Login to Access Video or Poster Abstract: MP17-19
Sources of Funding: Xinhua Zhang is supported by National Natural Science Foundation of China (N.81270843 and N.81160086)

Introduction

Benign prostatic hyperplasia (BPH) is a common disease in aging male, which mainly caused by increased prostatic smooth muscle (SM) tone and volume. Lowering SM tone with α-blockers are one of the most effective treatment for BPH. SM and non-muscle (NM) myosin play important roles mediating SM tone and cell proliferation. But it was less studied in the prostate.

Methods

Rat prostate and cultured primary human prostate SM and epithelial cells were used. In vitro organ bath studies were performed to explore contractility of rat prostate, corpus cavernosum, bladder and aorta. SMM isoforms were determined with competitive RT-PCR. SM myosin heavy chain (MHC) and NM MHC isoforms (NMHC-A, NMHC-B and NMHC-C) were further analyzed with Western Blot and immunofluorescence.

Results

SM MHC was abundantly displayed in rat prostate, predominantly in the outer stroma layer. Prostatic SM generated significant force in response to KCl depolarization and phenylephrine (PE)-mediated stimulation in a dose-dependent manner with an intermediate tonicity between bladder typical phasic and aorta tonic contractility. And time to 50% PE mediated maximum contraction of prostate (13.2±2.6 S) was between that of bladder (5.7±1.2 S) and aorta (24.2±2.4 S). Correlated with this kind of intermediate tonicity, rat prostate mainly expressed LC_17a and SM1 but with relatively equal expression of SM-B at the mRNA level. Meanwhile, isoforms of NMHC-A, B, C were also abundantly detected in the prostate with SMM present only in SM cells, NMHC-A and NMHC-B both present in SM and endothelial cells, and NMHC-C expressed only in the SM cells. Furthermore, NM expression in rat prostate was more than 2-fold higher than that of rat bladder, while SMM expression was found to be similar. Additionally, SMM specific inhibitor Blebbistatin could potently relax PE pre-contracted prostate SM, comparable to the effect of sodium nitroprusside (nitric oxide donor) and H-1152 (a specific, strong and membrane-permeable inhibitor of Rho-kinase)

Conclusions

Our novel data demonstrated the expression and functional activities of SMM and NM isoforms in the rat prostate. It is suggested that the isoforms of SMM and NM could play important roles in BPH development.

Funding

Xinhua Zhang is supported by National Natural Science Foundation of China (N.81270843 and N.81160086)