Actions of cAMP on calcium sensitization in human detrusor smooth muscle contraction

作者：Hayashi Maya; Kajioka Shunichi^*; Itsumi Momoe; Takahashi Ryosuke; Shahab Nouval; Ishigami Takao; Takeda Masahiro; Masuda Noriyuki; Yamaguchi Akito; Naito Seiji

来源：BJU International, 2016, 117(1): 179-191.

DOI：10.1111/bju.13180

• human detrusor smooth muscle
• permeabilization
• alpha-toxin
• cAMP
• calcium sensitization
• rho kinase

Objectives
To clarify the effect of cAMP on the Ca2+-sensitized smooth muscle contraction in human detrusor, as well as the role of novel exchange protein directly activated by cAMP (Epac) in cAMP-mediated relaxation.
Materials and Methods
All experimental protocols to record isometric tension force were performed using alpha-toxin-permeabilized human detrusor smooth muscle strips. The mechanisms of cAMP-mediated suppression of Ca2+ sensitization activated by 10 mu M carbachol (CCh) and 100 mu M GTP were studied using a selective rho kinase (ROK) inhibitor, Y-27632, and a selective protein kinase C (PKC) inhibitor, GF-109203X. The relaxation mechanisms were further probed using a selective protein kinase A (PKA) activator, 6-Bnz-cAMP and a selective Epac activator, 8-pCPT-20-O-Me-cAMP.
Results
We observed that CCh-induced Ca2+ sensitization was inhibited by cAMP in a concentration-dependent manner. GF-109203X (10 mu M) but not Y-27632 (10 mu M) significantly enhanced the relaxation effect induced by cAMP (100 mu M). 6-Bnz-cAMP (100 mu M) predominantly decreased the tension force in comparison with 8-pCPT-2'-O-Me-cAMP (100 mu M).
Conclusions
We showed that cAMP predominantly inhibited the ROK pathway but not the PKC pathway. The PKA-dependent pathway is dominant, while Epac plays a minor role in human detrusor smooth muscle Ca2+ sensitization.

• 出版日期2016-1