Satoh K
Department of Urology, Akita University School of Medicine.
Nihon Hinyokika Gakkai Zasshi. 1993 Mar;84(3):497-506. doi: 10.5980/jpnjurol1989.84.497.
The present study was performed to investigate the pontine control of the internal urethral sphincter (IUS) activity using 13 supracolicular decerebrate female dogs. The lower urinary tract function was evaluated by measuring the bladder and the IUS pressure and the external urethral sphincter (EUS) EMG. Bilateral ureters were cannulated and urine was drained extracorporeally. The bladder neck was ligated to induce a isovolumetric bladder contraction, and the urethra was separated from the bladder to evaluate the function of the bladder and the urethra separately. Electrical stimulation (ES) (0.3 m sec. pulse, 50 Hz, 10-100 microA, 3 sec.) in the pontine micturition center (PMC) was carried out using a microelectrode (10-30 microns in tip diameter). The sympathetic chains, hypogastric nerves and pelvic nerves were identified for preparing the nerve transection. 1) ES in the PMC evoked a bladder contraction and a relaxation of the IUS and EUS. This response was similar to the micturition reflex induced by slow filling of the bladder with saline. 2) The threshold intensity for evoking the IUS pressure drop (i.e. IUS relaxation) was equal to or lower than that for the bladder contraction. The latencies from the ES in the PMC to the IUS relaxation and to the bladder contraction were 0.24 +/- 0.14 sec. (mean +/- S.D.) and 0.42 +/- 0.08 sec., respectively. 3) ES in the PMC evoked the IUS relaxation even when the bladder was empty. 4) Transection of the sympathetic chains had no influence on the IUS relaxation by ES in the PMC. Transection of the hypogastric nerves not only decreased the urethral resting pressure but also reduced the urethral pressure drop by ES. Transection of the pelvic nerves abolished the IUS relaxation as well as the bladder contraction by ES. 5) Phentolamine decreased the urethral pressure between ESs and reduced the degree of the urethral pressure drop to the ES. Phenylephrine increased not only the urethral pressure between ESs but also the degree of the pressure drop by the ES. Propranolol and atropine die not affect the urethral pressure changes to the ESs. Hexamethonium abolished the urethral responses. These results indicate that the PMC regulates the IUS activity as well as the bladder activity. These results also suggest that the excitation of the PMC produces the IUS relaxation through the pelvic nerve pathway as well as the hypogastric nerve pathway. The IUS relaxation through the pelvic nerve pathway is mediated by non-adrenergic and non-cholinergic mechanisms.
本研究旨在使用13只去大脑皮层以上的雌性犬来研究脑桥对尿道内括约肌（IUS）活动的控制。通过测量膀胱和IUS压力以及尿道外括约肌（EUS）肌电图来评估下尿路功能。双侧输尿管插管，尿液体外引流。结扎膀胱颈以诱导膀胱等容收缩，并将尿道与膀胱分离以分别评估膀胱和尿道的功能。使用微电极（尖端直径为10 - 30微米）在脑桥排尿中枢（PMC）进行电刺激（ES）（0.3毫秒脉冲，50赫兹，10 - 100微安，3秒）。识别交感神经链、腹下神经和盆神经以准备进行神经横断。1）PMC中的ES引起膀胱收缩以及IUS和EUS松弛。这种反应类似于用盐水缓慢充盈膀胱诱导的排尿反射。2）引起IUS压力下降（即IUS松弛）的阈值强度等于或低于膀胱收缩的阈值强度。从PMC中的ES到IUS松弛和膀胱收缩的潜伏期分别为0.24±0.14秒（平均值±标准差）和0.42±0.08秒。3）即使膀胱为空，PMC中的ES也会引起IUS松弛。4）交感神经链横断对PMC中ES引起的IUS松弛没有影响。腹下神经横断不仅降低了尿道静息压力，还减少了ES引起的尿道压力下降。盆神经横断消除了ES引起的IUS松弛以及膀胱收缩。5）酚妥拉明降低了ES之间的尿道压力，并降低了对ES的尿道压力下降程度。去氧肾上腺素不仅增加了ES之间的尿道压力，还增加了ES引起的压力下降程度。普萘洛尔和阿托品不影响对ES的尿道压力变化。六甲铵消除了尿道反应。这些结果表明，PMC调节IUS活动以及膀胱活动。这些结果还表明，PMC的兴奋通过盆神经途径以及腹下神经途径产生IUS松弛。通过盆神经途径的IUS松弛由非肾上腺素能和非胆碱能机制介导。
