Influences of androgen for detrusor function

本研究使用16周龄的雄性Sprague-Dawley大鼠。将大鼠分为去势组和对照组。去势后4周，采用离体膀胱逼尿肌条进行离体收缩实验，观察逼尿肌对激动剂的收缩反应、对电场刺激（EFS）的反应以及逼尿肌的力-速度关系。卡巴胆碱和α，β -亚甲基ATP的剂量反应曲线与两种逼尿肌条无差异。因此，去势后毒蕈碱受体和嘌呤受体的功能没有改变。EFS（15伏，0.5毫秒）产生频率依赖性收缩.在较低的频率（低于10 Hz），似乎有轻微的反应，去势组。然而，在高频率下，收缩反应没有改变。这些结果可能提示去势影响神经功能和/或嘌呤能神经元等神经递质的分泌。力量由肌肉收缩的力量（F）和速度（V）组成。因此，我们进行了等张收缩研究，以测量逼尿肌收缩的速度。当施加EFS（50 Hz）时，逼尿肌条在各种负荷下缩短。根据该缩短曲线的梯度计算该缩短速度。去势组的力-速度曲线位于对照组的曲线下方。每单位组织重量的平均功率，对照组为6.57 × 10^<-3>W/g，去势组为3.18 × 10^<-3>W/g。提示促尿素直接影响逼尿肌的收缩力。膀胱肌可能是雄激素作用的靶点。

Male Sprague-Dawley rats, 16 weeks old, were used for this study. These rats are divided into two groups both castration and control. 4 weeks after castration, using isolated detrusor strips which were taken from these both bladders and mounted in an organ bath, in vitro contraction studies were performed to evaluate the contractile responses to agonist, the responses to electrical field stimulation(EFS) and the force-velocity relation to determine power of detrusor muscle. The dose-response curves for carbachol and α, β -methylene ATP did not differ from both detrusor strips. Thus, function of muscarinc receptor and purinoceptor were not changed after castration. EFS (15 voltage, 0.5msec duration) produced frequency -dependent contraction. At lower frequency(below 10 Hz), there seems to be slightly weak responses in castration group. However, at high frequency, the contractile responses were not altered. These results may suggest that castration influences function of nerve and/or secretion of neurotransmitters such as purinergic neuron. Power consists of force(F) and speed contraction(V) of muscle. Thus, we carried out an isotonic contraction study to measure velocity of detrusor muscle contraction. When EFS (50Hz) is applied, detrusor strip shortens against various loads. This velocity of shortening is calculated from a gradient of this shortening curve. A force-velocity curve, of castration group is situated under the curve of control group. Average power per unit tissue weight were 6.57 × 10^<-3>watt/g on control group and 3.18 × 10^<-3>watt/g on castration group. This study suggests that ancirogen influences power of detrusor muscle, directly. Bladder muscle could be a possible target of androgen.