2004 Fiscal Year Final Research Report Summary
Ca^<2+> sensitization of human and rabbit urinary bladder smooth muscle
| Project/Area Number |
15591694
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Urology
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| Research Institution | KYUSHU UNIVERSITY |
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Principal Investigator |
SEKI Narihito KYUSHU UNIVERSITY, UROLOGY, ASSOCIATED PROFESSOR, 大学病院, 講師 (90294941)
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| Co-Investigator(Kenkyū-buntansha) |
NISHIMURA Junji KYUSHU UNIVERSITY, MOLECULAR CARDIOLOGY, ASSISTANT PROFESSOR, 大学院・医学研究院, 助教授 (90237727)
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| Project Period (FY) |
2003 – 2004
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| Keywords | Intracellular Ca concentration / Human detrusor smooth muscle / Ca sensitization / Rho kinase / Protein kinase C / Carbachol / Human prostate |
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| Research Abstract |
The role of Ca^<2+> sensitization in contraction of human urinary bladder smooth muscle(UBSM) was investigated.
Simultaneous measurements of intracellular Ca^<2+> concentration ([Ca^<2+>]_i) and tension in fura-2 loaded intact strips and receptor-coupled strips permeabilized with crtoxin were applied. The expressions of proteins were confirmed by western blot analysis.
In intact fura-2 loaded strips, 1 μM carbachol (CCh) induced a greater contraction and a lower [Ca^<2+>]_i elevation than that induced by 60 mM K^+ depolarization. In α-toxin permeabilized strips, 1 μM CCh induced contraction at constant [Ca^<2+>]_i and produced a leftward shift in [Ca^<2+>]_i-tension relationship. RhoA, Rho-associated kinase (ROCK) I, ROCK II and CPI-17 proteins were expressed in human UBSM. In intact fura-2 loaded strips, application of 3 μM Y-27632(a ROCK inhibitor) or 3 μM GF109203X (a protein kinase C(PKC) inhibitor) during the sustained phase of contraction induced by 1 μM CCh induced a relaxation without changing [Ca^<2+>]_i. In α-toxin permeabilized strips, application of 3 μM Y-27632 or 3 μM GF109203X during the sustained contraction induced by 0.3 μM Ca^<2+> plus 10 μM GTP and 1 μM CCh induced a relaxation at constant [Ca^<2+>]_i.
These results indicate that in human UBSM, CCh induces a contraction not only by increasing [Ca^<2+>]_i but also by increasing the Ca^<2+> sensitivity of the contractile apparatus in a ROCK and PKC dependent manner. Antagonism of Ca^<2+> sensitization pathways may represent an alternative target in the treatment of overactive bladder.
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