX2), and prostaglandin E 2 (PGE2) were examined in the colon. The mechanism by which bisacodyl decreases the expression of AQP3 was examined using HT-29 and Raw264.7 cells. When diarrhea occurred, a significant increase in the expression of PGE 2 and a decrease in AQP3 expression were observed. Immunostaining showed COX2 expression only in macrophages. The PGE 2 concentration increased significantly 30 min after the addition of bisacodyl to Raw264.7 cells. Thirty minutes after PGE 2 addition to HT-29 cells, the AQP3 expression level decreased to 40% of the control. When pretreated with indomethacin, bisacodyl did not induce an increase in the colon PGE 2 level, a decrease in the AQP3 expression level, or diarrhea. The results suggest that bisacodyl may decrease the expression of AQP3 in the colon, which inhibits water transfer from the luminal to the vascular side and leads to a laxative effect. This study also showed that direct activation of colon macrophages by bisacodyl increases the secretion of PGE 2, which acts as a paracrine factor and decreases AQP3 expression in colon mucosal epithelial cells. aquaporin-3; prostaglandin E 2; bisacodyl; cyclooxygenase IN RECENT YEARS, IT HAS BECOME increasingly clear that aquaporins (AQPs), water channels, are involved in water transport in the intestinal tract (20). There are currently 13 known types of AQPs in humans, AQP0 through AQP12, which are expressed in a variety of tissues (15). Several AQPs are expressed in the intestinal tract, and at least the following eight types are known to exist there: AQP1, AQP2, AQP3, AQP4, AQP7, AQP8, AQP9, and AQP10 (5, 7, 17, 23). The main AQPs expressed in the colon are AQP1, AQP2, AQP3, AQP4, and AQP8 (5,16,23). Of these, extensive research has been conducted on AQP3, which is considered to play an important role in the colon, especially regarding water transfer (13, 34). We have found that the administration of the osmotic laxative magnesium sulfate (MgSO 4 ) to rats increases the expression of AQP3 in the colon, and an increase in the expression of AQP3 plays an essential role in the laxative effect of MgSO 4 (11,12).Bisacodyl is classified as a stimulant laxative and is widely used to treat constipation. Bisacodyl increases the production of prostaglandin E 2 (PGE 2 ) in intestinal epithelial cells and inhibits the activity of Na ϩ -K ϩ -ATPase, and, as a result, the osmotic pressure in the intestinal tract increases. It is believed that this increase in osmoti...

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Section: Resultsmentioning

confidence: 99%

The laxative effect of bisacodyl is attributable to decreased aquaporin-3 expression in the colon induced by increased PGE₂secretion from macrophages

Ikarashi

Baba

Ushiki

et al. 2011

American Journal of Physiology-Gastrointestinal and Liver Physi

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“…Bladders and ureters of anesthetized rats were fixed for immunolocalization by immersion of the tissues in 4% freshly prepared paraformaldehyde in PBS for 1 h. Tissues were then immersed in a cryprotectant solution of 10% EDTA in 0.1 M Tris buffer, pH 7.4, for 1 h at 4°C and frozen on dry ice. Antibodies were immunolocalized on 8-m frozen sections as previously described (30). Sections were incubated overnight at 4°C with primary antibodies diluted to 10 l/ml.…”

Section: Methodsmentioning

confidence: 99%

The ROMK potassium channel is present in mammalian urinary tract epithelia and muscle

