INVESTIGATIVE UROLOGY

Reperfusion injury of the rat bladder is worse than ischemia
Bratslavsky G, Kogan BA, Matsumoto S, Aslan AR, Levin RM
From the Division of Urology, Albany Medical College (GB, BAK, SM, ARA, RML), Department of Basic and Pharmaceutical Sciences, Albany College of Pharmacy (RML) and Stratton Veterans Affairs Medical Center (ARA), Albany, New York, and Department of Urology, Kinki University School of Medicine (SM), Osaka, Japan
J Urol. 2003; 170: 2086-90

• Purpose: Previous studies have demonstrated that in vivo and in vitro ischemia of the bladder results in decreased contractile responses. However, to our knowledge the effect of reperfusion following ischemia of the bladder is not known.
• Materials and Methods: Adult male rats were subjected to bilateral bladder ischemia and varying periods of reperfusion. In vivo ischemia was created for 4 hours by reversibly clamping the 2 vesical arteries for 4 hours. Reperfusion was produced by removing the clamps and allowing the animals to recover for 1 day, 1 week or 1 month after surgery. Following recovery bladders strips were studied using field stimulation (FS), carbachol and KCl. The maximal contractile response and rate of response generated were recorded digitally and analyzed.
• Results: The maximal responses to FS, carbachol and adenosine triphosphate (ATP) were not decreased by 4-hour ischemia alone, whereas the response to KCl was decreased significantly. The contractile responses to FS and KCl were significantly decreased after 1 day and 1 week of reperfusion. Responses after 1 month of reperfusion were increased significantly compared with responses after 1 week of reperfusion. The responses to ATP were not affected by ischemia or reperfusion. The contractile response to KCl was significantly more sensitive to ischemia than the responses to carbachol, ATP or FS, whereas the contractile response to FS was significantly more sensitive to reperfusion than the other forms of stimulation.
• Conclusions: This study demonstrates clearly that injury by reperfusion following ischemia is more detrimental than the effects of ischemia alone and FS contraction is the most sensitive form of stimulation to reperfusion damage. This study also demonstrates the ability of the bladder to recover from ischemic and reperfusion injuries.
  
  
• Editorial Comment
  This is a welcome research work on ischemia/ reperfusion injury in urogenital organs. There is increasing evidence suggesting that specific urinary tract dysfunctions are related directly to bladder smooth muscle hypoxia and ischemia. Despite recent understanding of the destructive effects of ischemia the importance of reperfusion injury to the bladder remains unclear. The authors clearly demonstrated that reperfusion injury was more detrimental to neurogenic stimulation than ischemia alone. Also, this study provides evidence that the bladder is able to recover from ischemic and reperfusion injuries.

Dr. Francisco J.B. Sampaio
Full-Professor and Chief, Urogenital Research Unit
State University of Rio de Janeiro
Rio de Janeiro, Brazil