Motility of the Urinary Bladder in Cats during Filling at Physiological Rates: I. Intravesical Pressure Patterns Studied by a New Methods of Cystometry

Natural filling of the bladder has been studied by a new cystometric method termed “Controlled Slow Cystometry” (CSC). A suprapubic double‐catheter was used for filling from a constant‐volume infusion pump and for continuous intravesical pressure recording. A rate‐unit and 5 rate‐models were proposed for the filling procedure. The rate‐unit was defined as the normal hour‐diuresis (HD) using 26 ml/kg per day as a normal value. The rate‐models were considered as physiological and relevant to illustrate the normal variations in excretion of urine. Maximal physiological increase in urinary excretion was measured to be 15 times the normal. Intravesical pressure recording was performed during filling from the pump according to the rate‐models as well as during normal and increased urinary excretion (5 % glucose i.v.). A differentiated pressure reaction related to the rate of filling was found. Below the rate of 2.4 HD the pressure curve was flat. Pressure increase started at individual rates between 2.4–7 HD. When the rate fell below this value the pressure stabilized at a higher level (pressure accumulation phenomenon). Accordingly, micturition was elicited in the same animal at clearly separated pressure levels depending on the foregoing rates of filling. The pressure patterns demonstrated are considered as basic motility reactions present during natural filling.