Groen J, Van Asselt E, Van Mastrigt R, Kranse M, Bosch R
Department of Urology, Erasmus University Rotterdam, The Netherlands.
J Urol. 1996 Apr;155(4):1471-6.
The resistance offered to urinary flow by the urethra is one of the factors determining the course of micturition. It was the aim of the present work to study the dependence of urethral resistance on the degree of relaxation of the urethra.
Experiments were done in the guinea pig. Ten animals were used. In 5 animals saline was forced through the (unrelaxed) urethra at imposed flow rates in the range of 1.1 to 43.0 ml. per minute while the urethral pressure was measured. Second degree polynomials were fitted to the pressure/flow data. In the other 5 animals micturition contractions were evoked and pressure/flow plots were derived from the measured signals. A straight line was fitted to the lowest pressure values at each flow rate in these plots. These pressure values represent the most relaxed state of the urethra in these voidings.
The pressures measured in the unrelaxed urethra were much higher than the pressures measured during voiding in the same flow rate range, but the intercepts of the mathematical equations fitted to the pressure/flow data on the pressure axis were not significantly different in the 2 groups.
The unrelaxed urethra has a much "steeper" pressure/flow characteristic than the relaxed urethra. However, the urethral closing pressure, that is, the intercept of the pressure/flow characteristic on the pressure axis, does not depend on the state of relaxation of the urethra.
尿道对尿流的阻力是决定排尿过程的因素之一。本研究旨在探讨尿道阻力与尿道松弛程度之间的关系。
实验在豚鼠身上进行。共使用10只动物。对其中5只动物，在1.1至43.0毫升/分钟的设定流速下，将生理盐水强行通过（未松弛的）尿道，同时测量尿道压力。将二次多项式拟合到压力/流量数据上。对另外5只动物诱发排尿收缩，并从测量信号中得出压力/流量图。在这些图中，对每个流速下的最低压力值拟合一条直线。这些压力值代表了这些排尿过程中尿道最松弛的状态。
在相同流速范围内，未松弛尿道测得的压力远高于排尿时测得的压力，但两组中拟合压力/流量数据的数学方程在压力轴上的截距无显著差异。
未松弛的尿道比松弛的尿道具有更“陡峭”的压力/流量特性。然而，尿道闭合压力，即压力/流量特性在压力轴上的截距，并不取决于尿道的松弛状态。
