Haugaard N, Potter L, Wein A J, Levin R M
Department of Surgery, University of Pennsylvania School of Medicine, Philadelphia.
J Urol. 1992 May;147(5):1391-3. doi: 10.1016/s0022-5347(17)37580-8.
Previous studies have demonstrated that partial outlet obstruction in rabbits induced a significant decrease in oxidative metabolism in urinary bladder smooth muscle. The current experiments were designed to determine whether the decreased oxidative metabolism of obstructed bladder tissue is associated with alterations in the activities of specific mitochondrial enzymes. The activities of two important enzymes in the tricarboxylic acid cycle, malate dehydrogenase and citrate synthase, were measured in samples of bladder body and base from normal bladders and in bladders from rabbits in which partial outlet obstruction had been produced seven days prior to the experiments. The results can be summarized as follows: malate dehydrogenase activity was similar in bladder body and base isolated from control rabbits; and decreased by approximately 40% in both segments of the bladder isolated from obstructed rabbits. In contrast to malate dehydrogenase, citrate synthase activity was significantly higher in the bladder body than in the base of normal rabbits. Outlet obstruction caused about a 50% decrease in activity of this enzyme in the bladder body, but had no significant effect on citrate synthase activity of the bladder base. These findings demonstrate that the deficiency in bladder function following partial outlet obstruction is associated with a marked decrease in the activities of two essential enzymes in oxidative metabolism: malate dehydrogenase and citrate synthase. This decrease in enzyme activity is consistent with the previously observed decrease in oxidative metabolism and would be expected to lead to an inability of the tissue to supply sufficient metabolic energy for proper contractile function.
先前的研究表明，兔的部分出口梗阻会导致膀胱平滑肌的氧化代谢显著降低。当前的实验旨在确定梗阻性膀胱组织氧化代谢的降低是否与特定线粒体酶活性的改变有关。在正常膀胱的膀胱体和底部样本以及在实验前七天产生部分出口梗阻的兔膀胱中，测量了三羧酸循环中两种重要酶——苹果酸脱氢酶和柠檬酸合酶的活性。结果可总结如下：从对照兔分离的膀胱体和底部中，苹果酸脱氢酶活性相似；而从梗阻兔分离的膀胱的两个节段中，该酶活性均降低了约40%。与苹果酸脱氢酶不同，正常兔膀胱体中的柠檬酸合酶活性显著高于底部。出口梗阻使膀胱体中该酶的活性降低了约50%，但对膀胱底部的柠檬酸合酶活性没有显著影响。这些发现表明，部分出口梗阻后膀胱功能的缺陷与氧化代谢中两种关键酶——苹果酸脱氢酶和柠檬酸合酶的活性显著降低有关。酶活性的这种降低与先前观察到的氧化代谢降低一致，并且预计会导致组织无法为正常收缩功能提供足够的代谢能量。