Spector¹,

Yang²,

Klopouh³

et al. 2008

American Journal of Physiology-Renal Physiology

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There is increasing evidence that mammalian urinary tract epithelial cells utilize membrane channels and transporters to transport solutes across their apical (luminal) and basalateral membranes to modify solute concentrations in both cell and urine. This study investigates the expression, localization, and regulation of the ROMK (Kir 1.1) potassium channels in rat and dog ureter and bladder tissues. Immunoblots of homogenates of whole ureter, whole bladder, bladder epithelial cells, and bladder smooth muscle tissues in both rat and dog identified ϳ45-to 50-kDa bands characteristic of ROMK in all tissues. RT-PCR identified ROMK mRNA in these same tissues in both animal species. ROMK protein localized by immunocytochemistry was strongly expressed in the apical membranes of the large umbrella cells lining the bladder lumen and to a lesser extent in the cytoplasm of epithelial cells and smooth muscle cells in the rat bladder. ROMK protein and mRNA were also discovered in cardiac, striated, and smooth muscle in diverse organs. There was no difference in immunoblot expression of ROMK abundance in bladder homogenates (whole bladder, epithelial cell, or muscle cell) or ureteral homogenates between groups of rats fed high-or low-potassium diets. Although the functional role of ROMK in urinary tract epithelia and smooth muscle is unknown, ROMK may participate in the regulation of epithelial and smooth muscle cell volume and osmolality, in the dissipation of potassium leaked or diffused from urine across the epithelial cell apical membranes or tight junctions, and in net or bidirectional potassium transport across urinary tract epithelia. epithelial sodium channel; calponin MAMMALIAN URINARY TRACT EPITHELIA (urothelia) has long been held to serve solely as a storage conduct for urine made by the kidney and, in particular, to prevent modification of urine by inhibiting net flux of water and solutes across the epithelial cell luminal membrane (7). The barrier(s) preventing transepithelial flux of urine constituents have been shown to include: the lumenal membrane (containing unique uroplakin proteins) of the large ("umbrella") cells lining the urinary tract lumen (12), tight junctions adjoining the umbrella cells, and a glycosaminoglycans layer overlying and adjacent to the lumenal membrane (13, reviewed in Ref. 17). Evidence for the effectiveness of these barriers, which have been thought to be passive in nature and not to utilize or require membrane transporters, comes from Ussing chamber studies documenting very low urothelial permeability to water, ions, and nonelectrolytes and very high transepithelial cell resistance in stretched bladders and apical membrane endosomes obtained from rabbits under basal conditions (2, 24).However, although the permeabilities of urothelia for water and various urinary solutes may be low under basal conditions, urothelial permeabilities in animals subjected to dietary, physiological (e.g., water loading/water restricted), or other stress could be altered. Furthermore, urothelial cells are...

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“…Until now, data about AQPs in the mammalian urinary bladder have been limited. Spector et al [6] investigated the regulation of AQPs in the urothelium of rats following 24 hours of dehydration and water loading tests and reported the localization of AQP1, 2, and 3 in rat urothelium. They suggested that the AQPs in urothelium may play a role in regulating epithelial cell volume and osmolarity.…”

Section: Introductionmentioning

confidence: 99%

The Expression of AQP1 and eNOS in Menopausal Rat Urinary Bladder

et al. 2010

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Purpose: Aquaporins (AQPs) have been reported to be expressed in rat and human urothelium. Nitric oxide (NO) is thought to play an important role in the bladder overactivity related to menopause. The purpose of this study was to investigate the effect of hormonal alteration on the expression of AQP1 and eNOS in menopausal rat urinary bladder. Materials and Methods: Female Sprague-Dawley rats (230-240 g, N=30) were divided into three groups: control (N=10), bilateral ovariectomy (Ovx, N=10), and bilateral ovariectomy followed by subcutaneous injections of 17β -estradiol (50 mg/kg/day, Ovx+Est, N=10). After 4 weeks, urodynamic studies measuring the contraction interval and contraction pressure were done. The expression and cellular localization of AQP1 and eNOS were determined by performing Western blotting and immunohistochemistry on the rat urinary bladder. Results: The approximate contraction interval (min) was significantly decreased in the Ovx group (3.9±0.25) compared to the control group (6.7±0.15), and was increased after estrogen treatment (9.7±0.22) (p<0.05). The AQP1 and eNOS immunoreactivities were localized in the same areas: capillaries, arterioles, and venules of the lamina propria. The protein expression of AQP1 was not changed significantly, whereas eNOS expression was significantly decreased in the Ovx group and restored to the control value in the Ovx+Est group. Conclusions: This study showed that ovariectomy causes a significant change in e-NOS expression without a change in AQP1 in menopausal rat urinary bladder. This may imply that e-NOS has a functional role in the bladder overactivity that occurs in association with menopause.

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Expression, localization, and regulation of aquaporin-1 to -3 in rat urothelia

Cited by 79 publications

References 26 publications

The laxative effect of bisacodyl is attributable to decreased aquaporin-3 expression in the colon induced by increased PGE₂secretion from macrophages

The laxative effect of bisacodyl is attributable to decreased aquaporin-3 expression in the colon induced by increased PGE₂secretion from macrophages

The ROMK potassium channel is present in mammalian urinary tract epithelia and muscle

The Expression of AQP1 and eNOS in Menopausal Rat Urinary Bladder

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Expression, localization, and regulation of aquaporin-1 to -3 in rat urothelia

Cited by 79 publications

References 26 publications

The laxative effect of bisacodyl is attributable to decreased aquaporin-3 expression in the colon induced by increased PGE2secretion from macrophages

The laxative effect of bisacodyl is attributable to decreased aquaporin-3 expression in the colon induced by increased PGE2secretion from macrophages

The ROMK potassium channel is present in mammalian urinary tract epithelia and muscle

The Expression of AQP1 and eNOS in Menopausal Rat Urinary Bladder

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The laxative effect of bisacodyl is attributable to decreased aquaporin-3 expression in the colon induced by increased PGE₂secretion from macrophages

The laxative effect of bisacodyl is attributable to decreased aquaporin-3 expression in the colon induced by increased PGE₂secretion from macrophages