Shafik A, El-Sibai O
Department of Surgery and Experimental Research, Cairo University, Egypt.
Arch Androl. 2000 Jan-Feb;44(1):77-83. doi: 10.1080/014850100262443.
The ejaculatory mechanism involves 2 reflexes: the "glans-vasal," which seems to bring the semen to the posterior urethra (emission phase of ejaculation), and the "urethromuscular" which ejects it to the exterior (ejection phase). This study investigated the mechanism of bulbocavernosus muscle (BCM) contraction, once the seminal fluid reaches the bulbous urethra. The study included 14 healthy male volunteers (mean age 37 +/- 10.2 SD years). To test the response of the BCM to urethral distension, a 10F balloon-tipped catheter was introduced into the prostatic urethra and filled with saline in increments of 0.25 mL: a needle electrode recorded the response. The balloon was then withdrawn to lie in the membranous. bulbous, and pendulous urethra and the test was repeated at each site. The latency of the muscle response was calculated. The BCM response to each of the anesthetized bulbous urethra and anesthetized BCM was recorded. Distension of the prostatic, membraneous, or pendulous urethra effected no BCM EMG response. Bulbous urethral distension with 0.25 mL of saline also produced no muscle response, whereas distension with 0.5 mL and up to 1.5 mL caused increased EMG activity of the BCM. The muscle response augmented with the increase of the distending volume. The mean latency was 10 +/- 1.3 ms and showed no significant change (p > .05) with the different distending volumes. Neither the anesthetized bulbous urethra nor the anesthetized BCM responded to bulbous urethral distension. The BCM contraction upon distension of the bulbous urethra is probably reflex and mediated through the urethrocavernosus reflex. Small-volume distension did not effect BCM contraction. The latter presumably propels the semen from the posterior to the pendulous urethra. It is suggested that the urethrocavernosus reflex be included in current andrologic investigations for patients with ejaculatory disorders.
“龟头 - 输精管”反射，它似乎将精液输送至后尿道（射精的排精期），以及“尿道 - 肌肉”反射，它将精液排出体外（射精期）。本研究调查了精液到达球部尿道后球海绵体肌（BCM）收缩的机制。该研究纳入了14名健康男性志愿者（平均年龄37±10.2标准差岁）。为测试BCM对尿道扩张的反应，将一根10F带气囊导管插入前列腺尿道并以0.25 mL增量注入生理盐水：用针电极记录反应。然后将气囊撤回至膜部、球部和悬垂部尿道，并在每个部位重复该测试。计算肌肉反应的潜伏期。记录BCM对麻醉的球部尿道和麻醉的BCM的每种反应。前列腺、膜部或悬垂部尿道的扩张未引起BCM肌电图反应。用0.25 mL生理盐水扩张球部尿道也未产生肌肉反应，而用0.5 mL至1.5 mL扩张则导致BCM的肌电图活动增加。肌肉反应随扩张体积的增加而增强。平均潜伏期为10±1.3毫秒，且在不同扩张体积下无显著变化（p>.05）。麻醉的球部尿道和麻醉的BCM对球部尿道扩张均无反应。球部尿道扩张时BCM的收缩可能是反射性的，并通过尿道海绵体反射介导。小体积扩张未引起BCM收缩。后者可能将精液从后尿道推进至悬垂部尿道。建议将尿道海绵体反射纳入当前对射精障碍患者的男科检查中。
