Correlation of in vitro pressure generation with urinary bladder function

Abstract

AbstractUrinary bladder function consists of a filling and storage phase followed by an active coordinated expulsion phase. A large part of our knowledge of bladder function, as well as bladder physiology and pharmacology, comes from a variety of in‐vivo and in‐vitro experimental animal models.Of the in‐vitro methodologies available for the study of bladder smooth muscle, the isolated bladder smooth muscle strip techniques and isolated whole bladder techniques are two of the most popular. In general, the ability to generate pressure in the non‐emptying whole bladder model is directly related to phasic contraction of the bladder smooth muscle, and can be equated with the response of isolated strips. Although both techniques generate useful and important information, one must be very careful in making conclusions concerning bladder function based solely on contractile data.We have studied the volume‐pressure relationship of the bladders of control rabbits and of those subjected to bladder outlet obstruction (2 week) and unilateral ischemia (2 week). For each bladder, in‐vitro cystometry, pressure generation, and the ability of the bladder to empty (in response to both bethanechol and field stimulation) was determined. Although it was clear that outlet obstruction and unilateral ischemia induced marked alterations in bladder compliance, capacity, and the ability to empty, bladder pressure generation was not significantly affected. These studies support the view that contractile studies in and of themselves cannot be used to describe the functional state of the bladder. Only through the application of several techniques including studies on bladder compliance, capacity, and the ability of the bladder to empty can the functional state of the bladder be evaluated.