Rapid injection cystometry and hydroxyproline content in the acutely overdistended rabbit bladder

Bladder overdistention occurs in a variety of clinical circumstances including trauma, benign prostate hyperplasia, urethral stricture, and in the post‐operative and postpartum state. Overdistention can lead to injury and subsequent failure of the bladder contractile mechanism with loss of normal micturition. To date, there is no useful clinical test to predict which individuals will recover effective voiding function. Similarly, the ability of the bladder to tolerate a given degree of overdistention, and/or the time required to induce a permanent injury, are also unknown. Four degrees of bladder overdistention injury (1, 2, 3, and 4 hours) were induced in a randomized rabbit model. The following day, the animals underwent rapid injection cystometry and at 10 days following injury the bladders were assayed for hydroxyproline content. The results show that the hydroxyproline level (nmol/mg) was directly related to the overdistention interval (r = 0.30803) and inversely related to the maximum height of the contraction curve (r = −0.31573). Further, the rapid cystometry curves found were of two different types and correlated highly with hydroxyproline levels (P<.001). These contraction curve types are distinct at the maximum pressure point suggesting persistent active contractile forces. These findings suggest that the shape of the curve at the maximum pressure point may be clinically more useful than the half decay time or shape of the relaxation curve as suggested by prior work in this area.