Striated muscle fiber compositions of human male urethral rhabdosphincter and levator ani
Striated muscle fiber compositions of human male urethral rhabdosphincter and levator ani
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DOI：
10.1016/s0022-5347(05)00697-x
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发表时间：
2006-04-01
影响因子：
6.6
通讯作者：
Mimata, H
中科院分区：
文献类型：
--
作者：
Sumino, Y;Sato, F;Mimata, H
目的：为了更好地了解横纹括约肌和提肛肌是如何维持排尿的，我们阐明了男性尿道周围横纹肌纤维的收缩特性。材料和方法：取自52例接受根治性前列腺切除术或根治性膀胱切除术的男性患者的肌肉标本。这些标本被冷冻在液氮中。用肌原纤维ATPase在不同pH值(pH 4.2、4.6和10.6)下对10亩厚冰冻切片进行染色，并对定量参数和纤维类型分布进行评估。结果：52例患者中，37例肌球蛋白重链可分为2种主要纤维型：1型(慢抽动)和2型(快抽动)。虽然在RS和LA肌群中以1型肌纤维为主(RS69.6+/-2.7%，LA 67.0+/-2.0%)，但RS组的平均肌纤维直径(平均面积906+/-86mum(2))明显小于LA组(平均面积2967170mum(2))(p<；0.0001)。在11例标本中，2型肌纤维可分为快抗疲劳型(2A型)和快疲劳型(2B)。2A型纤维明显高于2B型纤维(p<；0.05)。同样，MHC分析发现这11例标本中2A型纤维表达产物(MHC 2A)的比例显著高于2B型纤维表达产物(MHC 2X)(p<；0.05)。结论：RS和LA通过缓慢收缩参与了尿控机制。此外，与洛杉矶的肌肉纤维相比，RS中肌肉纤维的平均尺寸较小，表明其抗疲劳能力更强，因为较小的纤维对代谢底物的扩散距离较短。这些结果应该有助于更详细地了解男性尿道周围横纹肌的功能。
Purpose: We clarified the contractile properties of human male periurethral striated muscle fibers to better understand how the rhabdosphincter and the levator ani maintain urinary continence.Materials and Methods: Muscle specimens were obtained from 52 male patients who underwent radical prostatectomy or radical cystectomy. The specimens were frozen in liquid nitrogen. Frozen sections (10 mu m thick) were stained with myofibrillar ATPase at different pH values (pH 4.2, 4.6 and 10.6), and evaluated for quantitative parameters and fiber type distribution. Myosin heavy chain analysis was performed using SDS-PAGE.Results: Of all 52 cases 37 provided specimens that could be divided into the 2 major fiber types, type 1 (slow twitch) and type 2 (fast twitch). Although type 1 muscle fibers were predominant in RS and LA muscle groups (RS 69.6 +/- 2.7%, LA 67.0 +/- 2.0%), mean muscle fiber size was significantly smaller in RS (mean area 906 +/- 86 mu m(2)) than in LA (mean area 2,967 170 mu m(2)) (p < 0.0001). In 11 specimens type 2 muscle fibers could be subdivided into types 2A (fast fatigue resistant) and 2B (fast fatigable). Type 2A fibers were significantly more prevalent than type 2B fibers (p < 0.05). Likewise, MHC analysis of these 11 specimens found a significantly higher percentage of fiber type 2A expression products (MHC 2A) than of fiber type 2B expression products (MHC 2X) (p < 0.05).Conclusions: RS and LA contribute to urinary continence mechanism by slow contraction. Moreover, the smaller mean size of muscle fibers in RS suggests more fatigue resistance compared with muscle fibers in LA because small fibers have a shorter diffusion distance for metabolic substrates. These results should help contribute to a more detailed understanding of the function of periurethral striated muscles in the human male.