Kuo H C
Department of Urology, Buddhist Tzu Chi General Hospital, Hualien, Taiwan, ROC.
J Formos Med Assoc. 1997 Sep;96(9):691-6.
Intravesical capsaicin at high concentration (1 mmol/L) inhibits the micturition reflex and detrusor contractility. To investigate the mechanism, we compared rats that had been desensitized by capsaicin at birth with control rats. In vivo cystometrography was performed with normal saline (n = 5) or 1 mmol/L capsaicin (n = 5), then an isolated whole bladder contractility study with electrical field stimulation, bethanechol, and KCl was carried out. In the bladders with normal saline cystometrography and after isolated bladder study, 0.5 mL of 1 mmol/L capsaicin was instilled into the bladders and another set of stimulations by electrodes, bethanechol, and KCl was given. The bladders of capsaicin-desensitized rats showed the presence of detrusor reflexes but diminished amplitudes of detrusor contractions. There was no urinary retention or increased intravesical pressure in these desensitized bladders after capsaicin cystometrography. The detrusor contractility in the isolated whole bladder study showed no significant difference between the control and experimental bladders. After 1 mmol/L capsaicin cystometrography the bladders had little contractility compared with bladders after saline cystometrography. The bladders of the desensitized rats increased in weight compared to the controls. Intravesical administration of 1 mmol/L capsaicin induced an initial excitatory effect on the micturition reflex and final urinary retention in control rats. After capsaicin treatment at birth, these effects no longer existed but the depressant effect of capsaicin on detrusor contractility persisted. We conclude that a high concentration of intravesical capsaicin acutely inhibits the micturition reflex and detrusor contractility. Neonatal desensitization by capsaicin can depress the detrusor contractility in rats but the micturition reflex is not affected.
高浓度（1毫摩尔/升）的膀胱内辣椒素可抑制排尿反射和逼尿肌收缩力。为研究其机制，我们将出生时经辣椒素脱敏的大鼠与对照大鼠进行了比较。用生理盐水（n = 5）或1毫摩尔/升辣椒素（n = 5）进行体内膀胱测压，然后进行电场刺激、氨甲酰甲胆碱和氯化钾刺激下的离体全膀胱收缩性研究。在生理盐水膀胱测压及离体膀胱研究后的膀胱中，向膀胱内注入0.5毫升1毫摩尔/升辣椒素，并再次给予电极、氨甲酰甲胆碱和氯化钾刺激。辣椒素脱敏大鼠的膀胱存在逼尿肌反射，但逼尿肌收缩幅度减小。辣椒素膀胱测压后，这些脱敏膀胱未出现尿潴留或膀胱内压升高。离体全膀胱研究中，对照膀胱与实验膀胱的逼尿肌收缩性无显著差异。与生理盐水膀胱测压后的膀胱相比，1毫摩尔/升辣椒素膀胱测压后膀胱收缩力减弱。与对照组相比，脱敏大鼠的膀胱重量增加。膀胱内给予1毫摩尔/升辣椒素对对照大鼠的排尿反射有初始兴奋作用，最终导致尿潴留。出生时经辣椒素处理后，这些作用不再存在，但辣椒素对逼尿肌收缩力的抑制作用依然存在。我们得出结论，高浓度的膀胱内辣椒素可急性抑制排尿反射和逼尿肌收缩力。辣椒素对新生大鼠进行脱敏可降低其逼尿肌收缩力，但不影响排尿反射。
