Stepwise cystometry : a new method to investigate properties of the urinary bladder

The urinary bladder has a twofold function : 1. to store urine and 2. to expel it if necessary under complete voluntary control. The bladder can store various volumes of urine at a low and approximately constant intravesical pressure until capacity is reached. In the literature, this characteristic of the bladder was originally ascribed to reflex mechanisms (Mosso and Pellacani, 1882; Ausems, 1957). However, experimental evidence to show that inherent properties of the detrusor muscle, independent of neurogenic control, play an important role, has been put forward by some authors (Nesbit and Lapides, 1948; Tang and Ruch, 1955). Remington and Alexander (1955) have distinguished active and passive properties of the detrusor muscle. They demonstrated that viscoelastic properties of smooth muscular organs are determined primarily by passive components of the tissue. The objectives of the studies presented here can be summarized as follows: 1. To demonstrate again that the urinary bladder has viscoelastic properties. 2. To describe quantitatively the physical properties of the bladder wall in the collection phase by means of a passive model. 3. To study the influence of the active elements on passive behaviour. 4. To compare the present method with the classical cystometry with regard to its value in representing physical characteristics of the urinary bladder. 5. To propose a new cystometry method by which the physical properties of bladders can be quantitatively analysed. These properties are represented in parameters, based on passive features

New concepts in relation to urge and detrusor activity

Investigations of micromotion characteristics of bladder wall strips and pressure wave phenomena in total bladders in vitro and in vivo indicate that micromotion phenomena occur in the bladder wall. Local contractions can occur without an increase in tension or pressure, because other parts are in antiphase. Local contractions stretch surrounding tissues, which can stimulate fast stretch receptors. Synchronisation of these micromotion phenomena appears to be possible. Hence, above threshold levels urge can theoretically occur, even in the absence of a pressure increase. This hypothesis could explain the weak relation between urge and pressure. The distinction between motor and sensory urge could be artifactual based on a misunderstanding of fundamental bladder wall processes

Effect of partial urethral obstruction on force development of the guinea pig bladder

We created gradual partial urethral obstruction in 20 guinea pigs using silver jeweler's jump rings. After 4 or 8 weeks obstruction all animals underwent cystometry and were assigned to one of five urodynamic categories: normal, high pressure voiding, unstable, low compliance, or decompensated. After sacrifice, the contractile responses of bladder strips to electrical field stimulation of intramural nerves, direct electrical muscle stimulation, 0.1 mM carbachol, and high K + solution were sampled by computer for phase plot analysis. Following 8 weeks obstruction, the value of the phase plot parameter Fiso, indicative of the number of contractile muscle units, was reduced to 60% of the control response to nerve stimulation (P < 0.05) and to 77% of the control response to carbachol stimulation (P < 0.05). Parameter C, the slope of the phase plot (indicative of unit recruitment during force development), was unchanged for all forms of stimulation. Although in the latter case not statistically significant, obstruction affected responses to nerve and muscle stimulation similarly suggesting that muscle change may possibly be a common denominator of dysfunction. In view of the reduction in Fiso and the increase in bladder weight, instability may represent a more advanced form of dysfunction due to obstruction than high pressure voiding