The investigation of ureteral sympathetic innervation, using semi-serial sections: why does the alpha1-adrenergic receptor antagonist work well for ureteral stones?

PURPOSE: The efficacy of the alpha1-adrenergic receptor antagonist against ureteral stones was clarified on the basis of ureteral sympathetic innervation.
METHODS: Semi-serial sections of retroperitoneal tissue were prepared from one each of donated male and female cadavers, and the nerve distribution in the ureter was investigated. Sympathetic nerve fibers were identified by immunostaining of tyrosine hydroxylase.
RESULTS: We were able to prepare semi-serial sections of the male right and female left ureters, in which 202 and 210 sympathetic nerve bundles were distributed. Sympathetic nerve bundles were distributed throughout the entire ureter. The number of nerve bundles was highest in the portion close to the bladder in the male right ureter (eight bundles/mm) and in the portion crossing the common iliac artery in the female left ureter (seven bundles/mm).
CONCLUSION: Adrenergic sympathetic nerve fibers were distributed throughout the ureter. Therefore, alpha1-adrenergic receptor antagonists may act on the entire ureter, reducing its tonus. As a result, these antagonists may be useful for improving the stone-freeing rate and inhibiting pain attacks.