Damaser M S, Lehman S L
Bioengineering Graduate Group, UC Berkeley 94720, USA.
J Biomech. 1996 Dec;29(12):1615-9.
Overdistension of the urinary bladder, secondary to outlet obstruction, causes cellular changes in the bladder wall, including hypertrophy of the smooth muscle cells, which increase bladder mass. To investigate the effects of increased mass on the cystometrogram (CMG), we have developed two mathematical models. In the first model, we assume that mass is added such that the largest bladder volume at zero transmural pressure, the zero pressure volume (ZPV), is constant, It predicts increased pressures and decreased compliance in the CMG. In the second model, we assume that both mass and ZPV increase proportionally. It predicts unchanged pressures, increased compliance, and increased capacity in the CMG. These results allow use to divide animal experiments in the literature into two groups. Cystometrograms performed on animals that have had outlet obstruction induced by a cuff method, inducing a small increase in mass, belong to the first group: hypertrophy with no change in ZPV. Cystometrograms performed on animals that have had outlet obstruction induced by a ligature method, inducing a large increase in mass, belong to the second group: hypertrophy with increased ZPV. We conclude that increased ZPV results from a more severe obstruction which is indicated by the increased capacity and compliance.
继发于出口梗阻的膀胱过度扩张会导致膀胱壁细胞发生变化，包括平滑肌细胞肥大，进而增加膀胱质量。为了研究质量增加对膀胱压力容积测定（CMG）的影响，我们建立了两个数学模型。在第一个模型中，我们假设增加质量时，零跨壁压下的最大膀胱容积（零压力容积，ZPV）保持不变，该模型预测CMG中的压力升高和顺应性降低。在第二个模型中，我们假设质量和ZPV成比例增加。该模型预测CMG中的压力不变、顺应性增加和容量增加。这些结果使我们能够将文献中的动物实验分为两组。通过袖带法诱导出口梗阻、导致质量小幅增加的动物所进行的膀胱压力容积测定属于第一组：肥大但ZPV无变化。通过结扎法诱导出口梗阻、导致质量大幅增加的动物所进行的膀胱压力容积测定属于第二组：肥大且ZPV增加。我们得出结论，ZPV增加源于更严重的梗阻，这表现为容量和顺应性增加。
