RhoA/Rho kinase-mediated Ca2+ sensitization in the contraction of human prostate.
OBJECTIVE
The contractile mechanisms of prostatic smooth muscle have been extensively investigated at the receptor level. However, the intracellular mechanisms have not yet been fully elucidated, especially in human tissue. In the present study, we examined the functional role of RhoA/Rho kinase (ROCK), one of the major intracellular molecules involved in smooth muscle contraction, in the contraction of the human prostate.


METHODS
Ring preparations made of cultured human prostatic stromal cells (CHPSCs) or fresh human prostatic tissue was used for an isometric tension study. Gene transfer using baculovirus vector and alpha-toxin permeabilized preparations were also used.


RESULTS
RhoA, ROCK I and ROCK II proteins were all expressed in CHPSCs and fresh human prostatic tissue. In CHPSCs ring preparations, the contraction induced by endothelin (ET)-1 was enhanced by over-expression of RhoA and inhibited by ROCK inhibitor. In alpha-toxin permeabilized preparations, ET-1 or GTP-gammaS induced an additional contraction at a constant [Ca2+]i, that was inhibited by ROCK inhibitor. In fresh human prostatic tissue, norepinephrine (NE)-induced contraction was inhibited by ROCK inhibitor at a constant [Ca2+]i in alpha-toxin permeabilized preparations.


CONCLUSIONS
These results suggested that RhoA/ROCK-mediated Ca2+ sensitization is likely involved in the contraction of the human prostate. The antagonisms of this pathway may thus be useful as an alternative target in the treatment of benign prostatic hyperplasia (BPH).
Takahashi
Ryosuke
R
Department of Urology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
Nishimura
Junji
J
Division of Molecular Cardiology, Research Institute of Angiocardiology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
Seki
Narihito
N
Department of Urology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
Yunoki
Takakazu
T
Department of Urology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
Tomoda
Toshihisa
T
Department of Urology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
Kanaide
Hideo
H
Division of Molecular Cardiology, Research Institute of Angiocardiology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
Naito
Seiji
S
Department of Urology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine / Q000031:analogs & derivatives / Q000494:pharmacology; D000577:Amides / Q000494:pharmacology; D015153:Blotting, Western; D002118:Calcium / Q000502:physiology*; D002478:Cells, Cultured; D004791:Enzyme Inhibitors / Q000494:pharmacology; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000494:pharmacology; D006801:Humans; D066298:In Vitro Techniques; D008297:Male; D008875:Middle Aged; D009119:Muscle Contraction / Q000502:physiology; D011467:Prostate / Q000502:physiology*; D011725:Pyridines / Q000494:pharmacology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D010738:Type C Phospholipases / Q000494:pharmacology; D020742:rhoA GTP-Binding Protein / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology*
D000577:Amides; D004791:Enzyme Inhibitors; D011725:Pyridines; C108830:Y 27632; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D010738:Type C Phospholipases; D020742:rhoA GTP-Binding Protein; C049347:fasudil; D002118:Calcium