Boggs Joseph W, Wenzel Brian J, Gustafson Kenneth J, Grill Warren M
Department of Biomedical Engineering, Duke University, Box 90281, Durham, NC 27708-0281, USA.
J Neurophysiol. 2005 May;93(5):2688-97. doi: 10.1152/jn.00978.2004. Epub 2004 Dec 15.
Reflexes mediated by urethral sensory pathways are integral to urinary function. This study investigated the changes in bladder pressure and urethral sphincter activity resulting from electrical stimulation of afferents in the deep perineal nerve (DP), which innervates the urethra and surrounding muscles, before and after acute spinal cord transection (SCT) in cats anesthetized with alpha-chloralose monitored by blood pressure and heart rate. DP stimulation elicited bladder contractions before and after SCT but only if the bladder contained a sufficient volume of fluid (78% of the volume needed to cause distention-evoked reflex contractions). The volume dependency was mediated by a neuronal mechanism in the lumbosacral spinal cord and was not attributable to length-tension properties of the detrusor muscle. Stimulation at 2-40 Hz initiated bladder contractions, but 20-40 Hz was more effective than lower frequencies in evoking and sustaining bladder contractions for the duration of the stimulus train. Decreases in urethral sphincter activity occurred during sustained bladder contractions evoked by 20- to 40-Hz stimulation before and within 16 h after SCT. After SCT, average bladder pressure increases evoked by DP stimulation were smaller than those evoked before SCT, but in some animals, bladder pressures elicited by DP stimulation continued to increase as time after SCT increased and reached pretransection amplitudes at 8-16 h posttransection. These data confirm the presence of a spinal circuit that can mediate coordinated bladder-sphincter responses and show that afferents from the DP can activate this circuit under appropriate conditions.
由尿道感觉通路介导的反射是泌尿功能不可或缺的一部分。本研究在以α-氯醛糖麻醉的猫中，通过监测血压和心率，研究了在急性脊髓横断（SCT）前后，电刺激支配尿道及周围肌肉的会阴深神经（DP）传入神经所引起的膀胱压力和尿道括约肌活动的变化。在SCT前后，DP刺激均可引发膀胱收缩，但前提是膀胱中含有足够量的液体（引起扩张诱发反射性收缩所需体积的78%）。这种体积依赖性是由腰骶脊髓中的神经元机制介导的，并非归因于逼尿肌的长度-张力特性。2-40Hz的刺激可引发膀胱收缩，但在刺激序列持续期间，20-40Hz在引发和维持膀胱收缩方面比低频更有效。在SCT前以及SCT后16小时内，由20-40Hz刺激诱发的持续性膀胱收缩过程中，尿道括约肌活动会降低。SCT后，DP刺激引起的平均膀胱压力升高幅度小于SCT前，但在一些动物中，DP刺激引起的膀胱压力随着SCT后时间的增加而持续升高，并在横断后8-16小时达到横断前的幅度。这些数据证实了存在一个可介导膀胱-括约肌协调反应的脊髓回路，并表明在适当条件下，来自DP的传入神经可以激活该回路。
