J Korean Med Sci.  2016 Feb;31(2):280-285. 10.3346/jkms.2016.31.2.280.

Impaired Na+/K+-ATPase Function in Patients with Interstitial Cystitis/Painful Bladder Syndrome

• Lee JD
• Yang WK
• Lee MH

• KMID: 2360054
• DOI: http://doi.org/10.3346/jkms.2016.31.2.280

Abstract

Na+/K+-ATPase (NKA) is abundantly expressed in the basolateral membrane of epithelial cells, which is necessary for tight junction formation. The tight junction is an urothelial barrier between urine and the underlying bladder. Impairment of tight junctions allows migration of urinary solutes in patients with interstitial cystitis/painful bladder syndrome (IC/PBS). We evaluated NKA expression and activity in bladder samples from patients with IC/PBS. The study group consisted of 85 patients with IC/PBS, and the control group consisted of 20 volunteers. Bladder biopsies were taken from both groups. We determined the expression and distribution of NKA using NKA activity assays, immunoblotting, immunohistochemical staining, and immunofluorescent staining. The protein levels and activity of NKA in the study group were significantly lower than the control group (1.08 ± 0.06 vs. 2.39 ± 0.29 and 0.60 ± 0.04 vs. 1.81 ± 0.18 micromol ADP/mg protein/hour, respectively; P < 0.05). Additionally, immunofluorescent staining for detection of CK7, a marker of the bladder urothelium, predominantly colocalized with NKA in patients in the study group. Our results demonstrated the expression and activity of NKA were decreased in bladder biopsies of patients with IC/PBS. These findings suggest that NKA function is impaired in the bladders from patients with IC/PBS.

Keyword

Na+/K+-ATPase; Bladder Urothelium; Interstitial Cystitis; Painful Bladder Syndrome

MeSH Terms

Adult
Cystitis, Interstitial/*diagnosis/metabolism
Female
Fluorescent Antibody Technique
Humans
Keratin-7/metabolism
Male
Microscopy, Fluorescence
Middle Aged
Sodium-Potassium-Exchanging ATPase/*metabolism
Urinary Bladder/metabolism/pathology
Urothelium/metabolism/pathology
Keratin-7
Sodium-Potassium-Exchanging ATPase

Figure

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  Fig. 1 Representative immunoblot and relative intensities of the Na+/K+-ATPase (NKA) α-subunit in patients in the study and control groups. Actin was used as the loading control. Values are the mean ± SE. The asterisk indicates a significant difference compared with the control group.

• 

  Fig. 2 Na+/K+-ATPase (NKA) activity in the study and control groups. Values are the mean ± SE. The asterisk indicates a significant difference compared with the control group.

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  Fig. 3 Representative tissue sections from patients in the study (A, B) and control (C, D) groups after negative control (A, C) or Na+/K+-ATPase (NKA) immunostaining (B, D). Magnification: 600 ×. The black double-headed arrow indicates the urothelium. Scale bar = 20 µm.

• 

  Fig. 4 Representative tissue sections from patients in the study group after multiple IF staining for Na+/K+-ATPase (NKA, green; A), CK7 (uroepithelial marker, red; B) and merged image (C). The arrow indicates the urothelium. Scale bar = 20 µm.

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