Re: Preventive Effect of Hydrogen Water on the Development of Detrusor Overactivity in a Rat Model of Bladder Outlet Obstruction

To the Editor: We read with interest the article by Miyazaki et al, who report that hydrogen water can ameliorate bladder dysfunction secondary to bladder outlet obstruction (BOO) by attenuating oxidative stress. According to several recent reports, bladder ischemia and oxidative stress clearly contribute to the pathogenesis of bladder wall remodeling. However, the previous view is that this activity is caused by mechanical stimuli. Our group also found that mechanical stimuli contribute to phenotypic changes of bladder smooth muscle cells, which are thought to represent the beginning of bladder wall remodeling. Is bladder ischemia really caused by BOO? A BOO animal model has been used for many years, although little is known about damage to the blood supply caused by surgery. To our knowledge, rat and mouse bladders are oval shaped, and bladder vessels depart from the bladder neck. The posterior urethra, which can be ligated, is short and difficult to identify unless operating under a microscope but there is no reported microsurgery of BOO. If the bladder neck were pulled over or ligated, bladder ischemia would occur. Researchers have reported activation of the hypoxia inducible factors pathway even 1 day postoperatively in a mouse model of BOO. Is this activation possibly caused by the operation? We would like to ask Miyazaki et al whether we need to slightly ligate the posterior urethra in the control group because it will create equal damage to bladder vessels on the bladder neck between the BOO and control groups. In addition, Wang et al reported a novel animal model of bladder outlet obstruction, in which hyaluronic acid periurethral injection generated a simple, effective and persistent animal model of BOO.