Adenosine triphosphate (ATP) is a signaling molecule that regulates cellular processes. Based on previous studies of bladder function over the past decade, bladder ATP signaling was thought to have an essential role in the normal micturition reflex. In this study, we performed detailed analyses of bladder function in purinergic receptor-deficient mice using the automated voided stain on paper method and video-urodynamics. Unexpectedly, a lack of P2X2 or P2X3 receptors did not affect bladder function under normal physiological conditions, indicating that bladder ATP signaling is not essential for normal micturition reflex. In contrast, we found that lipopolysaccharide (LPS) induced markedly high levels of ATP release from the urothelium. In addition, LPS-induced rapid bladder hyperactivity was attenuated in P2X2−/− and P2X3−/− mice. Contrary to the previous interpretation, our present findings indicate that bladder ATP signaling has a fundamental role in the micturition reflex, especially in bladder dysfunction, under pathological conditions. Therefore, the bladder ATP signaling pathway might be a highly promising therapeutic target for functional bladder disorders. This study newly defines an authentic role for bladder ATP signaling in the micturition reflex.

Takezawa K, Kondo M, Kiuchi H, Soda T, Takao T, Miyagawa Y, Tsujimura A, Nonomura N, Shimada S. Combination of bladder ultrasonography and novel cystometry method in mice reveals rapid decrease in bladder capacity and compliance in LPS-induced cystitis. Am J Physiol Renal Physiol 307: F234 -F241, 2014. First published May 7, 2014 doi:10.1152/ajprenal.00043.2014.-Various animal models have been used in research into bladder dysfunction, and in vivo cystometry is a common method to analyze bladder function in animals. However, it is rather difficult to perform reliably in small animals. Transabdominal bladder ultrasonography combined with cystometry in urethane-anesthetized mice have revealed physical inhibition of bladder wall movement by a bladder catheter conventionally placed in the bladder apex. For reliable evaluation of mouse lower urinary tract function, we established a novel cystometry method in which a catheter was placed in the bladder anterior wall, in combination with bladder ultrasonography. This new method allowed the bladder to be well distended (i.e., larger maximum bladder capacity, lower pressure threshold, higher voided volume, and higher bladder compliance compared with conventional methods), which reflected more spontaneous voiding than conventional cystometry methods. We also demonstrated the usefulness of bladder ultrasonography for analysis of mouse bladder function, especially bladder dynamics, maximum bladder capacity, and post-voiding residual volume. We analyzed bladder functional changes in lipopolysaccharide (LPS)-induced cystitis by combining bladder ultrasonography and this new cystometry method. Bladder ultrasonography revealed a rapid decrease in bladder capacity, and cystometry showed a rapid decrease in voided volume due to intravesical LPS instillation. This new cystometry method also revealed a rapid decrease in bladder compliance caused by LPS instillation, which was not detectable by conventional methods. The combination of ultrasonography and the new cystometry method may become a powerful tool for analysis of mouse bladder function and could contribute to the development of new treatments for bladder dysfunction. bladder ultrasonography; cystometry; mouse; LPS; cystitis VARIOUS DISEASES CAUSE BLADDER dysfunction with lower urinary tract symptoms (11). Some diseases, such as overactive bladder, interstitial cystitis, and neurogenic bladder, lead to storage failure, and other diseases, such as underactive bladder and bladder neck construction, lead to voiding failure. Objective evaluation of bladder function is indispensable for accurate diagnosis and development of appropriate treatment strategy for these diseases. Bladder ultrasonography, which can evaluate postvoiding residual volume and bladder wall thickness, is noninvasive and the most common examination for bladder function (5). Cystometry, which can identify detrusor overactivity, low bladder compliance (BCP), and sensory urgency, is an invasive but gold standard examination for bladder function (8). Thus these ex...

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We herein report the case of a patient with a juxtaglomerular cell tumor (JCT). Dynamic enhanced computed tomography revealed a small nodule on the surface of the lower pole of the right kidney. Selective renal venous sampling showed an elevated level of plasma renin activity (PRA) in the right lower pole renal vein only. We performed right partial nephrectomy and diagnosed the patient with JCT. Making a diagnosis of JCT is often difficult due to the small size of the tumor and the lack of lateralization of the PRA on renal venous sampling. This case highlights the importance of performing selective renal venous sampling for the preoperative diagnosis of JCT.

This work was supported by a Grant-in-Aid for Young Scientists (B) from the Japan Society for the Promotion of Science (JP16K20133). The authors declare no competing interests.