The Profile Of Myosin Heavy Chain Isoforms In The Female Striated Urinary Sphincter Muscle

Objective: The main morphological structure of urinary continence in female is the urinary sphincter system, which contains urethral striated sphincter muscle, urethral smooth sphincter muscle, urethral submucosal connective tissue and urinary mucosa.The striated sphincter muscle that covered outside of the urethra plays the most important role in the urinary continence mechanism.The function of the urinary sphincter system is very complicated and precise. It can deal with various conditions which are from rest to stress. Detecting the relative content of myosin heavy chain isoforms of striated urethral sphincter in normal adult female can help us to better understand how the striated urethral sphincter works in maintaining urinary continence.Methods: Reverse transcriptase poly- merase chain reaction (RT-PCR) and SDS-Polyacrylamide gel electrophoresis (SDS-PAGE) were used to detect the expression of mRNA and protein of myosin heavy chain isoforms of striated urethral sphincter in normal adult female. The content of mRNA and protein were monitored and data were statistically analyzed. Results:The striated urethral sphincter of normal adult female express three myosin heavy chain isoforms:MHC-Ⅰ,MHC-Ⅱa and MHC-Ⅱx.The content of MHC-Ⅱx was most, MHC-Ⅰwas lest and MHC-Ⅱa was between them.Conclusions: Three myosin heavy chain isoforms were detected in the female urethral striated sphincter muscle: MHC-Ⅰ,MHC-Ⅱa and MHC-Ⅱx. The composition of a heterogeneous collection of muscle fiber types was the basis of the urinary continence under various conditions in human.