老龄大鼠膀胱生理特性改变的实验研究

Physiological Changes in Urinary Bladder of Aging Rats:An Experimental Study

目的:探讨老龄大鼠膀胱生理特性的改变及其可能机制。方法:雌性W istar大鼠分为年轻成年组(6月龄)和老龄组(24月龄),通过在体充盈期膀胱测压,判定逼尿肌不稳定的发生率,比较两组最大膀胱容量和漏尿点压的差异;在水浴条件下,分别测量两组新鲜逼尿肌条的自发收缩频率、应力作用下的反应张力、对电刺激的反应强度等指标,并对实验结果进行统计学分析。结果:与年轻成年组相比,老龄大鼠表现为更易出现逼尿肌不稳定;麻醉条件下最大膀胱容量显著增加(P<0.01),漏尿点压无明显差异;自发收缩频率显著增高(P<0.05)。老龄大鼠逼尿肌条在应力增加时,张力上升缓慢;应力降低时,张力下降迅速。应力改变时电刺激诱发收缩表现为与单纯应力改变时的张力改变相似,张力增加值在两组间无差异。结论:老龄膀胱功能的改变与自身逼尿肌兴奋性增加、高顺应性、弹性降低有关,肌源性改变是其主要因素。

Objective.To investigate the mechanism of urinary physiological changes in urinary bladder of aging rats. Methods：Female Wistar rats were divided into the young adult group （6-month old）and the aging group （24-month old）. In vivo,filling cystometry was performed in each rat of the two groups to evaluate the incidence of detrusor instability,and to compare the differeces in maximum bladder capability and pressure at the point of urine leakage. In vitro,detrusor strips of each rat in the two groups was suspended in a thermostatically controlled organ bath. And their spontaneous contraction frequency, reaction tension to stress and response intensity to electric stimuli were determined and statistically analyzed. Results：Compared with the young adult group,the aging group showed much more frequent detrusor instability ; the maximum bladder capacity was increased significantly in the aging rats under anesthetic condition and the frequency of spontaneous contraction was elevated significantly （P 〈 0. 05 ） ; there was no difference in leak point pressure between the two groups. In the aging rats, tension of detrusor strips rised slowly as the stress was increased,whereas it dropped quickly as the stress went down. Electric stimuli-induced contraction was similar to the changes in tension when only the stress altered and there was no difference in the increased value of tension between the two groups. Conclusions：Functional changes in detrusor in the aging bladder were related with increased excitability,increased compliance and decreased elasticity of ites own and myogenic modification was the primary factor.